Wednesday, November 29, 2023

Extreme stars share unique properties that may provide a link to mysterious sources

Fig. 1: Artistic impression of a magnetar, where a neutron star emits radio light powered by the energy stored in the ultra-strong magnetic field, causing outburst which are among the most powerful events observed in the Universe. © Michael Kramer / MPIfR 
A universal relation for pulsars, magnetars and potentially fast radio bursts

An international research team led by Michael Kramer and Kuo Liu from the Max Planck Institute for Radio Astronomy in Bonn, Germany, have studied a rare species of ultra-dense stars, so called magnetars, to uncover an underlying law that appears to apply universally to a range of objects known as neutron stars. This law gives insight into how these sources produce radio emission and it may provide a link to the mysterious flashes of radio light, Fast Radio Bursts, that originate from the distant cosmos. The results are published in this week’s issue of Nature Astronomy.

Neutron stars are the collapsed cores of massive stars, concentrating up to twice the mass of the sun in a sphere of less than 25 km diameter. As a result, the matter there is the most densely packed one in the observable Universe, squeezing electrons and protons into neutrons, hence the name. More than 3000 neutron stars can be observed as radio pulsars, when they emit a radio beam that is visible as a pulsating signal from Earth, when the rotating pulsar shines its light towards our telescopes.

The magnetic field of pulsars is already a thousand billion times stronger than the magnetic field of the Earth, but there is a small group of neutron stars that have magnetic fields even 1000 times stronger still! These are the so called magnetars. Of the about 30 magnetars known, six have also been detected to emit radio emission, at least occasionally. Extragalactic magnetars have been suggested to be the origin of the Fast Radio Bursts (FRBs), and in order to study this link, researchers from the Max Planck Institute for Radio Astronomy (MPIfR) with help from colleagues at the University of Manchester, have inspected the individual pulses of magnetars in details and detected sub-structure in those. It turns out that similar pulse structure was also seen in pulsars, the fast-rotating millisecond pulsars, and in other neutron star sources known as Rotating Radio Transients.

To their surprise, the researchers found that the timescale of magnetars and that of the other types of neutron stars all follow the same universal relationship, scaling exactly with the rotation period. The fact that a neutron star with a rotation period of less than a few milliseconds and one with a period of nearly 100 seconds behave like magnetars suggests that the intrinsic origin of the subpulse structure must be the same for all radio-loud neutron stars. It reveals information about the plasma process responsible for the radio emission itself, and it offers a change to interpret similar structure seen in FRBs as the result of a corresponding rotational period.

“When we set out to compare magnetar emission with that of FRBs, we expected similarities,” recalls Michael Kramer, first author of the paper and Director at MPIfR. “What we didn’t expect is that all radio-loud neutron stars share this universal scaling.”

“We expect magnetars to be powered by magnetic field energy, while the others are powered by their rotational energy,” complements Kuo Liu. “Some are very old, some are very young, and yet all seem to follow this law.”

Gregory Desvignes describes the experiment: “We observed the magnetars with the 100-m radio telescope in Effelsberg and compared our result also to archival data, since magnetars do not emit radio emission all the time.” “Since magnetar radio emission is not always present, one needs to be flexible and react quickly, which is possible with telescopes like the one in Effelsberg,” confirms Ramesh Karuppusamy.

For Ben Stappers, co-author of the study, the most exciting aspect of the result is the possible connection to FRBs: “If at least some FRBs originate from magnetars, the timescale of the substructure in the burst might then tell us the rotation period of the underlying magnetar source. If we find this periodicity in the data, this would be a milestone in explaining this type of FRB as radio sources.”

“With this information, the search is on!”, concludes Michael Kramer.

Additional Information

Magnetars are among the most energetic neutron stars attributed to their extremely high magnetic fields. Out of the above thirty magnetars discovered so far, only six are known to exhibit radio emission. Recently, research interest in their properties has drastically increased due to their possible link to fast radio bursts (FRBs). FRBs are millisecond-long bursts of radio emission generated by extra-galactic sources. Though the origin of these radio bursts has not been understood, magnetars are speculated to be one of the possible FRB sources.

Sub-structure with short-duration, concentrated emission was detected in the radio signal of pulsars soon after their first discovery. Typically, the sub-structure has a characteristic quasi-periodicity and width, both of which have been found to scale with the rotational period of the pulsar. This relation has been established in canonical pulsars for decades, and expanded to the millisecond pulsar population in recent years. Very recently, the same type of short-duration ‘micro-pulse’ has also been seen in some FRBs, indicating the presence of a similar underlying emission process in both scenarios.

The research used observations of all six radio-loud magnetars which were carried out by the Effelsberg 100-m telescope at CX band (4-8 GHz) and a few other 100-m class radio telescopes around the globe.


Prof. Dr. Michael Kramer
Director and Head of „Fundamental Physics in Radio Astronomy“ Research Dept.
tel:+49 228 525-299
Max Planck Institute for Radio Astronomy, Bonn

Dr. Kuo Liu
tel:+49 228 525-324
Max Planck Institute for Radio Astronomy, Bonn

Dr. Norbert Junkes
Press and Public Outreach
tel:+49 228 525-399
Max Planck Institute for Radio Astronomy, Bonn

Original Paper

Quasi-periodic sub-pulse structure as a unifying feature for radio-emitting neutron stars
M. Kramer et al., in Nature Astronomy, 23 November 2023


Fundamental Physics in Radio Astronomy
Research Department at MPIfR

Radio Telescope Effelsberg
Effelsberg 100-m Radio Telescope

Tuesday, November 28, 2023

One cluster or two?

