'Born-again' star offers rare chance to watch stellar evolution in real time

This image captures the ancient planetary nebula ejected by Sakurai's Object when the star died for the first time. The star itself is not visible, as it was captured before it began brightening again. Credit :ESO, 2004

Licence type: Attribution (CC BY 4.0)

Astronomers have confirmed that one of the fastest-changing stars ever observed has entered a new stage of its evolution, offering a rare opportunity to watch a star's life unfold on human timescales.

Using the European Southern Observatory's Very Large Telescope (VLT) in Chile, researchers, involving scientists from The University of Manchester and The Valongo Observatory, studied Sakurai's Object, a rare 'born-again' star that unexpectedly burst back to life in 1996 after reaching the final stages of its evolution.

Their findings, published today in Monthly Notices of the Royal Astronomical Society, show that the star has entered a new phase of its evolution, developing the powerful stellar wind characteristic of Wolf-Rayet stars.

The research provides new insight into the final stages of stellar evolution and helps astronomers test theories that would otherwise take thousands or millions of years to verify.

Professor Albert Zijlstra, from Jodrell Bank Centre for Astrophysics at The University of Manchester, said: "Most stars evolve so slowly that major changes take place over timescales far longer than a human lifetime. As a result, we usually have to piece together snapshots of stellar evolution by comparing different stars at different stages of their lives.

"Sakurai's Object offers something far rarer. It is one of the very few stars known to have changed dramatically within just a few decades, giving us the opportunity to watch stellar evolution unfold in real time. Thirty years ago, the star had a temperature similar to our Sun. Now, it is five times as hot, the fastest rate of increase ever seen.

'Born-again' star animation

"With our observations, we can test theories of how stars evolve and gain new insights into one of the shortest and least understood phases in the life of a dying star."

The scientists believe the star was similar to our Sun, but had already ended nuclear burning and begun its journey towards becoming a white dwarf - the hot, dense core left behind after an ordinary star dies. It underwent a rare event known as a "very late thermal pulse", when a layer of helium deep inside the dead star suddenly reignites. The event caused the star to rapidly expand, cool and eject large amounts of material into space, temporarily returning to an earlier stage of its life, leading astronomers to describe it as a "born-again" star.

Only two stars have ever been directly observed undergoing this type of dramatic rebirth: Sakurai's Object and V605 Aquilae. Following its outburst, Sakurai's Object became hidden behind thick clouds of gas and dust released during the eruption, making it difficult to study directly.

To investigate its current state, the team analysed light collected by the VLT and compared it with sophisticated computer models that simulate the atmospheres and powerful winds of Wolf-Rayet stars.

The observations revealed distinctive signatures of carbon and helium, allowing the researchers to find its temperature, chemical composition and the characteristics of its stellar wind.

Their analysis suggests the star's surface temperature is currently between around 27,000 and 36,000 degrees Kelvin, showing that it is reheating following its dramatic eruption nearly three decades ago.

Professor Zijlstra added: "One of the key questions is how quickly Sakurai's Object should recover after its dramatic eruption.

"Our measurements show that the star is reheating more gradually than some earlier models predicted. That gives us an important way of testing which theories best describe what happens when a dying star briefly springs back to life.

"As we continue to monitor the star over the coming years, we expect to learn much more about this remarkable phase of stellar evolution."

The findings also suggest that Sakurai's Object is at an earlier stage of its evolution than V605 Aquilae, which experienced a similar event around 80 years ago.

The team will continue observing Sakurai's Object as it continues reheating and resumes its journey towards becoming a white dwarf, learning more about one of the most rapid and unusual phases of stellar evolution ever observed.

Source: Royal Astronomical Society (RAS)/Research Highlights

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Media contacts:

Sam Tonkin
Royal Astronomical Society
Mob: +44 (0)7802 877 700
press@ras.ac.uk

Jessica Marsh
The University of Manchester
Mob: +44 (0)7780 281312
jessica.marsh@manchester.ac.uk

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Science contacts:

Professor Albert Zijlstra
The University of Manchester
albert.zijlstra@manchester.ac.uk

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Images & captions

Sakurai's Object

Caption: This image captures the ancient planetary nebula ejected by Sakurai's Object when the star died for the first time. The star itself is not visible, as it was captured before it began brightening again.

Credit: ESO, 2004

‘Born-again’ star still

Caption: A still image of the animation showing Sakurai's Object as it was captured three years ago.

Credit: Peter van Hoof

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Further information

The paper 'The emergence of a [WC] star in Sakurai's object' by Marcolini et al. has been published in Monthly Notices of the Royal Astronomical Society. DOI: 10.1093/mnras/stag1533.

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Notes for editors

About the Royal Astronomical Society

The Royal Astronomical Society (RAS), founded in 1820, encourages and promotes the study of astronomy, solar-system science, geophysics and closely related branches of science.

The RAS organises scientific meetings, publishes international research journals, recognises outstanding achievements by the award of medals and prizes, maintains an extensive library, supports education through grants and outreach activities and represents UK astronomy nationally and internationally. Its more than 4,000 members (Fellows), a third based overseas, include scientific researchers in universities, observatories and laboratories as well as historians of astronomy and others.

The RAS accepts papers for its journals based on the principle of successful peer review, following which experts on the Editorial Boards accept the papers for publication. The Society issues press releases based on a similar principle, but the organisations and scientists concerned have overall responsibility for their content.

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Submitted by Sam Tonkin on Wed, 16/09/2026 - 10:00

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A Quintillion-to-One: Giant Stars, Tiny Dust

Artist’s impression of WR 112, a binary system containing a massive, evolved Wolf-Rayet star and an OB-type companion. As their stellar winds collide, dust forms and spirals outward, consisting mostly of extremely tiny, nanometer-sized grains along with a secondary population about 100 times larger. Credit: NSF/AUI/NSF NRAO/M. Weiss. Hi-Res File

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ALMA and JWST reveal nanometer-scale carbon dust grains emanating from a massive binary star system

Telescope (JWST) have discovered that some of the most massive stars in our galaxy are emitting unbelievably tiny grains of carbon dust—dust that one day could form future stars and planets. Both powerful telescopes were required for this research, to reveal all of the dust being produced by these stars.

This new research focused on WR 112, a binary star system that contains a very rare, massive, intensely hot, and dying Wolf–Rayet star orbiting another star companion. Together, these stars blast out powerful stellar winds that collide and create dense, cooling regions where dust forms, before this dust is scattered into interstellar space by intense starlight.

While previous mid-infrared images from JWST revealed bright spiral arcs of dust in WR 112, researchers were surprised when they saw no dust at all in ALMA’s sensitive millimeter observations. Only warm, tiny dust grains could hide from ALMA’s view, one of the most powerful millimeter telescopes on Earth. Combined data from JWST and ALMA suggested that the dust grains in the extended spiral structures are largely smaller than one micrometer, and most of them should be only a few nanometers (or billionths of a meter) across.

“It’s amazing to know that some of the most massive stars in the Universe produce some of the tiniest dust particles before they die. The difference in size between the star and the dust it produces is about a quintillion to one,” shared Donglin Wu, an undergraduate at Yale University and the lead author of this new research.

