Astronomers release most complete ultraviolet-light survey of nearby galaxiesMay 17, 2018
Capitalizing on the unparalleled sharpness and spectral range of NASA's Hubble Space Telescope, an international team of astronomers is releasing the most comprehensive, high-resolution ultraviolet-light survey of nearby star-forming galaxies.
The researchers combined new Hubble observations with archival Hubble images for 50 star-forming spiral and dwarf galaxies in the local universe, offering a large and extensive resource for understanding the complexities of star formation and galaxy evolution. The project, called the Legacy ExtraGalactic UV Survey (LEGUS), has amassed star catalogs for each of the LEGUS galaxies and cluster catalogs for 30 of the galaxies, as well as images of the galaxies themselves. The data provide detailed information on young, massive stars and star clusters, and how their environment affects their development.
"There has never before been a star cluster and a stellar catalog that included observations in ultraviolet light," explained survey leader Daniela Calzetti of the University of Massachusetts, Amherst. "Ultraviolet light is a major tracer of the youngest and hottest star populations, which astronomers need to derive the ages of stars and get a complete stellar history. The synergy of the two catalogs combined offers an unprecedented potential for understanding star formation."
How stars form is still a vexing question in astronomy. "Much of the light we get from the universe comes from stars, and yet we still don't understand many aspects of how stars form," said team member Elena Sabbi of the Space Telescope Science Institute in Baltimore, Maryland. "This is even key to our existence -- we know life wouldn't be here if we didn't have a star around."
The research team carefully selected the LEGUS targets from among 500 galaxies, compiled in ground-based surveys, located between 11 million and 58 million light-years from Earth. Team members chose the galaxies based on their mass, star-formation rate, and abundances of elements that are heavier than hydrogen and helium. The catalog of ultraviolet objects collected by NASA's Galaxy Evolution Explorer (GALEX) spacecraft also helped lay the path for the Hubble study.
The team used Hubble's Wide Field Camera 3 and the Advanced Camera for Surveys over a one-year period to snap visible- and ultraviolet-light images of the galaxies and their most massive young stars and star clusters. The researchers also added archival visible-light images to provide a complete picture.
The star cluster catalogs contain about 8,000 young clusters whose ages range from 1 million to roughly 500 million years old. These stellar groupings are as much as 10 times more massive than the largest clusters seen in our Milky Way galaxy.
The star catalogs comprise about 39 million stars that are at least five times more massive than our Sun. Stars in the visible-light images are between 1 million and several billion years old; the youngest stars, those between 1 million and 100 million years old, shine prominently in ultraviolet light.
The Hubble data provide all of the information to analyze these galaxies, the researchers explained. "We also are offering computer models to help astronomers interpret the data in the star and cluster catalogs," Sabbi said. "Researchers, for example, can investigate how star formation occurred in one specific galaxy or a set of galaxies. They can correlate the properties of the galaxies with their star formation. They can derive the star-formation history of the galaxies. The ultraviolet-light images may also help astronomers identify the progenitor stars of supernovas found in the data."
One of the key questions the survey may help astronomers answer is the connection between star formation and the major structures, such as spiral arms, that make up a galaxy.
"When we look at a spiral galaxy, we usually don't just see a random distribution of stars," Calzetti said. "It's a very orderly structure, whether it's spiral arms or rings, and that's particularly true with the youngest stellar populations. On the other hand, there are multiple competing theories to connect the individual stars in individual star clusters to these ordered structures.
"By seeing galaxies in very fine detail -- the star clusters -- while also showing the connection to the larger structures, we are trying to identify the physical parameters underlying this ordering of stellar populations within galaxies. Getting the final link between gas and star formation is key for understanding galaxy evolution."
Team member Linda Smith of the European Space Agency (ESA) and the Space Telescope Science Institute added: "We're looking at the effects of the environment, particularly with star clusters, and how their survival is linked to the environment around them."