A cluster of galaxies, concentrated around what appear to be two large elliptical galaxies. The rest of the black background is covered in smaller galaxies of all shapes and sizes. In the top left and bottom right, beside the two large galaxies, some galaxies appear notably distorted into curves by gravity. Credit: ESA/Hubble & NASA, G. Smith, H. Ebeling, D. Coe

This Hubble Picture of the Week features a massive cluster of brightly glowing galaxies, first identified as Abell 3192. Like all galaxy clusters, this one is suffused with hot gas that emits powerful X-rays, and it is enveloped in a halo of invisible dark matter. All this unseen material — not to mention the many galaxies visible in this image — comprises such a huge amount of mass that the galaxy cluster noticeably curves spacetime around it, making it into a gravitational lens. Smaller galaxies behind the cluster appear distorted into long, warped arcs around the cluster’s edges.

The galaxy cluster is located in the constellation Eridanus, but the question of its distance from Earth is a more complicated one. Abell 3192 was originally documented in the 1989 update of the Abell catalogue, a catalogue of galaxy clusters that was first published in 1958. At that time, Abell 3192 was thought to comprise a single cluster of galaxies, concentrated at a single distance. However, further research revealed something surprising: the cluster’s mass seemed to be densest at two distinct points rather than one.

It was subsequently shown that the original Abell cluster actually comprised two independent galaxy clusters — a foreground group around 2.3 billion light-years from Earth, and a further group at the greater distance of about 5.4 billion light-years from our planet. The more distant galaxy cluster, included in the Massive Cluster Survey as MCS J0358.8-2955, is central in this image. The two galaxy groups are thought to have masses equivalent to around 30 trillion and 120 trillion times the mass of the Sun, respectively. Both of the two largest galaxies at the centre of this image are part of MCS J0358.8-2955; the smaller galaxies you see here, however, are a mixture of the two groups within Abell 3192.


Monday, November 27, 2023

New Indian telescope identifies its first supernova

A small segment (size: 6 arcmin × 6 arcmin) of a single image frame (102 sec integration time) obtained with the ILMT is displayed. The location of SN 2023af is marked with a white crosshair. Credit: arXiv (2023). DOI: 10.48550/arxiv.2311.05618

A newly built International Liquid Mirror Telescope (ILMT) in India has identified its first supernova—designated SN 2023af. The finding, reported November 8 on the pre-print server arXiv, proves that ILMT may be capable of detecting hundreds of new supernovae in the coming years.

A small segment (size: 6 arcmin × 6 arcmin) of a single image frame (102 Supernovae (SNe) are powerful and luminous stellar explosions that could help us better understand the evolution of stars and galaxies. Astronomers divide supernovae into two groups based on their atomic spectra: Type I and Type II. Type I SNe lack hydrogen in their spectra, while those of Type II showcase spectral lines of hydrogen.

ILMT is a 4-m diameter zenith-pointing telescope located at Devasthal Observatory in Nainital, India. It is entirely dedicated to conduct photometric/astrometric direct imaging surveys. Astronomers hope that ILMT will help them detect many new transient objects such as supernovae of gamma-ray bursts. The telescope saw the first light on April 29, 2022, and is currently in the advanced stage of commissioning.

Now, a team of led by Brajesh Kumar of the Aryabhatta Research Institute of Observational sciencES (ARIES) in India, reports that ILMT has spotted its first on March 9, 2023—SN 2023af, which was initially detected two months earlier. The team conducted follow-up observations of SN 2023af using ILMT, as well as the 3.6m Devasthal Optical Telescope (DOT) and the 1.3m Devasthal Fast Optical Telescope (DFOT).

"During the commissioning phase of the ILMT, supernova (SN) 2023af was identified in the ILMT field of view. The SN was further monitored with the ILMT and DOT facilities," the researchers wrote.

The team obtained a of SN 2023af spanning up to 110 days after its discovery. Initial results from ILMT show that hydrogen lines are clearly visible and metal lines also appear in the spectra of this supernova.

Based on the light curve and spectral features of SN 2023af, the authors of the paper suppose that the object as a Type IIP supernova. In general, the type II-Plateau supernovae (SNe IIP) remain bright (on a plateau) for an extended period of time after maximum. This plateau in the light curve of a standard SN IIP typically lasts about 100 days.

It is assumed that SNe IIP like SN 2023af originate from precursor stars that retain a substantial amount of their hydrogen layers (greater than three ) before exploding as (CCSNe).

However, the astronomers added that complementary observations of SN 2023af are needed in order to confirm its Type IIP classification. They explained that a definite conclusion about the plateau length of this supernova is not possible at the moment due to the sparse data points.

Summing up the results, the researchers noted that future ILMT observations will provide a unique opportunity to discover and study different types of supernovae each year, leading to the detection of hundreds of new stellar explosions.

More information:

Brajesh Kumar et al, Follow-up strategy of ILMT discovered supernovae, arXiv (2023).
DOI: 10.48550/arxiv.2311.05618

Journal information: arXiv

Sunday, November 26, 2023

Sizing Up Neutron Stars with Gravitational Waves

An illustration of the gravitational waves created by two neutron stars approaching a merger.

Gravitational waves from colliding neutron stars have improved our understanding of the interiors of these fantastically compressed objects and helped us measure their radii. How much more precisely will we be able to measure neutron stars with future gravitational wave observatories?

This image from the Hubble Space Telescope shows a neutron star. It was estimated to be no more than 28 kilometers (16.8 miles) across and have a temperature of 1,200,000℉ (670,000℃). Credit: Fred Walter (State University of New York at Stony Brook) and NASA/ESA; CC BY 4.0

Measuring a Neutron Star

When stars more massive than about eight times the mass of the Sun explode as supernovae, they often leave behind a neutron star: the rapidly spinning, magnetized remnant of the star’s core. Neutron stars are immensely dense and strong, packing more than the mass of the Sun into a sphere the size of a city. Counterintuitively, the more massive the neutron star, the smaller it is. Exactly how a neutron star’s size varies with its mass is described by its equation of state: the relationship between mass, radius, and density.