The team also found evidence that the dust is not evenly made up of a range of sizes, but instead comes in two distinct sizes: a larger group of nanometer-sized grains, and a smaller group of grains about 0.1 micrometer across. This discovery reconciled decades of conflicting measurements of similar binary systems: some revealed only very tiny grains, while others only saw larger ones. Now, it is understood that this type of binary system can have both. The team explored several physical processes that can, in principle, break up or evaporate dust grains near the harsh radiation field of the stars, finding that these processes have a tendency to destroy grains that were in between these sizes under certain conditions.

Because WR 112 is one of the most prolific dust producers of its kind—producing as much as three Moons’ worth of dust every year—the new grain-size measurements have big implications for how much carbon dust massive binaries can contribute to the broader galaxy. By revealing that some of the Universe’s biggest stars are factories for some of its smallest solid particles, this study provides an important missing piece in the life cycle of cosmic dust.

Source: National Radio Astronomy Observatory (NRAO)/News

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Press Contacts:

Jill Malusky
Sr. Public Information Group Manager and Public Information Officer

Email | Phone

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About NRAO

The National Radio Astronomy Observatory (NRAO) is a facility of the U.S. National Science Foundation, operated under cooperative agreement by Associated Universities, Inc.

About ALMA

The Atacama Large Millimeter/submillimeter Array (ALMA), an international astronomy facility, is a partnership of the European Southern Observatory (ESO), the U.S. National Science Foundation (NSF) and the National Institutes of Natural Sciences (NINS) of Japan in cooperation with the Republic of Chile. ALMA is funded by ESO on behalf of its Member States, by NSF in cooperation with the National Research Council of Canada (NRC) and the National Science and Technology Council (NSTC) in Taiwan and by NINS in cooperation with the Academia Sinica (AS) in Taiwan and the Korea Astronomy and Space Science Institute (KASI).

ALMA construction and operations are led by ESO on behalf of its Member States; by the National Radio Astronomy Observatory (NRAO), managed by Associated Universities, Inc. (AUI), on behalf of North America; and by the National Astronomical Observatory of Japan (NAOJ) on behalf of East Asia. The Joint ALMA Observatory (JAO) provides the unified leadership and management of the construction, commissioning and operation of ALMA.

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Stars That Die Off the Beaten Path

This artist's impression of the M33 galaxy, with data inset from ALMA and the NSF VLA, shows the supernova remnant astronomers believe to be caused by a supernova explosion some 10,000 years ago. This new reserach suggests that the Wolf-Rayet may explode as a supernova in the next 0.5-1 million years. Credit: NSF/AUI/NRAO/B.Saxton. Hi-Res File

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By tracking thousands of massive, dying stars in nearby galaxy M33, astronomers have drawn the first large‑scale map of potential supernova blast sites

Astronomers have created a detailed forecast of where they expect to observe future stellar explosions in a nearby galaxy, opening a new window into how exploding stars shape the cosmos. Focusing on M33, a spiral galaxy about 2.7 million light‑years away, this research combined new maps of cold atomic hydrogen gas from the U.S. National Science Foundation Very Large Array (NSF VLA) with millimeter‑wave observations of molecular gas from the Atacama Large Millimeter/submillimeter Array (ALMA).

Massive stars end their lives in titanic supernova explosions. These blasts influence how galaxies grow by stirring gas, driving winds, and seeding space with heavy elements. How much impact a single explosion has depends on where it happens: a blast inside a dense cloud of gas behaves very differently than one in a relatively empty region. Until now, astronomers have had few opportunities to observe this problem, because supernovae are rare, and typically too far away to study in detail.

This new study offers a solution to this problem, by shifting telescopes to observe future supernova sites instead. The team mapped the gas, at various wavelengths, around thousands of evolved, massive stars in M33. These are stars that are expected to explode as core‑collapse supernovae within a few million years. On top of these gas maps, the team overlaid catalogs of three types of objects: red supergiants, Wolf–Rayet stars, and supernova remnants. Red supergiants are bloated, dying massive stars that are known progenitors of most Type II supernovae, while Wolf–Rayet stars are hotter, more massive, and shorter‑lived, and are linked to stripped‑envelope explosions and some gamma‑ray bursts. Supernova remnants mark locations where massive stars have already exploded in the past 10,000–100,000 years.

By shifting their focus, these astronomers have assembled the first large, quantitative census of the environments in which massive stars will eventually end their existence. “What we found was surprising,” shares Sumit Sarbadhicary, of Johns Hopkins University, and lead author of this research. “A large fraction of these future supernovae are expected to explode outside of the dense molecular clouds.” Only about 30–40 percent of red supergiants and a similar fraction of supernova remnants sit in regions where molecular hydrogen is detected, while the remaining majority lie in lower‑density, primarily atomic gas. Even among the youngest, most massive Wolf–Rayet stars, roughly 45 percent show no detectable molecular gas at their exact locations.

At the same time, almost all of these stars do reside somewhere within the broader disk of cold gas: more than 90% are found in regions with detectable atomic hydrogen. This means that many supernovae will not explode inside of dense, star‑forming clouds, but in the surrounding, more diffuse intercloud medium. In those environments, supernova blast waves can travel farther before cooling, changing how and where they inject energy and momentum into the galaxy.

When the team sorted stars by their estimated birth masses, a clear trend emerged: the higher the mass of the star, the denser its surrounding gas. More massive red supergiants, and especially Wolf–Rayet stars, are statistically more likely to be found close to peaks in the molecular gas distribution than their lower‑mass counterparts. This is consistent with the idea that the most massive, shortest‑lived stars explode before they have time to drift far from their birth clouds or before those clouds have fully dispersed.

Still, the study finds that even these massive stars often inhabit complex surroundings. In one detailed zoom using ultra‑high‑resolution ALMA data, a Wolf–Rayet star that appears to sit in a dense cloud at coarse resolution is actually embedded in a small, roughly 10‑light‑year‑wide cavity carved out of the molecular gas. That cavity was likely created by intense radiation, stellar winds, or a previous supernova, and it will strongly influence how the Wolf–Rayet star’s own explosion interacts with nearby gas.

The data used in this research is part of the Local Group L-Band Survey, a radio survey at 1-2 GHz of Local Group galaxies, including Triangulum (referenced here), Andromeda, and four other dwarf galaxies (NGC 6822, WLM, IC 1613 and IC10). Team members essential to gathering and assembling this data include Eric Koch of the NSF NRAO, Adam Leroy of Ohio State University, and Erik Rosolowsky of the University of Alberta, Canada. The maps created in this survey will become the most sensitive maps of atomic hydrogen in these galaxies, with preliminary versions being used in Sarbadhicary’s current paper.

Because large computer simulations of galaxies must approximate where supernovae occur, this new census offers a way to check these projections against reality. Galaxy simulations (including those used in research projects like FIRE, Illustris, TIGRESS, SILCC) are the only way in which astronomers can study millions, and billions, of years of galaxy evolution. However, the simulations must to approximate the physics at the scales of individual stars and molecular clouds. Observations such as these will be vital, and much needed, for these simulations to benchmark the sub-scale (or subgrid) physics from stars, in order to accurately capture how these stars disperse gas, drive winds and regulate the overall star-formation in galaxies. The Local Group L-Band Survey will capture the highest resolution maps of gas around stars to understand this longstanding mystery of how efficiently stars form and disperse the cold gas reservoir in galaxies.