The LEGUS survey will also help astronomers interpret views of galaxies in the distant universe, where the ultraviolet glow from young stars is stretched to infrared wavelengths due to the expansion of space. "The data in the star and cluster catalogs of these nearby galaxies will help pave the way for what we see with NASA's upcoming infrared observatory, the James Webb Space Telescope, developed in partnership with ESA and the Canadian Space Agency (CSA)," Sabbi said.
Webb observations would be complementary to the LEGUS views. The space observatory will penetrate dusty stellar cocoons to reveal the infrared glow of infant stars, which cannot be seen in visible- and ultraviolet-light images. "Webb will be able to see how star formation propagates over a galaxy," Sabbi continued. "If you have information on the gas properties, you can really connect the points and see where, when, and how star formation happens."
For more information about LEGUS and Hubble, visit:
Donna Weaver / Ray Villard
Space Telescope Science Institute, Baltimore, Maryland
410-338-4493 / 410-338-4514
firstname.lastname@example.org / email@example.com
NASA's Goddard Space Flight Center, Greenbelt, Maryland
NASA/Goddard Space Flight Center
Related Hubble Space Telescope Articles:
For the first time, astronomers have used a novel method to determine the mass of a type of star known as a 'white dwarf' -- the shrunken corpse of a dead star that used to be like our sun.
At NASA's Goddard Space Flight Center in Greenbelt, Maryland the James Webb Space Telescope team completed the acoustic and vibration portions of environmental testing on the telescope.
With the discovery of seven earth-sized planets around the TRAPPIST-1 star 40 light years away, astronomers are looking to the upcoming James Webb Space Telescope to help us find out if any of these planets could possibly support life.
Testing on the James Webb Space Telescope successfully resumed last week at NASA's Goddard Space Flight Center, in Greenbelt, Md.
A new concept in space telescope design uses a modular structure and an assembly robot to build an extremely large telescope in space, performing tasks in which astronaut fatigue would be a problem.
With surgical precision, two dozen engineers and technicians successfully installed the package of science instruments of the James Webb Space Telescope into the telescope structure.
NASA engineers recently unveiled the giant golden mirror of NASA's James Webb Space Telescope as part of the integration and testing of the infrared telescope.
Combining an orbiting radio telescope with telescopes on Earth made a system capable of the highest resolution of any observation ever made in astronomy.
NASA's James Webb Space Telescope just got a little closer to launch with the completion of cryogenic testing on its science cameras and spectrographs and the installation of the final flight mirrors.
The sole secondary mirror that will fly aboard NASA's James Webb Space Telescope was installed onto the telescope at NASA's Goddard Space Flight Center in Greenbelt, Maryland, on March 3, 2016.
Related Hubble Space Telescope Reading:
The Hubble Cosmos: 25 Years of New Vistas in Space
by David H. Devorkin (Author), Robert W. Smith (Author), Robert P. Kirshner (Foreword)
To celebrate NASA’s Hubble Space Telescope and its 25 years of accomplishments, let The Hubble Cosmos fill your mind with big ideas, brilliant imagery, and a new understanding of the universe in which we live. Relive key moments in the monumental Hubble story, from launch through major new instrumentation to the promise of discoveries to come. With more than 150 photographs including Hubble All-Stars—the most famous of all the noteworthy images—The Hubble Cosmos shows how this telescope is revolutionizing our understanding of the universe. View Details
Hubble's Universe: Greatest Discoveries and Latest Images
by Terence Dickinson (Author)
Praise for the first edition:
"Superbly well produced. Any engagement with this 'cosmic portfolio,' from picture gazing to deep reading, is grandly rewarded."
[starred review] "The book's precise descriptions and captions brilliantly complement the 300 full-color Hubble images . . . this is an amazing book . . . outstanding."
"A treasure map to the majesty of our universe."