Already, observations of gravitational waves from colliding neutron stars have helped us hone our estimates of the neutron star equation of state. A 1.4-solar-mass neutron star — around the lower limit of a neutron star’s mass — will have a radius between 10.5 and 13 kilometers. Researchers suspect that future gravitational wave observations will narrow this range further, and new work explores how precisely we’ll be able to measure neutron stars in the future.

Soft, medium, and stiff equations of state (blue, orange, and green lines, respectively), as well as the full set of equations of state used in the analysis. Credit: Finstad et al. 2023

Computing Collisions

To probe this question, Daniel Finstad (University of Washington; University of California, Berkeley; Lawrence Berkeley National Laboratory) and collaborators Laurel White and Duncan Brown (both Syracuse University) simulated the gravitational waves produced by many pairs of colliding neutron stars.

The team modeled three populations of colliding neutron stars with different equations of state, labeled “soft,” “medium,” and “stiff.” These equations of state cover the range of neutron star interiors currently allowed by observations. The stiffness of the equation of state affects both the neutron stars’ sizes and how much they’re deformed by tidal forces as they approach a collision. These changes leave an imprint on the gravitational waves produced in a collision, allowing us to extract the equation of state from gravitational wave observations. Modeling a range of equations of state is important because our ability to measure a neutron star’s equation of state depends on the equation of state itself; “soft” interiors produce signals that are fainter than “stiff” interiors do.

Number of years needed for LIGO–Virgo to observe enough mergers to measure the neutron star equation of state to a precision of 2%. Results are shown for stiff, medium, and soft equations of state (green, orange, and blue, respectively), as well as for different values for the neutron star merger rate, shown with the timescales at the top. Credit: Finstad et al. 2023

Upcoming Observations

With a suite of simulations in hand, Finstad’s team modeled what future gravitational wave observatories would detect if faced with these synthetic signals. They considered future upgrades to the Laser Interferometer Gravitational-Wave Observatory (LIGO) and Virgo detectors that would bring them up to their maximum sensitivity as well as the proposed Cosmic Explorer, which would have arms 10 times as long as LIGO’s and therefore be more sensitive.

Finstad and collaborators found that an upgraded LIGO-Virgo would be able to measure the neutron star equation of state to within a precision of 1.9–0.7%, depending on the stiffness — but it would take 10, 20, or 57 years to observe enough mergers of stiff, medium, or soft neutron stars (respectively) to reach that precision. Cosmic Explorer, on the other hand, would require only a year to amass a similarly large collection of observations, measuring the equation of state to within a precision of 0.56% or better.

By Kerry Hensley


“Prospects for a Precise Equation of State Measurement from Advanced LIGO and Cosmic Explorer,” Daniel Finstad et al 2023 ApJ 955 45. doi:10.3847/1538-4357/acf12f

Saturday, November 25, 2023

“Late-type” galaxy?

An irregular galaxy, a narrow streak of stars crossed by faint dust lanes. It is surrounded by a bright glow, appearing like a beam of light in the centre of a dark background. A scatter of small, distant galaxies and a single, bright star surround the galaxy. Credit: ESA/Hubble & NASA, C. Kilpatrick

This Hubble Picture of the Week features NGC 2814, an irregular galaxy that lies about 85 million light years from Earth. In this image, which was captured using Hubble’s Advanced Camera for Surveys (ACS), the galaxy appears to be quite isolated: visually, it looks a little like a loose stroke of bright paint across a dark background. However, looks can be deceiving. NGC 2814 actually has three close (in astronomical terms) galactic neighbours: a side-on spiral galaxy known as NGC 2820; an irregular galaxy named IC 2458; and a face-on non-barred spiral galaxy called NGC 2805. Collectively, the four galaxies make up a galaxy group known as Holmberg 124. In some literature these galaxies are referred to as a group of ‘late-type galaxies’.

The terminology ‘late-type’ refers to spiral and irregular galaxies, whilst ‘early-type’ refers to elliptical galaxies. This rather confusing terminology has led to a common misconception within the astronomy community. It is still quite widely believed that Edwin Hubble inaccurately thought that elliptical galaxies were the evolutionary precursors to spiral and irregular galaxies, and that that is the reason why ellipticals are classed as ‘early-type’ and spirals and irregulars are classed as ‘late-type’. This misconception is due to the Hubble ‘tuning fork’ of galactic classification, which visually shows galaxy types proceeding from elliptical to spiral, in a sequence that could easily be interpreted as a temporal evolution. However, Hubble actually adopted the terms ‘early-type’ and ‘late-type’ from much older astronomical terminology for stellar classifications, and did not mean to state that ellipticals were literally evolutionary precursors to spiral and irregular galaxies. In fact, he explicitly said in his 1927 paper that ‘the nomenclature … [early and late] … refers to position in the sequence, and temporal connotations are made at one’s peril’.

Despite Hubble himself being quite emphatic on this topic, the misunderstanding persists almost a hundred years later, and perhaps provides an instructive example of why it is helpful to classify things with easy-to-interpret terminology from the get-go!

Friday, November 24, 2023

NASA's Webb Reveals New Features in Heart of Milky Way

Sagittarius C (NIRCam Image)
Credits: Image: NASA, ESA, CSA, STScI, Samuel Crowe (UVA)

Sagittarius C (Annotated NIRCam Image)
Credits: Image: NASA, ESA, CSA, STScI, Samuel Crowe (UVA)

The latest image from NASA’s James Webb Space Telescope shows a portion of the dense center of our galaxy in unprecedented detail, including never-before-seen features astronomers have yet to explain. The star-forming region, named Sagittarius C (Sgr C), is about 300 light-years from the Milky Way’s central supermassive black hole, Sagittarius A*.

“There's never been any infrared data on this region with the level of resolution and sensitivity we get with Webb, so we are seeing lots of features here for the first time,” said the observation team’s principal investigator Samuel Crowe, an undergraduate student at the University of Virginia in Charlottesville. “Webb reveals an incredible amount of detail, allowing us to study star formation in this sort of environment in a way that wasn’t possible previously.”