This comparison flagged how simulations treat radiation, winds, clustering, and runaway stars, suggesting they may need refinement to better match observed environments. The team argues that similar comparisons, extended to more galaxies and higher‑resolution gas maps, can help narrow down which feedback models most faithfully reproduce how real supernovae sculpt the interstellar medium.

“As this research continues, we’re aiming to expand this collection by sampling another 80 star-forming galaxies,” adds Sarbadhicary. “We also have upcoming maps of M33 from ALMA, led by team members Eric Koch and Erik Rosolowsky, that will be significantly sharper than the present study, revealing even more detailed, complex environments like the Wolf-Rayet star mentioned earlier.” By treating evolved massive stars and recent remnants as signposts of present and future explosion sites, astronomers continue to grow their understanding of how those explosions will continue to shape galaxies like M33, and our own Milky Way. Sarbadhicary and the nearby galaxy research community are directing their efforts to produce the sharpest maps of interstellar gas with instruments like NSF VLA, ALMA, and NASA’s JWST, and in future with the NSF NRAO’s proposed Next Generation Very Large Array. Stars form from gas, but stars also destroy. These maps are crucial to understand how this curious contradiction, yet vital process, drives the evolution of galaxies.

Source: National Radio Astronomy Observatory (NRAO)/News

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Links:

Scientific Paper
Local Group L-Band Survey

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About ALMA

The Atacama Large Millimeter/submillimeter Array (ALMA), an international astronomy facility, is a partnership of the European Southern Observatory (ESO), the U.S. National Science Foundation (NSF) and the National Institutes of Natural Sciences (NINS) of Japan in cooperation with the Republic of Chile. ALMA is funded by ESO on behalf of its Member States, by NSF in cooperation with the National Research Council of Canada (NRC) and the National Science and Technology Council (NSTC) in Taiwan and by NINS in cooperation with the Academia Sinica (AS) in Taiwan and the Korea Astronomy and Space Science Institute (KASI).

ALMA construction and operations are led by ESO on behalf of its Member States; by the National Radio Astronomy Observatory (NRAO), managed by Associated Universities, Inc. (AUI), on behalf of North America; and by the National Astronomical Observatory of Japan (NAOJ) on behalf of East Asia. The Joint ALMA Observatory (JAO) provides the unified leadership and management of the construction, commissioning and operation of ALMA.

About NRAO

The National Radio Astronomy Observatory (NRAO) is a facility of the U.S. National Science Foundation, operated under cooperative agreement by Associated Universities, Inc.

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Bright Blue Cosmic Outbursts Likely Caused by Large Black Holes Shredding Massive Companions

PR Image noirlab2533a
Most luminous fast blue optical transient

PR Image noirlab2533b
Most luminous fast blue optical transient (collage)

PR Image noirlab2533c
Most luminous fast blue optical transient infographic

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Quickly-fading luminous blue outbursts were once thought to be unusual supernovae, but a new outburst, the brightest yet, suggests otherwise

In 2024, astronomers discovered the brightest Luminous Fast Blue Optical Transient (LFBOT) ever observed. LFBOTs are extremely bright flashes of blue light that shine for brief periods before fading away. New analysis of this record-breaking burst, which includes observations from the International Gemini Observatory, funded in part by the U.S. National Science Foundation, challenges all prior understanding of these rare explosive events.

Among the more puzzling cosmic phenomena discovered over the past few decades are brief and very bright flashes of blue and ultraviolet light that gradually fade away, leaving behind faint X-ray and radio emissions. This curious class of objects is known as luminous fast blue optical transients (LFBOTs), and with slightly more than a dozen discovered so far, astronomers have debated whether they are produced by an unusual type of supernova or by interstellar gas falling into a black hole.

Analysis of the brightest LFBOT to-date, named AT 2024wpp and discovered last year, shows that they’re neither. Instead, a team led by researchers from the University of California, Berkeley, concluded that they are caused by an extreme tidal disruption, where a black hole of up to 100 times the mass of our Sun completely shreds its massive star companion within days.

This discovery resolves a decade-long conundrum but also illustrates the many varieties of stellar calamities that astronomers encounter, each with its characteristic spectrum of light that evolves over time. Figuring out the processes that produce these unique light signatures tests current knowledge of the physics of black holes and helps astronomers understand the evolution of stars in our Universe.

The team’s analysis of AT 2024wpp is presented in two papers recently accepted by The Astrophysical Journal Letters. The studies utilize data from a large collection of telescopes that measured the various wavelengths of light emitted by the LFBOT [2]. Crucial near-infared data was collected with the Flamingos-2 instrument on the Gemini South telescope in Chile, one half of the International Gemini Observatory, funded in part by the U.S. National Science Foundation and operated by NSF NOIRLab.

“The ongoing discovery of luminous fast blue optical transients shows that Gemini South and other ground-based astronomical facilities are primed to characterize these mysterious objects,” says Martin Still, NSF program director for the International Gemini Observatory. “We expect the NSF–DOE Vera C. Rubin Observatory will spot large numbers of these transient objects, giving Gemini and other telescopes unprecedented opportunities for detailed follow-up observations.”

LFBOTs got their name because they are bright — they’re visible over distances of hundreds of millions to billions of light years — and last for only a few days. They produce high-energy light ranging from the blue end of the optical spectrum through ultraviolet and X-ray. The first was seen in 2014, but the first with sufficient data to analyze was recorded in 2018 and, per the standard naming convention, was called AT 2018cow. The name led researchers to refer to it as the Cow, and subsequent LFBOTs have been called, tongue in cheek, the Koala (ZTF18abvkwla), the Tasmanian devil (AT 2022tsd) and the Finch (AT 2023fhn). Perhaps AT 2024wpp will be known as the Wasp.

The realization that AT 2024wpp could not have resulted from a supernova came after the researchers calculated the energy it emitted. It turned out to be 100 times greater than what would be produced in a normal supernova. The radiated energy would require the conversion of about 10% of the rest-mass of the Sun into energy over a very short time scale of weeks.

Specifically, the Gemini South observations revealed an excess of near-infrared light being emitted from the source. This is only the second time astronomers have observed such a phenomenon (the other case being AT 2018cow), which is clearly not present in ordinary stellar explosions. These observations establish the near-infrared excess as a hallmark feature of FBOTs, though no model can explain this occurrence.

“The sheer amount of radiated energy from these bursts is so large that you can't power them with a core collapse stellar explosion — or any other type of normal stellar explosion,” says Natalie LeBaron, UC Berkeley graduate student and first author on the paper presenting the Gemini data [1]. “The main message from AT 2024wpp is that the model that we started off with is wrong. It’s definitely not just an exploding star.”

The researchers hypothesize that the intense, high-energy light emitted during this extreme tidal disruption was a consequence of the long parasitic history of the black hole binary system. As they reconstruct this history, the black hole had been sucking material from its companion for a long time, completely enshrouding itself in a halo of material too far from the black hole for it to swallow.

Then, when the companion star finally got too close and was torn apart, the new material became entrained into the rotating accretion disk and slammed against the existing material, generating X-ray, ultraviolet, and blue light. Much of the gas from the companion also ended up swirling toward the poles of the black hole, where it was ejected as a jet of material. The team calculated that the jets were traveling at about 40% of the speed of light and generated radio waves when they encountered surrounding gas.

