Signs of the stellar lifecycle Signs of the stellar lifecycle

NGC 1637

A spiral galaxy filling the view. Its disc is filled with bright red spots where stars are forming, dark reddish threads of dust that obscure light, and bluish glowing areas where older stars are concentrated. It has a large, glowing yellow oval area at the centre, from which two spiral arms wind through the galaxy’s disc. The bottom side of the disc is rounded while the top side is somewhat squared-off. Credit: ESA/Hubble & NASA, D. Thilker

The subject of this NASA/ESA Hubble Space Telescope Picture of the Week is NGC 1637, a spiral galaxy located 38 million light-years from Earth in the constellation Eridanus.

This image comes from an observing programme dedicated to studying star formation in nearby galaxies. Stars form in cold, dusty gas clouds that collapse under their own gravity. As young stars grow, they heat their nurseries through starlight, winds, and powerful outflows. Together, these factors play a role in controlling the rate at which future generations of stars form.

Evidence of star formation is scattered all around NGC 1637, if you know where to look. The galaxy’s spiral arms are dotted with what appear to be pink clouds, many of which are accompanied by bright blue stars. The pinkish colour comes from hydrogen atoms that have been excited by ultraviolet light from young, massive stars. This contrasts with the warm yellow glow of the galaxy’s centre, which is home to a densely packed collection of older, redder stars.

The stars that set their birthplaces aglow are comparatively short-lived, and many of these stars will explode as supernovae just a few million years after they’re born. In 1999, NGC 1637 played host to a supernova, pithily named SN 1999emsupe, that was lauded as the brightest supernova seen that year. When a massive star expires as a supernova, the explosion outshines its entire home galaxy for a short time. While a supernova marks the end of a star’s life, it can also jump start the formation of new stars by compressing nearby clouds of gas, beginning the stellar lifecycle anew.

Source: ESA/Hubble/potw.

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A galactic rejuvenation

Astronomers observing the galaxy NGC 1386, located 53 million light-years away, have discovered a unique pattern of star formation. Using data from the VLT Survey Telescope, ALMA, and other instruments, they found a central blue ring filled with young stars that all formed nearly simultaneously 4 million years ago—a rare synchronized event for a galaxy with mostly older stars. Also, ALMA data revealed gas clouds forming a golden ring, suggesting a new wave of star formation may begin in about 5 million years. Credit: ESO/ALMA (ESO/NAOJ/NRAO)/A. Prieto et al./Fornax Deep Survey. Crdit: ESO/ALMA (ESO/NAOJ/NRAO)/A. Prieto et al./Fornax Deep Survey

Something odd is happening in NGC 1386, a spiral galaxy located 53 million light-years away in Eridanus's constellation. This Picture combines data from the Atacama Large Millimetre/Submillimetre Array (ALMA) and the VLT Survey Telescope (VST), hosted at ESO’s Paranal Observatory in Chile. When astronomers observed the central regions of this galaxy, they found new stars forming… albeit in a peculiar way.

Stars often form within stellar clusters – groups of thousands of stars that originate from massive clouds of molecular gas. The blue ring at the center of this galaxy is ripe with stellar clusters full of young stars, as seen by VST. A new study led by Almudena Prieto, an astronomer at the Instituto de Astrofísica de Canarias in Spain, used data from ESO’s Very Large Telescope (VLT) and the NASA/ESA Hubble Space Telescope to look at this ring in more detail. The data shows that all these star clusters formed almost simultaneously 4 million years ago. It is the first time synchronized star formation has been observed in a galaxy mainly containing old stars.

The same study used ALMA to reveal even more secrets in this galaxy. Shown in this picture as a golden ring is a multitude of gas clouds, ready to form a second batch of young stars. However, we will still have to wait 5 million years for these to be born. Even if old, NGC 1386 keeps rejuvenating itself.