“The galactic center is the most extreme environment in our Milky Way galaxy, where current theories of star formation can be put to their most rigorous test,” added professor Jonathan Tan, one of Crowe’s advisors at the University of Virginia.

Amid the estimated 500,000 stars in the image is a cluster of protostars – stars that are still forming and gaining mass – producing outflows that glow like a bonfire in the midst of an infrared-dark cloud. At the heart of this young cluster is a previously known, massive protostar over 30 times the mass of our Sun. The cloud the protostars are emerging from is so dense that the light from stars behind it cannot reach Webb, making it appear less crowded when in fact it is one of the most densely packed areas of the image. Smaller infrared-dark clouds dot the image, looking like holes in the starfield. That’s where future stars are forming.

Webb’s NIRCam (Near-Infrared Camera) instrument also captured large-scale emission from ionized hydrogen surrounding the lower side of the dark cloud, shown cyan-colored in the image. Typically, Crowe says, this is the result of energetic photons being emitted by young massive stars, but the vast extent of the region shown by Webb is something of a surprise that bears further investigation. Another feature of the region that Crowe plans to examine further is the needle-like structures in the ionized hydrogen, which appear oriented chaotically in many directions.

“The galactic center is a crowded, tumultuous place. There are turbulent, magnetized gas clouds that are forming stars, which then impact the surrounding gas with their outflowing winds, jets, and radiation,” said Rubén Fedriani, a co-investigator of the project at the Instituto Astrofísica de Andalucía in Spain. “Webb has provided us with a ton of data on this extreme environment, and we are just starting to dig into it.”

Around 25,000 light-years from Earth, the galactic center is close enough to study individual stars with the Webb telescope, allowing astronomers to gather unprecedented information on how stars form, and how this process may depend on the cosmic environment, especially compared to other regions of the galaxy. For example, are more massive stars formed in the center of the Milky Way, as opposed to the edges of its spiral arms?

“The image from Webb is stunning, and the science we will get from it is even better,” Crowe said. “Massive stars are factories that produce heavy elements in their nuclear cores, so understanding them better is like learning the origin story of much of the universe.”

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 the Canadian Space Agency.

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Leah Ramsay
Space Telescope Science Institute, Baltimore, Maryland

Christine Pulliam
Space Telescope Science Institute, Baltimore, Maryland

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Thursday, November 23, 2023

UHZ1: NASA Telescopes Discover Record-Breaking Black Hole

Credit: X-ray: NASA/CXC/SAO/Ákos Bogdán; Infrared: NASA/ESA/CSA/STScI;
Image Processing: NASA/CXC/SAO/L. Frattare & K. Arcand

This image contains the most distant black hole ever detected in X-rays, a result that may explain how some of the first supermassive black holes in the universe formed. As we report in our press release, this discovery was made using X-rays from NASA’s Chandra X-ray Observatory (purple) and infrared data from NASA’s James Webb Space Telescope (red, green, blue).

The extremely distant black hole is located in the galaxy UHZ1 in the direction of the galaxy cluster Abell 2744. The galaxy cluster is about 3.5 billion light-years from Earth. Webb data, however, reveal that UHZ1 is much farther away than Abell 2744. At some 13.2 billion light-years away, UHZ1 is seen when the universe was only 3% of its current age.

By using over two weeks of observations from Chandra, researchers were able to detect X-ray emission from UHZ1 — a telltale signature of a growing supermassive black hole in the center of the galaxy. The X-ray signal is extremely faint and Chandra was only able to detect it — even with this long observation — because of the phenomenon known as gravitational lensing that enhanced the signal by a factor of four.

The purple parts of the image show X-rays from large amounts of hot gas in Abell 2744. The infrared image shows hundreds of galaxies in the cluster, along with a few foreground stars. The insets zoom into a small area centered on UHZ1. The small object in the Webb image is the distant galaxy UHZ1 and the center of the Chandra image shows X-rays from material close to the supermassive black hole in the middle of UHZ1. The large size of the X-ray source compared to the infrared view of the galaxy is because it represents the smallest size that Chandra can resolve. The X-rays actually come from a region that is much smaller than the galaxy.

Different smoothing was applied to the full-field Chandra image and to the Chandra image in the close-up. Smoothing across many pixels was performed for the large image, to highlight the faint cluster emission, at the expense of not showing faint X-ray point sources like UHZ1. Much less smoothing was applied to the close-up so faint X-ray sources are visible. The image is oriented so that north points 42.5 degrees to the right of vertical.

This discovery is important for understanding how some supermassive black holes — those that contain up to billions of solar masses and reside in the centers of galaxies — can reach colossal masses soon after the big bang. Do they form directly from the collapse of massive clouds of gas, creating black holes weighing between about ten thousand and a hundred thousand suns? Or do they come from explosions of the first stars that create black holes weighing only between about ten and a hundred suns?

The team of astronomers found strong evidence that the newly discovered black hole in UHZ1 was born massive. They estimate its mass falls between 10 and 100 million suns, based on the brightness and energy of the X-rays. This mass range is similar to that of all the stars in the galaxy where it lives, which is in stark contrast to black holes in the centers of galaxies in the nearby universe that usually contain only about a tenth of a percent of the mass of their host galaxy’s stars.

The large mass of the black hole at a young age, plus the amount of X-rays it produces and the brightness of the galaxy detected by Webb, all agree with theoretical predictions in 2017 for an “Outsize Black Hole” that directly formed from the collapse of a huge cloud of gas.

Illustration: Formation of a Heavy Seed Black Hole from Direct Collapse of a Massive Cloud of Gas
Credit: NASA/STScI/Leah Hustak

The researchers plan to use this and other results pouring in from Webb and those combining data from other telescopes to fill out a larger picture of the early universe.