Like most LFBOTs, AT 2024wpp is located in a galaxy with active star formation, so large stars like these are expected. AT 2024wpp is 1.1 billion light years away and between 5 and 10 times more luminous than AT 2018cow.

The estimated mass of the companion star that was shredded was more than 10 times the mass of the Sun. It may have been what’s known as a Wolf-Rayet star, which is a very hot and evolved star that has already used up much of its hydrogen. This would explain the weak hydrogen emission from AT 2024wpp.

Source: NSF’s National Optical-Infrared Astronomy Research Laboratory (NOIRLab)/News

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Notes

[1] Natalie LeBaron et al. presents an analysis of the optical, ultraviolet and near infrared data. A companion paper by Nayana A.J. et al. presents an analysis of the X-ray and radio data.

[2] In addition to Gemini South, this study includes observations made with NASA’s Chandra X-ray Observatory, Swift-XRT, the Nuclear Spectroscopic Telescope Array (NuSTAR), the Atacama Large Millimeter/submillimeter Array (ALMA), the Australia Telescope Compact Array (ATCA), the Ultra-Violet/Optical Telescope (UVOT) on NASA’s Neil Gehrels Swift Observatory, the W.M. Keck Observatory, and Lick Observatory.

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More information

This research was presented in a paper titled “The Most Luminous Known Fast Blue Optical Transient AT 2024wpp: Unprecedented Evolution and Properties in the Ultraviolet to the Near-Infrared,” uploaded to arXiv and accepted for publication in The Astrophysical Journal Letters.

The team is composed of N. LeBaron (UC Berkeley, USA), R. Margutti (UC Berkeley, USA), R. Chornock (UC Berkeley, USA), N. A. J. (UC Berkeley, USA), O. Aspegren (UC Berkeley, USA), W. Lu (UC Berkeley, USA), B. D. Metzger (Columbia University/Flatiron Institute, USA), D. Kasen (UC Berkeley/Lawrence Berkeley National Laboratory, USA), T. G. Brink (UC Berkeley, USA), S. Campana (INAF, Italy), P. D’Avanzo (INAF, Italy), J. T. Faber (California Institute of Technology, USA), M. Ferro (University of Insubria/INAF, Italy), A. V. Filippenko (UC Berkeley, USA), R. J. Foley (UC Santa Cruz, USA), X. Guo (UC Berkeley, USA), E. Hammerstein (UC Berkeley, USA), S. W. Jha (Rutgers University, USA), C. D. Kilpatrick (Northwestern University, USA), G. Migliori (INAF, Italy), D. Milisavljevic (Purdue University, USA), K. C. Patra (UC Santa Cruz, USA), H. Sears (Rutgers University, USA), J. J. Swift (The Thacher School, USA) , S. Tinyanont (NARIT, Thailand), V. Ravi (California Institute of Technology, USA), Y. Yao (UC Berkeley, USA), K. D. Alexander (Steward Observatory, USA), P. Arunachalam (UC Santa Cruz, USA), E. Berger (Center for Astrophysics | Harvard & Smithsonian, USA), J. S. Bright (University of Oxford, UK), C. Cynamon (Supra Solem Observatory, USA), K. W. Davis (UC Santa Cruz, USA), B. Garretson (Purdue University, USA), P. Guhathakurta (UC Santa Cruz, USA), W. V. Jacobson-Galán (California Institute of Technology, USA), D. O. Jones (Gemini Observatory/NSF NOIRLab, USA), R. Kaur (UC Santa Cruz, USA), S. Kimura (Willamette University, USA), T. Laskar (University of Utah, USA/Radboud University, The Netherlands), Morgan Nuñez (San Francisco State University, USA), M. Schwab (Rutgers University, USA), M. D. Soraisam (Gemini Observatory/NSF NOIRLab, USA), N. Suzuki (Lawrence Berkeley National Laboratory/Florida State University, USA), K. Taggart (UC Santa Cruz, USA), E. Wiston (UC Berkeley, USA), Y. Yang (Tsinghua University, China), and W. Zheng (UC Berkeley, USA).

NSF NOIRLab, the U.S. National Science Foundation center for ground-based optical-infrared astronomy, operates the International Gemini Observatory (a facility of NSF, NRC–Canada, ANID–Chile, MCTIC–Brazil, MINCyT–Argentina, and KASI–Republic of Korea), NSF Kitt Peak National Observatory (KPNO), NSF Cerro Tololo Inter-American Observatory (CTIO), the Community Science and Data Center (CSDC), and NSF–DOE Vera C. Rubin Observatory (in cooperation with DOE’s SLAC National Accelerator Laboratory). It is managed by the Association of Universities for Research in Astronomy (AURA) under a cooperative agreement with NSF and is headquartered in Tucson, Arizona.

The scientific community is honored to have the opportunity to conduct astronomical research on I’oligam Du’ag (Kitt Peak) in Arizona, on Maunakea in Hawai‘i, and on Cerro Tololo and Cerro Pachón in Chile. We recognize and acknowledge the very significant cultural role and reverence of I’oligam Du’ag to the Tohono O’odham Nation, and Maunakea to the Kanaka Maoli (Native Hawaiians) community.

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Links

• Read the paper: The Most Luminous Known Fast Blue Optical Transient AT 2024wpp: Unprecedented Evolution and Properties in the Ultraviolet to the Near-Infrared


• UC Berkeley press release


• Read the companion paper: The Most Luminous Known Fast Blue Optical Transient AT 2024wpp: Unprecedented Evolution and Properties in the X-rays and Radio


• Chandra X-ray Observatory announcement


• Photos of the Gemini South telescope


• Videos of the Gemini South telescope


• Check out other NOIRLab Science Releases

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Contacts:

Natalie LeBaron
Graduate student
UC Berkeley
Email: nlebaron@berkeley.edu

Josie Fenske
Public Information Officer
NSF NOIRLab
Email: josie.fenske@noirlab.edu

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Massive stars make their mark

Markarian 178

A pale blue dwarf galaxy seen on the black backdrop of space with some faraway galaxies. The galaxy itself resembles a fuzzy cloud of tightly-packed stars, with a broad halo of stars dispersed around it. Several small, glowing patches of gas are spread across the galaxy’s core, where very hot stars are concentrated. Credit: ESA/Hubble & NASA, F. Annibali, S. Hong

This glittering blue galaxy and subject of today’s ESA/Hubble Picture of the Week is a blue compact dwarf galaxy called Markarian 178 (Mrk 178). This galaxy, which is substantially smaller than our own Milky Way, lies 13 million light-years away in the constellation Ursa Major (The Great Bear).

Mrk 178 is one of more than 1500 Markarian galaxies. These galaxies get their name from the Armenian astrophysicist Benjamin Markarian, who compiled a list of galaxies that were surprisingly bright in ultraviolet light.

While the bulk of the galaxy is blue owing to an abundance of young, hot stars with little dust shrouding them, Mrk 178 gets a red hue from a collection of massive stars, which are especially concentrated in the brightest, reddish region near the galaxy’s edge. This azure cloud is home to a large number of rare objects called Wolf–Rayet stars. Wolf–Rayet stars are massive stars that are casting off their atmospheres through powerful winds. Because Mrk 178 contains so many Wolf–Rayet stars, the bright emission lines from these stars’ hot stellar winds are etched upon the galaxy’s spectrum. Particularly ionised hydrogen and oxygen appear as a red colour to Mrk 178 in this photo, observed using some of Hubble’s specialised light filters.