"A reminder that the finest telescope in space might also be the greatest camera ever... View Details
NASA Hubble Space Telescope - 1990 onwards (including all upgrades): An insight into the history, development, collaboration, construction and role of space telescope (Owners' Workshop Manual)
by David Baker (Author)
The Hubble Space Telescope is an international venture primarily between the USA and Europe. More than any other space project, Hubble has encouraged an expanding interest in popular astronomy. With stunning views of the cosmos, it has inspired a new generation of enthusiasts to study the night sky through simple telescopes or in books. As such it has linked space technology with popular interest in astronomy and has thrilled specialists and the lay public alike.View Details
Hubble Space Telescope: Photographing the Universe (Xtreme Spacecraft)
by John Hamilton (Author)
Simple text and "out-of-this-world" photography introduce readers to NASA's Hubble Space Telescope, and its mission to photograph the wonders of the universe, far above the atmosphere of Earth. Important details covered include the space observatory's planning and engineering, its launch, its scientific discoveries, and how its images have changed our perception of the cosmos. Aligned to Common Core Standards and correlated to state standards. A&D Xtreme is an imprint of Abdo Publishing, a division of ABDO. View Details
Hubble Space Telescope 2019 12 x 12 Inch Monthly Square Wall Calendar by Wyman, Science Space Technology
by Inc. BrownTrout Publishers (Author), BrownTrout Publishers Editing Team (Editor), BrownTrout Publishers Design Team (Editor)
Hubble Space Telescope 2019 12 x 12 Inch Monthly Square Wall Calendar by Wyman, Science Space Technology View Details
Expanding Universe: Photographs from the Hubble Space Telescope
by Owen Edwards (Contributor), Zoltan Levay (Contributor)
Time, space, and a telescope: Hubble’s most magnificent images
With investigations into everything from black holes to exoplanets, the Hubble Telescope has changed not only the face of astronomy, but also our very sense of being in the universe. On the 25th anniversary of its launch into low-earth orbit, TASCHEN celebrates its most breathtaking deep space images both as scientific feats and as photographic masterpieces.
Ultra high-resolution and taken with almost no background... View Details
Hubble Space Telescope: New Views of the Universe
by Mark Voit (Author)
Colorful and awe-inspiring poster-size photographs of emerging star, nebulae, and other astronomical marvels highlight an exploration of the impact that the Hubble Space Telescope has had on scientific study and general appreciation of the wonders of the skies. Original. View Details
The Hubble Space Telescope (Space Tech)
by Blake Hoena (Author)
The Hubble Space Telescope is a lens for discovering the hidden secrets of outer space. The tool has zoomed in on unknown galaxies! This book gives young readers a close-up of the Hubble Space Telescope, showing off its mirrors, cameras, solar panels, and more.View Details
The Hubble Space Telescope: From Concept to Success (Springer Praxis Books)
by David J. Shayler (Author), David M. Harland (Author)
The highly successful Hubble Space Telescope was meant to change our view and understanding of the universe. Within weeks of its launch in 1990, however, the space community was shocked to find out that the primary mirror of the telescope was flawed. It was only the skills of scientists and engineers on the ground and the daring talents of astronauts sent to service the telescope in December 1993 that saved the mission.
For over two decades NASA had developed the capabilities to service a payload in orbit. This involved numerous studies and the creation of a ground-based... View Details
Hubble: Imaging Space and Time
by David H. Devorkin (Author), Robert Smith (Author)
In the spirit of National Geographic’s top-selling Orbit, this large-format, full-color volume stands alone in revealing more than 200 of the most spectacular images from the Hubble Space Telescope during its lifetime, to the very eve of the 2008 final shuttle mission to the telescope. Written by two of the world’s foremost authorities on space history, Hubble: Imaging Space and Time illuminates the solar system’s workings, the expansion of the universe, the birth and death of stars, the formation of planetary nebulae, the dynamics of galaxies, and the mysterious force... View Details