The paper describing the results appears in Nature Astronomy and a preprint is available online. The authors include Akos Bogdan (Center for Astrophysics | Harvard & Smithsonian), Andy Goulding (Princeton University), Priyamvada Natarajan (Yale University), Orsolya Kovacs (Masaryk University, Czech Republic), Grant Tremblay (CfA), Urmila Chadayammuri (CfA), Marta Volonteri (Institut d'Astrophysique de Paris, France), Ralph Kraft (CfA), William Forman (CfA), Chrisine Jones (CfA), Eugene Churazov (Max Planck Institute for Astrophysics, Germany), and Irina Zhuravleva (University of Chicago).

The Webb data used in both papers is part of a survey called the Ultradeep Nirspec and nirCam ObserVations before the Epoch of Reionization (UNCOVER). The paper led by UNCOVER team member Andy Goulding appears in the Astrophysical Journal Letters and a preprint is available online. The co-authors include other UNCOVER team members, plus Bogdan and Natarajan. A detailed interpretation paper that compares observed properties of UHZ1 with theoretical models for Outsize Black Hole Galaxies is currently under review and a preprint is available here.

NASA's Marshall Space Flight Center manages the Chandra program. The Smithsonian Astrophysical Observatory's Chandra X-ray Center controls science operations from Cambridge, Massachusetts, and flight operations from Burlington, Massachusetts.

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 Chandra X-Ray Observatory

Visual Description:

The main image of this release features a glimpse of a black hole in an early stage of its development, just 470 million years after the Big Bang.

The composite image shows data from NASA's Chandra X-ray Observatory and James Webb Space Telescope. It features scores of seemingly tiny celestial objects in a sea of black. This is the galaxy cluster Abell 2744. When magnified, the tiny white, orange, and purple celestial objects are revealed to be spiral and elliptical galaxies, and gleaming stars. Many of these colorful specks appear to float in a neon purple cloud of X-ray gas in the center of the image, some 3.5 billion light-years from Earth.

Just to the right of center, at the edge of the purple gas cloud, is a tiny orange speck. This speck is far in the distance, well beyond the Abell galaxy cluster. It represents a galaxy 13.2 billion light-years from Earth containing a supermassive black hole.

In this composite image packed with celestial objects, the tiny orange speck is easily overlooked. Therefore, the main image of the release is also presented fully labelled. In the labelled version of the image, a thin box outlines the distant galaxy, and two enlargements are inset at our upper left. In the enlargement showing Chandra data, a hazy, neon purple oval with a light pink core is shown. This purple oval represents intense X-rays from a growing supermassive black hole estimated to weigh between 10 and 100 million suns. The purple oval is not visible in the composite image because of the way the Chandra data was processed.

This black hole is located in the distant galaxy in the center of the enlargement showing Webb data.

Fast Facts for (UHZ1):

Scale: Image is about 6.7 arcmin (5.5 million light-years) across.
Category: Black Holes, Groups & Clusters of Galaxies
Coordinates (J2000): RA 00h 14m 16.1s | Dec -30° 22´ 40.3"
Constellation: Sculptor
Observation Dates: 60 observations from Sep 2001 to Jan 2023
Observation Time: 346 hours 27 minutes (14 days 10 hours 27 minutes)
Obs. ID 2212, 7712, 7915, 8477, 8557, 25278, 25279, 25907, 25908, 25910-25915, 25918-25920, 25922-25932, 25934, 25936-25939, 25942, 25944, 25945, 25948, 25951, 25953, 25954, 25956-25958, 25963, 25967-25973, 26280, 27347, 27449, 27450, 27556, 27575, 27678-27681
Instrument: ACIS
References: Bogdán, Á. et al; 2023, Nature Astronomy, accepted: arXiv:2305:15458;
Goulding, A. et al; 2023, ApJL, 955, L24, arXiv:2308.02750;
Natarajan, P. et al; 2023, ApJ, submitted: arXiv:2308:02654
Color Code: X-ray: purple; Infrared: red, green, blue
Distance Estimate: About 13.2 billion light-years (z=10.1)

Wednesday, November 22, 2023

NASA's Hubble Measures the Size of the Nearest Transiting Earth-Sized Planet

Exoplanet LTT 1445Ac (Artist's Concept)
Credits: Artwork: NASA, ESA, Leah Hustak (STScI)

Comparison of Transit Paths (Artist's Concept)
Credits: Artwork: NASA, ESA, Elizabeth Wheatley (STScI)

NASA's Hubble Space Telescope has measured the size of the nearest Earth-sized exoplanet that passes across the face of a neighboring star. This alignment, called a transit, opens the door to follow-on studies to see what kind of atmosphere, if any, the rocky world might have.

The diminutive planet, LTT 1445Ac, was first discovered by NASA's Transiting Exoplanet Survey Satellite (TESS) in 2022. But the geometry of the planet's orbital plane relative to its star as seen from Earth was uncertain because TESS does not have the required optical resolution. This means the detection could have been a so-called grazing transit, where a planet only skims across a small portion of the parent star's disk. This would yield an inaccurate lower limit of the planet's diameter.

"There was a chance that this system has an unlucky geometry and if that's the case, we wouldn't measure the right size. But with Hubble's capabilities we nailed its diameter," said Emily Pass of the Center for Astrophysics | Harvard & Smithsonian in Cambridge, Massachusetts.

Hubble observations show that the planet makes a normal transit fully across the star's disk, yielding a true size of only 1.07 times Earth's diameter. This means the planet is a rocky world, like Earth, with approximately the same surface gravity. But at a surface temperature of roughly 500 degrees Fahrenheit, it is too hot for life as we know it.

The planet orbits the star LTT 1445A, which is part of a triple system of three red dwarf stars that is 22 light-years away in the constellation Eridanus. The star has two other reported planets that are larger than LTT 1445Ac. A tight pair of two other dwarf stars, LTT 1445B and C, lies about 3 billion miles away from LTT 1445A, also resolved by Hubble. The alignment of the three stars and the edge-on orbit of the BC pair suggests that everything in the system is co-planar, including the known planets.