Massive stars enter the Wolf–Rayet phase just before they collapse into black holes or neutron stars. Because Wolf–Rayet stars last for only a few million years, researchers know that something must have triggered a recent burst of star formation in Mrk 178. At first glance, it’s not clear what could be the cause — Mrk 178 doesn’t seem to have any close galactic neighbours that could have stirred up its gas to form new stars. Astronomers believe that it was triggered by the interaction with a smaller satellite, as revealed by the presence of low surface brightness tidal features detected around Mrk178 in deep imaging acquired with the Large Binocular Telescope. Future high resolution Hubble data will be crucial to study the detailed star formation history of Mrk 178.

Source: ESA/Hubble/potw

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Webb First to Show 4 Dust Shells 'Spiraling' Apep, Limits Long Orbit View All Press Releases

Wolf-Rayet Apep (MIRI Image)

Webb’s mid-infrared image shows four coiled shells of dust around a pair of Wolf-Rayet stars known as Apep for the first time. Previous observations by other telescopes showed only one. Webb’s data also confirmed that there are three stars gravitationally bound to one another.nCredits: Image: NASA, ESA, CSA, STScI; Science: Yinuo Han (Caltech), Ryan White (Macquarie University); Image Processing: Alyssa Pagan (STScI)

Wolf-Rayet Apep (MIRI Compass Image)
This image was created with Webb data from proposal: 5842 (Y. Han). Image processing: Alyssa Pagan (STScI).

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NASA’s James Webb Space Telescope has delivered a first of its kind: a crisp mid-infrared image of a system of four serpentine spirals of dust, one expanding beyond the next in precisely the same pattern. (The fourth is almost transparent, at the edges of Webb’s image.) Observations taken prior to Webb only detected one shell, and while the existence of outer shells was hypothesized, searches using ground-based telescopes were unable to uncover any. These shells were emitted over the last 700 years by two aging Wolf-Rayet stars in a system known as Apep, a nod to the Egyptian god of chaos.

Webb’s image combined with several years of data from the European Southern Observatory’s Very Large Telescope (VLT) in Chile narrowed down how often the pair swing by one another: once every 190 years. Over each incredibly long orbit, they pass closely for 25 years and form dust.

Webb also confirmed that there are three stars gravitationally bound to one another in this system. The dust ejected by the two Wolf-Rayet stars is “slashed” by a third star, a massive supergiant, which carves holes into each expanding cloud of dust from its wider orbit. (All three stars are shown as a single bright point of light in Webb’s image.)

“Looking at Webb’s new observations was like walking into a dark room and switching on the light — everything came into view,” said Yinuo Han, the lead author of a new paper in The Astrophysical Journal and postdoctoral researcher at Caltech in Pasadena, California. “There is dust everywhere in Webb’s image, and the telescope shows that most of it was cast off in repetitive, predictable structures.” Han’s paper coincides with the publication of Ryan White’s paper in The Astrophysical Journal, a PhD student at Macquarie University in Sydney, Australia.

Han, White, and their co-authors refined the Wolf-Rayet stars’ orbit by combining precise measurements of the ring location from Webb’s image with the speed of the shells’ expansion from observations taken by the VLT over eight years.

“This is a one-of-a-kind system with an incredibly rare orbital period,” White said. “The next longest orbit for a dusty Wolf-Rayet binary is about 30 years. Most have orbits between two and 10 years.”

When the two Wolf-Rayet stars approach and pass one another, their strong stellar winds collide and mix, forming and casting out heaps of carbon-rich dust for a quarter century at a time. In similar systems, dust is shot out over mere months, like the shells in Wolf-Rayet 140.
High-speed ‘skirmish’

The dust-producing Wolf-Rayet stars in Apep aren’t exactly on a tranquil cruise. They are whipping through space and sending out dust at 1,200 to 2,000 miles per second (2,000 to 3,000 kilometers per second).

That dust is also very dense. The specific makeup of the dust is another reason why Webb was able to observe so much more: It largely consists of amorphous carbon. “Carbon dust grains retain a higher temperature even as they coast far away from the star,” Han said. While the exceptionally tiny dust grains are considered warm in space, the light they emit is also extremely faint, which is why it can only be detected from space by Webb’s MIRI (Mid-Infrared Instrument).

Slicing dust

To find the holes the third star has cut like a knife through the dust, look for the central point of light and trace a V shape from about 10 o’clock to 2 o’clock. “The cavity is more or less in the same place in each shell and looks like a funnel,” White said.

“I was shocked when I saw the updated calculations play out in our simulations,” he said. “Webb gave us the ‘smoking gun’ to prove the third star is gravitationally bound to this system.” Researchers have known about the third star since the VLT observed the brightest innermost shell and the stars in 2018, but Webb’s observations led to an updated geometric model, clinching the connection. (See the system in 3D by watching the visualization below.)

Video A: Wolf-Rayet Apep Visualization

This scientific visualization models what three of the four dust shells sent out by two Wolf-Rayet stars in the Apep system look like in 3D based on mid-infrared observations from NASA’s James Webb Space Telescope. Apep is made up of two Wolf-Rayet binary stars . Image: NASA, ESA, CSA, STScI; Simulation: Yinuo Han (Caltech), Ryan White (Macquarie University); Visualization: Christian Nieves (STScI); Image Processing: Alyssa Pagan (STScI)

“We solved several mysteries with Webb,” Han said. “The remaining mystery is the precise distance to the stars from Earth, which will require future observations.”

Future of Apep

The two Wolf-Rayet stars were initially more massive than their supergiant companion, but have shed most of their mass. It’s likely that both Wolf-Rayet stars are between 10 and 20 times the mass of the Sun, and that the supergiant is 40 or 50 times as massive compared to the Sun. Eventually, the Wolf-Rayet stars will explode as supernovae, quickly sending their contents into space. Either may also emit a gamma-ray burst, one of the most powerful events in the universe, before possibly becoming a black hole.

Wolf-Rayet stars are incredibly rare in the universe. Only a thousand are estimated to exist in our Milky Way galaxy, which contains hundreds of billions of stars overall. Of the few hundred Wolf-Rayet binaries that have been observed to date, Apep is the only example that contains two Wolf-Rayet stars of these types in our galaxy — most only have one.

The James Webb Space Telescope is the world’s premier space science observatory. Webb is solving mysteries in our solar system, looking beyond to distant worlds around other stars, and probing the mysterious structures and origins of our universe and our place in it. Webb is an international program led by NASA with its partners, ESA (European Space Agency) and CSA (Canadian Space Agency).