Scienfic Paper

Source: ALMA (Atacama Large Millimeter/submillimeter Array)/News

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Additional Information

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 US 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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Contacts:

Nicolás Lira
Education and Public Outreach Coordinator
Joint ALMA Observatory, Santiago - Chile
Phone: +56 2 2467 6519
Cel: +56 9 9445 7726
Email: nicolas.lira@alma.cl

Juan Carlos Muñoz Mateos
ESO Media Officer
Garching bei München, Germany
Phone: +49 89 3200 6176
Email: press@eso.org

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A supernova spotlight

LEDA 857074

A close-in view of a barred spiral galaxy. The bright, glowing bar crosses the centre of the galaxy, with blurred spiral arms curving away from its ends and continuing out of view. It’s surrounded by bright points of light that indicate stars and galaxies. The galaxy also hosts a bright supernova in its central bar.Credit: ESA/Hubble & NASA, R. J. Foley

This Hubble Picture of the Week features the galaxy LEDA 857074, located in the constellation Eridanus. LEDA 857074 is a barred spiral galaxy, with partially broken spiral arms. It also has a particularly bright spot right in its bar: this is a supernova snapped by Hubble, named SN 2022ADQZ, and quite relevant to this Picture of the Week.

The NASA/ESA Hubble Space Telescope has observed a vast range of celestial objects, from galaxies, to nebulae, to star clusters, to planets in the Solar System and beyond. Observing programmes usually seek to gather data so that astronomers can answer a specific question. Naturally, this means most scheduled observations target an object that astronomers have already researched. Some are famous, like the Crab Nebula or the globular cluster Omega Centauri; others might not be so well known to the public, but still be featured in hundreds of scientific papers, such as the Spider Galaxy or NGC 4753. Not so with this galaxy: LEDA 857074 is named in fewer than five papers, one of which is the Lyon-Meudon Extragalactic Database itself. Virtually no data have been recorded about it, other than its position: since its discovery, it simply hasn’t been studied. So how did it attract the gaze of the legendary Hubble?

The supernova is the answer — SN 2022ADQZ was detected by an automated survey in late 2022, and led to Hubble being pointed at its host galaxy, LEDA 857074, in early 2023. Astronomers have catalogued millions of galaxies, so while today tens of thousands of supernovae are detected annually, the chance that one is spotted in any particular galaxy is slim. We also do not know how actively LEDA 857074 is forming stars, and therefore how often it might host a supernova. This galaxy is therefore an unlikely and lucky target of Hubble, thanks to this supernova shining a spotlight on it! It now joins the ranks of many more famous celestial objects, with its own Hubble image.

Source: ESA/Hubble/potw

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A Cold Cosmic Mystery Solved: Astronomers discover what might be the largest known structure in the universe that leaves its imprint on cosmic microwave background radiation

The Cold Spot area resides in the constellation Eridanus in the southern galactic hemisphere. The insets show the environment of this anomalous patch of the sky as mapped by Szapudi’s team using PS1 and WISE data and as observed in the cosmic microwave background temperature data taken by the Planck satellite. The angular diameter of the vast supervoid aligned with the Cold Spot, which exceeds 30 degrees, is marked by the white circles. Graphics by Gergő Kránicz. Image credit: ESA Planck Collaboration. High-resolution version (6.6 Mb)

Synopsis: A very large cold spot that has been a mystery for over a decade can now be explained

In 2004, astronomers examining a map of the radiation leftover from the Big Bang (the cosmic microwave background, or CMB) discovered the Cold Spot, a larger-than-expected unusually cold area of the sky. The physics surrounding the Big Bang theory predicts warmer and cooler spots of various sizes in the infant universe, but a spot this large and this cold was unexpected.

Now, a team of astronomers led by Dr. István Szapudi of the Institute for Astronomy at the University of Hawaii at Manoa may have found an explanation for the existence of the Cold Spot, which Szapudi says may be “the largest individual structure ever identified by humanity.” 

If the Cold Spot originated from the Big Bang itself, it could be a rare sign of exotic physics that the standard cosmology (basically, the Big Bang theory and related physics) does not explain. If, however, it is caused by a foreground structure between us and the CMB, it would be a sign that there is an extremely rare large-scale structure in the mass distribution of the universe. 

Using data from Hawaii’s Pan-STARRS1 (PS1) telescope located on Haleakala, Maui, and NASA’s Wide Field Survey Explorer (WISE) satellite, Szapudi’s team discovered a large supervoid, a vast region 1.8 billion light-years across, in which the density of galaxies is much lower than usual in the known universe. This void was found by combining observations taken by PS1 at optical wavelengths with observations taken by WISE at infrared wavelengths to estimate the distance to and position of each galaxy in that part of the sky.