"Transiting planets are exciting since we can characterize their atmospheres with spectroscopy, not only with Hubble but also with the James Webb Space Telescope . Our measurement is important because it tells us that this is likely a very nearby terrestrial planet. We are looking forward to follow-on observations that will allow us to better understand the diversity of planets around other stars," said Pass.

This research is published in The Astronomical Journal.

The Hubble Space Telescope is a project of international cooperation between NASA and ESA. NASA's Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore, Maryland, conducts Hubble and Webb science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy, in Washington, D.C.

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Tuesday, November 21, 2023

Gemini North Peers Deeper Into the Dust with New Instrument

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IGRINS-2 First-Light spectrum

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IGRINS-2 captures spectrum of Jewel Bug Nebula

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The blue IGRINS-2 spectrum (no labels)

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The red IGRINS-2 spectrum (no labels)

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KASI and Gemini IGRINS-2 team photo on the night of first light

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IGRINS-2 on Gemini North Telescope

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The blue IGRINS-2 spectrum (with labels)

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The red IGRINS-2 spectrum (with labels)

Image Comparisons

The blue IGRINS-2 spectrum with and without labels
The blue IGRINS-2 spectrum with and without labels

The red IGRINS-2 spectrum with and without labels
The red IGRINS-2 spectrum with and without labels


Gemini North Observing  
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Gemini North Observing

Gemini North Observing  
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Gemini North Observing

IGRINS-2, a new high-resolution near-infrared spectrograph on Gemini North, sees First Light

Gemini North, one half of the International Gemini Observatory operated by NSF’s NOIRLab, is now peering deeper into the dusty dwellings of young stars with its new IGRINS-2 instrument. This next-generation spectrograph is an upgraded version of the high-demand visiting instrument IGRINS on Gemini South that will expand our understanding of cosmic objects shrouded by dust and gas.

IGRINS-2 (Immersion GRating INfrared Spectrograph-2) has set its ‘eyes’ on the sky for the first time. Mounted on the Gemini North telescope, one half of the International Gemini Observatory operated by NSF’s NOIRLab, the new instrument obtained spectra of the planetary nebula NGC 7027, nicknamed the Jewel Bug Nebula. NGC 7027 is one of the visually brightest planetary nebulae, and its resplendent rosette — made of layers of gas ejected during the dying breaths of its central star — makes for an exciting first light target.

Spectrographs are arguably the most important science instruments in all of astronomy. Unlike high-resolution cameras that capture amazing details of distant stars, galaxies and nebulae, spectrographs precisely analyze the spectrum of light emitted by these objects, revealing detailed information about their chemical composition. The expansion of NGC 7027’s dynamic gasses out into the surrounding space produces a striking spectrum that illustrates the power of the instrument.

With the new infrared IGRINS-2 on Gemini North complementing the new optical GHOST on Gemini South, we now have two cutting-edge high-resolution spectrographs,” said Jennifer Lotz, Director of Gemini Observatory. “This expanded capability of our observatory opens up exciting windows of discovery.

Although its first spectrum is of the death throes of a star, IGRINS-2 is actually designed to witness the first moments of nascent stars. “The main science goal of IGRINS-2 is observing young stars being born inside a dusty environment,” said IGRINS-2 Project Manager and Technical Representative Hwihyun Kim. While these dusty birthplaces are impenetrable to visible light, a near-infrared spectrograph like IGRINS-2 can pierce through the dust and observe young stars in their early development.

With its ability to see through gas, dust, and other opaque materials, IGRINS-2 is also well-suited to studying brown dwarfs, exoplanets, the interstellar medium and the evolution of galaxies. Not only is IGRINS-2 able to see through dust, it does so with remarkable resolution, allowing astronomers to resolve details about stellar atmospheres and the structures of galaxies.

IGRINS-2 was built by the Korea Astronomy and Space Science Institute (KASI) on behalf of the International Gemini Observatory. Initiated in March 2020, this instrument was constructed during the COVID-19 pandemic. “It has been gratifying to see our efforts come to fruition,” said KASI Principal Investigator Chan Park. “We delivered this instrument and its components without any delays — all in the middle of a global pandemic — thanks to the valiant efforts of our team and our partners at Gemini Observatory.

During the highly-anticipated first-light event, excitement filled the Gemini North control room as IGRINS-2 captured its first spectra. “It’s difficult to describe the emotion of people when they saw the first observations; it was a mix of excitement, awe, relief, and joy,” said Ruben Diaz, Gemini’s acting Associate Director of Development. Kim adds that she was told by her Gemini North colleagues they had never seen so many people in the control room at one time.

Following this significant milestone, the KASI and Gemini teams will begin integrating IGRINS-2 with the software and subsystems at Gemini North, a process that will take several months. Gemini staff will then be trained in maintaining and operating the instrument. In addition, documentation will be developed to assist the user community with the instrument. IGRINS-2 will be available for use by the broader astronomy community in the second half of 2024.

“The ability of IGRINS-2 to peer within otherwise opaque regions of the Universe will allow us to better understand how stars are born and many other astronomical phenomena hidden behind galactic dust,” said Martin Still, NSF Program Director for the International Gemini Observatory. “NSF congratulates our Gemini partner, KASI, and the entire telescope staff for achieving the critical milestone of IGRINS-2 first light.”

More information

NSF’s NOIRLab (National Optical-Infrared Astronomy Research Laboratory), 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.