Source: https://science.nasa.gov/mission/webb/

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Related Information

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Read more:Webb Reveals Shells of Dust Surrounding Brilliant Binary Star System

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Explore more: ViewSpace Variable stars: V838 Mon

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. SpacePlace for Kids

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Famed WR 104 “Pinwheel” Star Reveals Another Surprise (and Some Relief)

An artist’s concept of the famous Wolf-Rayet 104 “pinwheel star,” previously nicknamed the “Death Star.” New research conducted from Maunakea, Hawaiʻi using three Keck Observatory instruments reveals the orbit of the two stars are angled 30 or 40 degrees away from us, sparing Earth from a potential gamma-ray burst (GRB). Credit: W. M. Keck Observatory/Adam Makarenko

An artist’s animation of WR 104, first discovered at Keck Observatory in 1999. It consists of two stars orbiting each other; a Wolf-Rayet star that produces a powerful, carbon-rich wind (depicted in yellow), and an OB star that creates a wind mostly made of hydrogen (depicted in blue). When the winds collide, they whip up a hydrocarbon “dust” spiral. Credit: W. M. Keck Observatory/Adam Makarenko

An infrared image of WR 104 captured by Keck Observatory’s NIRC instrument in 1998
Credit: U.C. Berkeley Space Sciences Laboratory/W. M. Keck Observatory

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A new spin on decades of W. M. Keck Observatory research

Maunakea, Hawaiʻi – A recent study reveals the famous Wolf-Rayet 104 “pinwheel star” holds more mystery but is even less likely to be the potential ‘Death Star’ it was once thought to be.

Research by W. M. Keck Observatory Instrument Scientist and astronomer Grant Hill finally confirms what has been suspected for years: WR 104 has at its heart a pair of massive stars orbiting each other with a period of about 8 months and the collision between their powerful winds gives rise to its rotating pinwheel of dust that glows in the infrared, and spins with the same period.

The pinwheel structure of WR 104 was discovered at Keck Observatory in 1999 and the remarkable images of it turning in the sky astonished astronomers. One of the two stars that were suspected to orbit each other – a Wolf-Rayet star– is a massive, evolved star that produces a powerful wind highly enriched with carbon. The second star – a less evolved but even more massive OB star – has a strong wind that is still mostly hydrogen. Collisions between winds like these are thought to allow hydrocarbons to form, often referred to as “dust” by astronomers. When discovered, WR 104 also made headlines as a potential gamma-ray burst (GRB) that could be aimed right at us. Models of the pinwheel images indicated it was rotating in the plane of the sky as if we were looking directly down on someone spinning a streaming garden hose over their head. That could mean the rotational poles of the two stars might be pointed in our direction as well. When one of the stars ends its life as a supernova the explosion might be energetic enough to create a GRB that would beam in the polar directions. Since it is located right here in our own Galaxy, and seemed to be aimed right at us, at the time, WR 104 gained a second nickname – the ‘Death Star’.

Hill’s research, published in the Monthly Notices of the Royal Astronomical Society, is based on spectroscopy using three of Keck Observatory’s instruments – the Low Resolution Imaging Spectrometer (LRIS), the Echellette Spectrograph and Imager (ESI), and the Near-Infrared Spectrograph (NIRSPEC). With these spectra, he was able to measure velocities for the two stars, calculate their orbit and identify features in the spectra arising from the colliding winds. There turned out to be a very big surprise in store though.

“Our view of the pinwheel dust spiral from Earth absolutely looks face-on (spinning in the plane of the sky), and it seemed like a pretty safe assumption that the two stars are orbiting the same way” says Hill. “When I started this project, I thought the main focus would be the colliding winds and a face-on orbit was a given. Instead, I found something very unexpected. The orbit is tilted at least 30 or 40 degrees out of the plane of the sky.”

While a relief for those worried about a nearby GRB pointed right at us, this represents a real curveball. How can the dust spiral and the orbit be tilted so much to each other? Are there more physics that needs to be considered when modelling the formation of the dust plume?

“This is such a great example of how with astronomy we often begin a study and the universe surprises us with mysteries we didn’t expect” muses Hill. “We may answer some questions but create more. In the end, that is sometimes how we learn more about physics and the universe we live in. In this case, WR 104 is not done surprising us yet!”

Source: W.M. Keck ObservatoryScience News

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About NIRSPEC

The Near-Infrared Spectrograph (NIRSPEC) is a unique, cross-dispersed echelle spectrograph that captures spectra of objects over a large range of infrared wavelengths at high spectral resolution. Built at the UCLA Infrared Laboratory by a team led by Prof. Ian McLean, the instrument is used for radial velocity studies of cool stars, abundance measurements of stars and their environs, planetary science, and many other scientific programs. A second mode provides low spectral resolution but high sensitivity and is popular for studies of distant galaxies and very cool low-mass stars. NIRSPEC can also be used with Keck II’s adaptive optics (AO)system to combine the powers of the high spatial resolution of AO with the high spectral resolution of NIRSPEC. Support for this project was provided by the Heising-Simons Foundation.

About LRIS

The Low Resolution Imaging Spectrometer (LRIS) is a very versatile and ultra-sensitive visible-wavelength imager and spectrograph built at the California Institute of Technology by a team led by Prof. Bev Oke and Prof. Judy Cohen and commissioned in 1993. Since then it has seen two major upgrades to further enhance its capabilities: the addition of a second, blue arm optimized for shorter wavelengths of light and the installation of detectors that are much more sensitive at the longest (red) wavelengths. Each arm is optimized for the wavelengths it covers. This large range of wavelength coverage, combined with the instrument’s high sensitivity, allows the study of everything from comets (which have interesting features in the ultraviolet part of the spectrum), to the blue light from star formation, to the red light of very distant objects. LRIS also records the spectra of up to 50 objects simultaneously, especially useful for studies of clusters of galaxies in the most distant reaches, and earliest times, of the universe. LRIS was used in observing distant supernovae by astronomers who received the Nobel Prize in Physics in 2011 for research determining that the universe was speeding up in its expansion

About ESI

The Echellette Spectrograph and Imager (ESI) is a medium-resolution visible-light spectrograph that records spectra from 0.39 to 1.1 microns in each exposure. Built at UCO/Lick Observatory by a team led by Prof. Joe Miller, ESI also has a low-resolution mode and can image in a 2 x 8 arc min field of view. An upgrade provided an integral field unit that can provide spectra everywhere across a small, 5.7 x4.0 arc sec field. Astronomers have found a number of uses for ESI, from observing the cosmological effects of weak gravitational lensing to searching for the most metal-poor stars in our galaxy.

About W. M. KECK OBSERVATORY

The W. M. Keck Observatory telescopes are among the most scientifically productive on Earth. The two 10-meter optical/infrared telescopes atop Maunakea on the Island of Hawaii feature a suite of advanced instruments including imagers, multi-object spectrographs, high-resolution spectrographs, integral-field spectrometers, and world-leading laser guide star adaptive optics systems. Some of the data presented herein were obtained at Keck Observatory, which is a private 501(c) 3 non-profit organization operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. The authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Maunakea has always had within the Native Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain. For more information, visit: www.keckobservatory.org

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Webb Watches Carbon-Rich Dust Shells Form, Expand in Star System

Compare Observations of Wolf-Rayet 140 (MIRI Images)
Credits/Image: NASA, ESA, CSA, STScI
Science: Emma Lieb (University of Denver), Ryan Lau (NSF's NOIRLab), Jennifer Hoffman (University of Denver)

Wolf-Rayet 140 (MIRI Compass Image)
Credits/Image: NASA, ESA, CSA, STScI
Science: Emma Lieb (University of Denver), Ryan Lau (NSF's NOIRLab), Jennifer Hoffman (University of Denver)

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Fade Between 2022 and 2023 Observations of Wolf-Rayet 140
Credits/Video: NASA, ESA, CSA, STScI, Joseph DePasquale (STScI)
Science: Emma Lieb (University of Denver), Ryan Lau (NSF's NOIRLab), Jennifer Hoffman (University of Denver)

Stars’ Orbits in Wolf-Rayet 140 (Visualization)
Credits/Animation: NASA, ESA, CSA, Joseph Olmsted (STScI)

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Astronomers have long tried to track down how elements like carbon, which is essential for life, become widely distributed across the universe. Now, NASA’s James Webb Space Telescope has examined one ongoing source of carbon-rich dust in our own Milky Way galaxy in greater detail: Wolf-Rayet 140, a system of two massive stars that follow a tight, elongated orbit.
As they swing past one another (within the central white dot in the Webb images), the stellar winds from each star slam together, the material compresses, and carbon-rich dust forms. Webb’s latest observations show 17 dust shells shining in mid-infrared light that are expanding at regular intervals into the surrounding space.