Earlier studies, also done in Hawaii, observed a much smaller area in the direction of the Cold Spot, but they could establish only that no very distant structure is in that part of the sky. Paradoxically, identifying nearby large structures is harder than finding distant ones, since we must map larger portions of the sky to see the closer structures. The large three-dimensional sky maps created from PS1 and WISE by Dr. András Kovács (Eötvös Loránd University, Budapest, Hungary) were thus essential for this study. The supervoid is only about 3 billion light-years away from us, a relatively short distance in the cosmic scheme of things.

Imagine there is a huge void with very little matter between you (the observer) and the CMB. Now think of the void as a hill. As the light enters the void, it must climb this hill. If the universe were not undergoing accelerating expansion, then the void would not evolve significantly, and light would descend the hill and regain the energy it lost as it exits the void. But with the accelerating expansion, the hill is measurably stretched as the light is traveling over it. By the time the light descends the hill, the hill has gotten flatter than when the light entered, so the light cannot pick up all the energy it lost upon entering the void. The light exits the void with less energy, and therefore at a longer wavelength, which corresponds to a colder temperature.

Getting through a supervoid can take millions of years, even at the speed of light, so this measurable effect, known as the Integrated Sachs-Wolfe (ISW) effect, might provide the first explanation one of the most significant anomalies found to date in the CMB, first by a NASA satellite called the Wilkinson Microwave Anisotropy Probe (WMAP), and more recently, by Planck, a satellite launched by the European Space Agency.

While the existence of the supervoid and its expected effect on the CMB do not fully explain the Cold Spot, it is very unlikely that the supervoid and the Cold Spot at the same location are a coincidence. The team will continue its work using improved data from PS1 and from the Dark Energy Survey being conducted with a telescope in Chile to study the Cold Spot and supervoid, as well as another large void located near the constellation Draco. 

The study is being published online on April 20 in Monthly Notices of the Royal Astronomical Society by the Oxford University Press. In addition to Szapudi and Kovács, researchers who contributed to this study include UH Manoa alumnus Benjamin Granett (now at the National Institute for Astrophysics, Italy), Zsolt Frei (Eötvös Loránd), and Joseph Silk (Johns Hopkins).

Contacts:

Dr. István Szapudi
+1 808 956-6196
szapudi@ifa.hawaii.edu
 
Dr. András Kovács
+34 93 176 3966
akovacs@ifae.es

Dr. Roy Gal
+1 808-956-6235
cell: +1 301-728-8637
rgal@ifa.hawaii.edu

Ms. Louise Good
Media Contact
+1 808-381-2939
good@ifa.hawaii.edu

 Source:  Institute for Astronomy - University of Hawaii 

Note:

Founded in 1967, the Institute for Astronomy at the University of Hawaii at Manoa conducts research into galaxies, cosmology, stars, planets, and the sun. Its faculty and staff are also involved in astronomy education, deep space missions, and in the development and management of the observatories on Haleakala and Maunakea. The Institute operates facilities on the islands of Oahu, Maui, and Hawaii.

The Pan-STARRS1 Surveys (PS1) have been made possible through contributions by the Institute for Astronomy, the University of Hawaii, the Pan-STARRS Project Office, the Max-Planck Society and its participating institutes, the Max Planck Institute for Astronomy, Heidelberg and the Max Planck Institute for Extraterrestrial Physics, Garching, The Johns Hopkins University, Durham University, the University of Edinburgh, the Queen's University Belfast, the Harvard-Smithsonian Center for Astrophysics, the Las Cumbres Observatory Global Telescope Network Incorporated, the National Central University of Taiwan, the Space Telescope Science Institute, and the National Aeronautics and Space Administration under Grant No. NNX08AR22G issued through the Planetary Science Division of the NASA Science Mission Directorate, the National Science Foundation Grant No. AST-1238877, the University of Maryland, Eötvös Loránd University (ELTE), and the Los Alamos National Laboratory.