Jennifer Lotz
Director, International Gemini Observatory

Ruben Diaz
Head of Instrumentation, International Gemini Observatory

Hwihyun Kim
Instrumentation Program Scientist, International Gemini Observatory

Josie Fenske
NSF’s NOIRLab Communications

Monday, November 20, 2023

ALMA Demonstrates Highest Resolution Yet

The Band-to-band (B2B) method demonstrated this time to achieve the highest resolution with ALMA. In the B2B method, atmospheric fluctuations are compensated for by observing a nearby calibrator in low frequency radio waves, while the target is observed with high frequency radio waves. The top right inset image shows the ALMA image of R Leporis that achieved the highest resolution of 5 milli-arcsec. Submillimeter-wave emissions from the stellar surface are shown in orange and hydrogen cyanide maser emissions at 891 GHz are shown in blue. The top left inset image shows a previous observation of the same star using a different array configuration with less distance between the antennas and without the B2B method, resulting in a resolution of 75 milli-arcsec. The previous resolution is too coarse to specify the positions of each of the two emission components. (Credit: ALMA (ESO/NAOJ/NRAO), Y. Asaki et al.)
Download image (1.3MB)

ALMA (Atacama Large Millimeter/submillimeter Array) has demonstrated the highest resolution yet with observations of an old star. The observations show that the star is surrounded by a ring-like structure of gas and that gas from the star is escaping to the surrounding space. Future observations with the newly demonstrated high resolution are expected to elucidate, not only the end of a star’s life, but also the beginning, when planets are still forming.

ALMA is a radio interferometric array telescope, in which individual antennas work together to observe a celestial object. ALMA’s resolution, the ability to see small details, is determined by the maximum separation between the antennas and the frequency of the observed radio waves. In this research, an international team comprised mainly of astronomers from the Joint ALMA Observatory, National Astronomical Observatory of Japan (NAOJ), National Radio Astronomy Observatory, and European Southern Observatory used ALMA’s maximum antenna separation of 16 km and highest frequency receivers (known as Band 10, up to 950 GHz) to achieve the best resolution possible. Pushing ALMA’s resolution to new limits also required a new calibration technique to correct for fluctuations in Earth’s atmosphere above the antennas. The calibration technique the team used, known as “band-to-band (B2B),” was originally tested in the 1990s at Nobeyama Radio Observatory of NAOJ for future millimeter/submillimeter interferometers.

For their demonstration observations, the team chose R Leporis, a star in the final stage of stellar evolution, located approximately 1,535 light-years away from Earth. The team succeeded in observing R Leporis with the best resolution ever, 5 milli-arcsec, which is the equivalent of being able to see a single human hair two and a half miles away. The observations show the surface of the star and a ring of gas around the star. The team also confirmed that gas from the star is escaping to the surrounding space.

This newly demonstrated high resolution capability can now be applied to young stars with protoplanetary disks where planets are forming. Future high-resolution observations will provide new insights into how planets, particularly Earth-like planets, form.

Detailed Article(s)

Release Information

Researcher(s) Involved in this Release

Yoshiharu Asaki (Associate Professor @ National Astronomical Observatory of Japan)

Coordinated Release Organization(s)

National Astronomical Observatory of Japan
Joint ALMA Observatory


Yoshiharu. Asaki et al. “ALMA High-frequency Long Baseline Campaign in 2021: Highest Angular Resolution Submillimeter Wave Images for the Carbon-rich Star R Lep”, in The Astrophysical Journal, DOI: 10.3847/1538-4357/acf619

Luke T. Maud et al. “ALMA High-frequency Long-baseline Campaign in 2019: Band 9 and 10 In-band and Band-to-band Observations Using ALMA’s Longest Baselines” in The Astrophysical Journal Supplement Series, DOI: 10.3847/1538-4365/acd6f1

Sunday, November 19, 2023

ALMA Observation of Young Star Reveals Details of Dust Grains

Rings of dust surrounding HL Tauri, with line patterns showing the orientation of polarized light. A new paper published by Stephens, et al., using ALMA, provides the deepest dust polarization image of any protoplanetary disk captured thus far, revealing details about the dust grains in the disk. Credit: NSF/AUI/NRAO/B. Saxton/Stephens et al. Hi-Res File

This gif alternates to show the original observation image with the artists rendering of polarized dust grains. Credit: NSF/AUI/NRAO/B. Saxton/Stephens et al.
Hi-Res File

Highest Resolution Dust Polarization Image Ever Taken Toward a Protoplanetary Disk

One of the primary goals of the Atacama Large Millimeter/submillimeter Array (ALMA) is to study the formation and evolution of planetary systems. Young stars are often surrounded by a disk of gas and dust, out of which planets can form. One of the first high resolution images that ALMA captured was of HL Tauri, a young star just 480 light-years away surrounded by a protoplanetary disk. The disk has visible gaps which could be where young protoplanets are forming. Planetary formation is a complex process that we still don’t fully understand. During this process, dust grains in the disk are growing in size as they collide and stick to each other, causing them to slowly grow to potentially become objects similar to those within our solar system.

One of the ways to study dust grains in these complex structures is to look at the orientation of the light waves they emit, which is known as polarization. Earlier studies of HL Tauri have mapped this polarization, but a new study from Stephens, et al. has captured a polarization image of HL Tauri in unprecedented detail. The resulting image is based on 10x more polarization measurements than of any other disk, and 100x more measurements than most disks. It is by far the deepest polarization image of any disk captured thus far, according to research published today in Nature.

The image was captured at a resolution of 5 AU, which is about the distance from the Sun to Jupiter. Previous polarization observations were at a much lower resolution and didn’t reveal the subtle patterns of polarization within the disk. For example, the team found the amount of polarized light to be greater on one side of the disk than the other, which is likely due to asymmetries in the distribution in the dust grains or their properties across the disk. Dust grains aren’t often spherical. They can be oblate like a thick pancake, or prolate like a grain of rice. When light is emitted by or scatters off these dust grains, it can become polarized, meaning that the waves of light are oriented in a particular direction rather than just randomly. These new results suggest that grains behave more like prolate grains, and they put strong constraints on the shape and size of dust grains within the disk.