“The telescope not only confirmed that these dust shells are real, its data also showed that the dust shells are moving outward at consistent velocities, revealing visible changes over incredibly short periods of time,” said Emma Lieb, the lead author of the new paper and a doctoral student at the University of Denver in Colorado.

Every shell is racing away from the stars at more than 1,600 miles per second (2,600 kilometers per second), almost 1% the speed of light. “We are used to thinking about events in space taking place slowly, over millions or billions of years,” added Jennifer Hoffman, a co-author and a professor at the University of Denver. “In this system, the observatory is showing that the dust shells are expanding from one year to the next.”

Like clockwork, the stars’ winds generate dust for several months every eight years, as the pair make their closest approach during a wide, elongated orbit. Webb also shows how dust formation varies — look for the darker region at top left in both images.

The telescope’s mid-infrared images detected shells that have persisted for more than 130 years. (Older shells have dissipated enough that they are now too dim to detect.) The researchers speculate that the stars will ultimately generate tens of thousands of dust shells over hundreds of thousands of years.

“Mid-infrared observations are absolutely crucial for this analysis, since the dust in this system is fairly cool. Near-infrared and visible light would only show the shells that are closest to the star,” explained Ryan Lau, a co-author and astronomer at NSF NOIRLab in Tuscon, Arizona, who led the initial research about this system. “With these incredible new details, the telescope is also allowing us to study exactly when the stars are forming dust — almost to the day.”

The dust’s distribution isn’t uniform. Though this isn’t obvious at first glance, zooming in on the shells in Webb’s images reveals that some of the dust has “piled up,” forming amorphous, delicate clouds that are as large as our entire solar system. Many other individual dust particles float freely. Every speck is as small as one-hundredth the width of a human hair. Clumpy or not, all of the dust moves at the same speed and is carbon rich.

The Future of This System

What will happen to these stars over millions or billions of years, after they are finished “spraying” their surroundings with dust? The Wolf-Rayet star in this system is 10 times more massive than the Sun and nearing the end of its life. In its final “act,” this star will either explode as a supernova — possibly blasting away some or all of the dust shells — or collapse into a black hole, which would leave the dust shells intact.

Though no one can predict with any certainty what will happen, researchers are rooting for the black hole scenario. “A major question in astronomy is, where does all the dust in the universe come from?” Lau said. “If carbon-rich dust like this survives, it could help us begin to answer that question.”

“We know carbon is necessary for the formation of rocky planets and solar systems like ours,” Hoffman added. “It’s exciting to get a glimpse into how binary star systems not only create carbon-rich dust, but also propel it into our galactic neighborhood.”

These results have been published in the Astrophysical Journal Letters and were presented in a press conference at the 245th meeting of the American Astronomical Society in National Harbor, Maryland.

The James Webb Space Telescope is the world’s premier space science observatory. Webb will solve mysteries in our solar system, look beyond to distant worlds around other stars, and probe the mysterious structures and origins of our universe and our place in it. Webb is an international program led by NASA with its partners, ESA (European Space Agency) and the Canadian Space Agency.

Source: NASA's James Webb Space Telescope/News

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About This Release

Credits:

Media Contact:

Claire Blome
Space Telescope Science Institute, Baltimore, Maryland

Christine Pulliam
Space Telescope Science Institute, Baltimore, Maryland

Science: Emma Lieb (University of Denver)

Permissions: Content Use Policy

Contact Us: Direct inquiries to the News Team.

Related Links and Documents

• 3D Print Files of Wolf-Rayet 140

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The exotic stellar population of Westerlund 1

Westerlund 1

A dense cluster of bright stars, each with six large and two small diffraction spikes, due to the telescope’s optics. They have a variety of sizes depending on their brightness and distance from us in the cluster, and different colours reflecting different types of star. Patches of billowing red gas can be seen in and around the cluster, lit up by the stars. Small stars in the cluster blend into a background of distant stars and galaxies on black. Credit: ESA/Webb, NASA & CSA, M. Zamani (ESA/Webb), M. G. Guarcello (INAF-OAPA) and the EWOCS team

The open cluster Westerlund 1, showcased in this new Webb Picture of the Month, is located roughly 12 000 light-years away in the southern constellation Ara (the Altar) where it resides behind a huge interstellar cloud of gas and dust. It was discovered in 1961 from Australia by Swedish astronomer Bengt Westerlund. Westerlund 1 is an incomparable natural laboratory for the study of extreme stellar physics, helping astronomers to find out how the most massive stars in our Galaxy live and die.

The unique draw of Westerlund 1 is its large, dense, and diverse population of massive stars, which has no counterpart in other known Milky Way galaxy clusters in terms of the number of stars and the richness of spectral types and evolutionary phases. All stars identified in this cluster are evolved and very massive, spanning the full range of stellar classifications including Wolf-Rayet stars, OB supergiants, yellow hypergiants (nearly as bright as a million Suns) and luminous blue variables. Because such stars have a rather short life, Westerlund 1 is very young, astronomically speaking. Astronomers estimate the cluster’s age to be somewhere between 3.5 and 5 million years (its exact age is still a matter of debate), making it a newborn cluster in our galaxy. In the future, it is believed that it will likely evolve from an open cluster into a globular cluster. These are roughly spherical, tightly packed collections of old stars bound together by gravity.

Currently, only a handful of stars form in our galaxy each year, but in the past the situation was different. The Milky Way galaxy used to produce many more stars, likely hitting its peak of churning out dozens or hundreds of stars per year about 10 billion years ago and then gradually declining ever since. Astronomers think that most of this star formation took place in massive clusters of stars, known as “super star clusters”. These are young clusters of stars that contain more than 10,000 times the mass of the Sun, packed into an unbelievably small volume. They represent the most extreme environments in which stars and planets can form. Only a few super star clusters still exist in our galaxy — of which Westerlund 1 is one — but they offer important clues about this earlier era when most of our galaxy’s stars formed.

Westerlund 1 is an impressive example of a super star cluster: it contains hundreds of very massive stars, some shining with a brilliance of almost one million Suns and others two thousand times larger than the Sun (as large as the orbit of Saturn). Indeed, if the Solar System was located at the heart of this remarkable cluster, our sky would be full of hundreds of stars as bright as the full Moon. It appears to be the most massive compact young cluster yet identified in the Milky Way galaxy: astronomers believe that this extreme cluster contains between 50 000 and 100 000 times the mass of the Sun, yet all of its stars are located within a region less than six light-years across. Even so, it is the biggest of these remaining super star clusters in the Milky Way galaxy, and the closest super star cluster to Earth. These qualities make Westerlund 1 an excellent target for studying the impact of a super star cluster’s environment on the formation process of stars and planets, as well as the evolution of stars over a broad range of masses.

