Hayadan > Astronomers have prepared the most comprehensive survey of nearby galaxies in the ultraviolet field with the help of Hubble

Astronomers have prepared the most comprehensive survey of nearby galaxies in the ultraviolet field with the help of Hubble

The researchers combined new Hubble observations with an image of archaeology, and studied fifty spiral galaxies and dwarf galaxies where many stars form in our local neighborhood of the universe. The project known as the Legacy ExtraGalactic UV Survey (LEGUS) contains a star catalog for each of the galaxies and a star cluster catalog for 30 of the galaxies, as well as images of the galaxies themselves

These six images represent the variety of star-forming regions in nearby galaxies. The galaxies are part of the Hubble Space Telescope's Legacy ExtraGalactic UV Survey (LEGUS). This is the largest and most comprehensive survey of ultraviolet (UV) light observations of star-forming galaxies in the near Universe. the neighbor The six images include two dwarf galaxies (UGC 5340 and UGCA 281) and four large spiral galaxies (NGC 3368, NGC 3627, NGC 6744 and NGC 4258). The images are a mixture of ultraviolet and visible light from Hubble's Wide Field Camera No. 3 and its Advanced Survey Camera. CREDIT: NASA/ESA/LEGUS TEAM

Astronomers using the power and spectral range of the Hubble Space Telescope have released the most comprehensive, high-resolution survey of star-forming galaxies in the near universe in ultraviolet light.

"Until now, a comprehensive catalog of star clusters and stars that includes observations in the ultraviolet field has never been prepared," explains the leader of the survey, Daniela Calzetti from the University of Massachusetts in Amherst. "Ultraviolet light is a means of tracking the populations of young, hot stars, from which astronomers can deduce the age of the stars and reconstruct their complete stellar history. The synergy between two catalogs put together provides unprecedented potential for understanding the process of star formation."

The question of how stars are born is still an open question in astronomy. "Most of the light we receive from the universe comes from stars, yet we still do not understand many aspects of their formation process," said team member Elena Sabi of the Space Telescope Science Institute in Baltimore, Maryland. "The stars are the key to our existence - we know that life would not have formed here if there were no stars."

The research team carefully selected the LEGUS targets from 500 galaxies, collected in ground-based surveys, located at distances of 11-5 and 8 million light-years from Earth. Team members selected galaxies based on their mass, star formation rate, and abundance of elements heavier than hydrogen and helium. The catalog of objects in the ultraviolet light range photographed by NASA's GALEX spacecraft also helped pave the way for Hubble research.

Team members used Hubble's Wide Field Camera 3 and the Advanced Camera for Surveys for one year to take visible and ultraviolet images of the galaxies and their youngest and most massive stars. The researchers also added archival images of those galaxies in visible light to provide a complete picture.

The star cluster catalogs contain about 8,000 young star clusters whose age ranges from 500 million to 10 million years. These star clusters are XNUMX times more massive than the largest clusters in our Milky Way galaxy.

The star catalog contains about 39 million stars that are at least five times more massive than our sun. The stars in the visible light photographs are between a million and a billion years old; The youngest stars, between one million and 100 million years old, shine with ultraviolet light.

The Hubble data provide all the information needed to analyze these galaxies, the researchers explained. "We also offer computer models that can help astronomers interpret the data in the catalogs of B stars and star clusters," Sabi said. "Researchers, for example, can study how stars were formed in a particular galaxy or a cluster of galaxies, and they can link the properties of galaxies with the nature of their star formation, and derive the history of the galaxy. Visible light images may help astronomers identify ancient supernovae found in the data."

One of the key questions that the survey may help astronomers answer is the relationship between star formation and the main 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 ordered structure, whether it's spiral arms or rings, and that's especially true for the youngest star populations. On the other hand, there are many competing theories to connect the individual stars in the individual clusters to these ordered structures.

"When we see galaxies in very fine detail, down to the level of star clusters, while showing the relationship to the larger structures, we try to identify the physical parameters that underlie this arrangement of star populations within galaxies. The goal is also to understand the relationship between the mass of stars and the mass of interstellar gas as a key to understanding the evolution of galaxies."

Team member Linda Smith of the European Space Agency (ESA) and the Space Telescope Science Institute in Maryland added that "we are testing the effects of the environment on star clusters."

The LEGUS survey will also help astronomers interpret observations of galaxies in the distant universe, where ultraviolet glow from young stars is stretched to infrared wavelengths due to the expansion of the universe. "The data in the catalog of stars and clusters in these nearby galaxies will help pave the way to understanding what we see at NASA's upcoming infrared observatory, the James Webb Space Telescope, which is being developed in collaboration with the European Space Agency and the Canadian Space Agency," Sabi said. .

The Webb observations will be the anchor for the LEGUS observations. The new space telescope will penetrate the dusty interstellar depths to reveal the infrared glow of newborn stars that cannot be seen in visible and ultraviolet light. "Webb will be able to see how the process of star formation spreads throughout the galaxy," Sabi continued. "If you have information about the properties of the gas, you can really connect the dots and see where, when and how a star was born."

to the announcement of the European Space Agency

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