A surprising result of the study is that there is more polarization within the gaps of the disk than the rings, even though there is more dust in the rings. The polarization within the gaps is more azimuthal, which suggests the polarization comes from aligned dust grains within the gaps. The polarization of the rings is more uniform, suggesting the polarization largely comes from scattering. In general, the polarization comes from a mix of scattering and dust alignment. Based on the data, it is unclear what is causing the dust grains to align, but they are likely not aligned along the magnetic field of the disk, which is the case for most dust outside of protoplanetary disks. Currently, it is thought that the grains are aligned mechanically, perhaps by their own aerodynamics, as they revolve around the central young star.

What will studies of HL Tau reveal next? This new publication makes clear that high resolution is needed for polarization observations to learn the details about the dust grains. As the world’s most powerful millimeter/ submillimeter telescope, ALMA will be a fundamental instrument for continuing this research.


The Atacama Large Millimeter/submillimeter Array (ALMA), an international astronomy facility, is a partnership of the European Organisation for Astronomical Research in the Southern Hemisphere (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 Ministry of Science and Technology (MOST) 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.

NRAO is a facility of the National Science Foundation, operated under cooperative agreement by Associated Universities, Inc.

Jill Malusky, NRAO & GBO News & Public Information Manager

Scientic Paper

Saturday, November 18, 2023

Same galaxy, different filters

A spiral galaxy. It has several arms that are mixed together and an overall oval shape. The centre of the galaxy glows brightly. There are bright pink patches and filaments of dark red dust spread across the centre. Credit: ESA/Hubble & NASA, R. Chandar, J. Lee and the PHANGS-HST team

This luminous tangle of stars and dust is the barred spiral galaxy NGC 1385, that lies about 30 million light-years from Earth. The same galaxy was the subject of another Hubble Picture of the Week, but the two images are notably different. This more recent image has far more pinkish-red and umber shades, whereas the former image was dominated by cool blues. This chromatic variation is not just a creative choice, but also a technical one, made in order to represent the different number and type of filters used to collect the data that were used to make the respective images.

It is understandable to be a bit confused as to how the same galaxy, imaged twice by the same telescope, could be represented so differently in two different images. The reason is that — like all powerful telescopes used by professional astronomers for scientific research — Hubble is equipped with a range of filters. These highly specialised components have little similarity to filters used on social media: those software-powered filters are added after the image has been taken, and cause information to be lost from the image as certain colours are exaggerated or reduced for aesthetic effect. In contrast, telescope filters are pieces of physical hardware that only allow very specific wavelengths of light to enter the telescope as the data are being collected. This does cause light to be lost, but means that astronomers can probe extremely specific parts of the electromagnetic spectrum. This is very useful for a number of reasons; for example, physical processes within certain elements emit light at very specific wavelengths, and filters can be optimised to these wavelengths.

Take a look at this week's image and the earlier image of NGC 1385. What are the differences? Can you see the extra detail (due to extra filters being used) in this week’s image?

Friday, November 17, 2023

Rapid Increase in Oxygen in Early Universe

JWST infrared images of 6 galaxies from 500-700 million years after the birth of the Universe. All 6 have low oxygen abundances compared to modern galaxies. (Credit: NASA, ESA, CSA, K. Nakajima et al.)
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Using new data from the James Webb Space Telescope, astronomers have measured the abundance of oxygen in the early Universe. The findings show that the amount of oxygen in galaxies increased rapidly within 500-700 million years after the birth of the Universe, and has remained as abundant as observed in modern galaxies since then. This early appearance of oxygen indicates that the elements necessary for life were present earlier than expected.

In the early Universe, shortly after the Big Bang, only light elements such as hydrogen, helium, and lithium existed. Heavier elements like oxygen were subsequently formed through nuclear fusion reactions within stars and dispersed into galaxies, primarily through events like supernova explosions. This ongoing process of element synthesis, unfolding over the vast expanse of cosmic history, created the diverse elements that constitute the world and living organisms around us.

A research team led by Kimihiko Nakajima at the National Astronomical Observatory of Japan used data from the James Webb Space Telescope (JWST) to measure the oxygen in 138 galaxies that existed in the first 2 billion years of the Universe. The team found that most of the galaxies had oxygen abundances similar to modern galaxies. But out of the 7 earliest galaxies in the sample, those that existed when the Universe was only 500-700 million years old, 6 of them had roughly half the predicted oxygen content.

This rapid increase in oxygen content occurred earlier than astronomers were expecting. This opens the possibility that with the necessary ingredients, like oxygen, already readily available in the early Universe that life may have appeared sooner than previously thought.

Detailed Article(s)

Rapid Increase in Oxygen in Early Universe


Release Information

Researcher(s) Involved in this Release

Kimihiko Nakajima (Project Assistant Professor @ National Astronomical Observatory of Japan)
Masami Ouchi (Professor @ National Astronomical Observatory of Japan, Professor @ Institute for Cosmic Ray Research, The University of Tokyo)
Yuichi Harikane (Assistant Professor @ Institute for Cosmic Ray Research, The University of Tokyo)
Yoshiaki Ono (Assistant Professor @ Institute for Cosmic Ray Research, The University of Tokyo)
Yuki Isobe (Doctoral Student @ Graduate School of Science, Tohoku University)
Hiroya Umeda (Doctoral Student @ Graduate School of Science, Tohoku University)
Masamune Oguri (Professor @ Center for Frontier Science, Chiba University)
Yechi Zhang (JSPS Postdoctoral Fellow @ National Astronomical Observatory of Japan)

Coordinated Release Organization(s)

National Astronomical Observatory of Japan
The University of Tokyo


Kimihiko Nakajima et al. “JWST Census for the Mass-Metallicity Star Formation Relations at z = 4-10 with Self-consistent Flux Calibration and Proper Metallicity Calibrators”, in The Astrophysical Journal Supplement Series,
DOI: 10.3847/1538-4365/acd556

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