The huge population of massive stars in Westerlund 1 suggests that it will have a very significant impact on its surroundings. The cluster contains so many massive stars that in a time span of less than 40 million years, it will be the site of more than 1 500 supernovae. This super star cluster now provides astronomers with a unique perspective towards one of the most extreme environments in the Universe. Westerlund 1 will certainly provide new opportunities in the long-standing quest for more and finer details about how stars, and especially massive stars, form.

This image was captured as part of the The Extended Westerlund 1 and 2 Open Clusters Survey (EWOCS) with Webb’s Near-InfraRed Camera (NIRCam). This survey is a dedicated Webb program (GO 1905, PI: M. G. Guarcello) that aims to study star and planet formation and stellar evolution in starburst regions in Westerlund 1 and Westerlund 2, two of the closest super star clusters to the Sun.

With its unparalleled performance in the infrared, Webb offers astronomers the opportunity to unveil the population of low-mass stars in local super star clusters for the first time, and to study the environments around these clusters’ most massive stars. Webb observations of the massive stars in super star clusters can shed light on how feedback (stellar winds, supernovae and other ejected material) from these stars impacts their surrounding environments and the overall star formation process within their parental clouds.

Links

• Westerlund 1 (wide-field view)
• Pan Video: Westerlund 1

Source: ESA/Webb/potm

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Astronomers Find Progenitor of Magnetic Monster

PR Image noirlab2323a

Artist’s impression of a highly unusual star that may evolve into a magnetar

PR Image noirlab2323b

Infographic: Evolution of a massive magnetic helium star into a magnetar

PR Image noirlab2323c

Artist Impression of Newly Formed Magentar

PR Image noirlab2323d

Massive Magnetic Helium Star Goes Supernova

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Videos

 

PR Video noirlab2323a

Interview with NOIRLab Astronomer André-Nicolas Chené

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Research team including NOIRLab astronomer identify highly unusual star that may evolve into a magnetar — the most magnetic object in the known Universe

A team of researchers, including NOIRLab astronomer André-Nicolas Chené, has found a highly unusual star that has the most powerful magnetic field ever found in a massive star — and that may become one of the most magnetic objects in the Universe: a variant of a neutron star known as a magnetar. This finding marks the discovery of a new type of astronomical object — a massive magnetic helium star — and sheds light on the origin of magnetars.

Neutron stars, the compact remains of a massive star following a supernova explosion, are the densest matter in the Universe. Some neutron stars, known as magnetars, also claim the record for the strongest magnetic fields of any object. How magnetars, which are a mere 15 kilometers across, form and produce such colossal magnetic fields remains a mystery.

New observations by a team of astronomers, including NSF’s NOIRLab’s André-Nicolas Chené, may shed important light on the origin of these magnetic powerhouses. Using various telescopes around the globe, including the Canada-France-Hawai‘i Telescope (CFHT) on Maunakea [1], the researchers have identified a new type of astronomical object — a massive magnetic helium star (an unusual variant of a Wolf-Rayet star), which may be the precursor of a magnetar.

“For the first time, a strong magnetic field was discovered in a massive helium star,” said Chené. “Our study suggests that this helium star will end its life as a magnetar.”

Despite having been observed for more than a century by astronomers, little was known about the true nature of this star, known as HD 45166, beyond the fact that it is rich in helium, somewhat more massive than our Sun, and part of a binary system.

“This star became a bit of an obsession of mine,” said Tomer Shenar, an astronomer at the University of Amsterdam and lead author of a study published in the journal Science. Having studied similar helium-rich stars before, Shenar was intrigued by the unusual characteristics of HD 45166, which has some of the characteristics of a Wolf-Rayet star, but with a unique spectral signature. He suspected that magnetic fields could explain these perplexing characteristics. "I remember having a Eureka moment while reading the literature: ‘What if the star is magnetic?’,” he said.

Shenar, Chené, and their collaborators set out to test this hypothesis by taking new spectroscopic observations of this star system with the CFHT. These observations revealed that this star has a phenomenally powerful magnetic field, about 43,000 gauss [2], the most powerful magnetic field ever found in a massive star. By also studying its interactions with its companion star, the team were able to make precise estimates of its mass and age.

The researchers speculate that, unlike other helium stars that eventually evolve from a red supergiant, this particular star was likely created by the merger of a pair of intermediate-mass stars.

“This is a very specific scenario, and it raises the question of how many magnetars come from similar systems and how many come from other types of systems,” said Chené.

In a few million years, HD 45166, which is located 3000 light-years away in the constellation Monoceros (the Unicorn), will explode as a very bright, but not particularly energetic, supernova. During this explosion, its core will contract, trapping and concentrating the star’s already daunting magnetic field lines. The result will be a neutron star with a magnetic field of around 100 trillion gauss — the most powerful type of magnet in the Universe.

“We thought that the most likely magnetar candidates would come from the most massive of stars,” said Chené. “What this research shows us is that stars that are much less massive can still become a magnetar, if the conditions are just right.”

Source: NSF’s National Optical-Infrared Astronomy Research Laboratory (NOIRLab)/News

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More Information

[1] The team also relied on key archive data taken with the Fiber-fed Extended Range Optical Spectrograph (FEROS) at ESO’s La Silla Observatory in Chile.

[2] Gauss is a unit of measurement of magnetic induction, also known as magnetic flux density (essentially, a measure of magnetic strength). The Sun’s typical polar magnetic field is 1–2 gauss, while sunspots can achieve a magnetic field strength of around 3000 gauss.

Reference: Shenar, T., Wade, G., Marchat, P., et al. 2023, A massive helium star with a sufficiently strong magnetic field to form a magnetar, Science, DOI 10.1126.

NSF’s NOIRLab, the US center for ground-based optical-infrared astronomy, operates the international Gemini Observatory (a facility of NSF, NRC–Canada, ANID–Chile, MCTIC–Brazil, MINCyT–Argentina, and KASI–Republic of Korea), Kitt Peak National Observatory (KPNO), Cerro Tololo Inter-American Observatory (CTIO), the Community Science and Data Center (CSDC), and Vera C. Rubin Observatory (operated in cooperation with the Department of Energy’s SLAC National Accelerator Laboratory). It is managed by the Association of Universities for Research in Astronomy (AURA) under a cooperative agreement with NSF and is headquartered in Tucson, Arizona. The astronomical community is honored to have the opportunity to conduct astronomical research on Iolkam Du’ag (Kitt Peak) in Arizona, on Maunakea in Hawai‘i, and on Cerro Tololo and Cerro Pachón in Chile. We recognize and acknowledge the very significant cultural role and reverence that these sites have to the Tohono O'odham Nation, to the Native Hawaiian community, and to the local communities in Chile, respectively.

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Links

• Research paper
• ESO version of release
• Canada-France-Hawaii Telescope release

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Contacts:

Charles Blue
NSF’s NOIRLab
Tel: +1 202 236 6324
Email: charles.blue@noirlab.edu

André-Nicolas Chené
NSF's NIORLab
Email: andre-nicolas.chene@noirlab.edu

Tomer Shenar
University of Amsterdam
Email: t.shenar@uva.nl

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