Millions of Spectra Reveal the Hidden Lives of Stellar Nurseries
The Sloan Digital Sky Survey’s Local Volume Mapper is providing an unprecedented spectroscopic view of stellar nurseries in the Milky Way. Its first public observations, now released as part of SDSS-V Data Release 20, contain about 300,000 spectra of six objects, including the Trifid and Rosette Nebulae. Heidelberg scientists used these data to reveal how radiation and winds from massive stars shape the temperature, density and chemical composition of surrounding gas. (Heidelberg, August 3, 2026)
Our Milky Way galaxy is a dynamic place, where stars are born, live their lives, and die. Of particular interest is understanding how stars shape the gas and dust around them, blowing hot bubbles that glow in a multitude of different colors. These bubbles are not usually seen in distant galaxies simply because they are too small, but understanding how they form and change over time is critical to understanding how galaxies themselves form and change over time. To achieve these goals, the Sloan Digital Sky Survey (SDSS-V) makes measurements of light at thousands of different colors (‘spectra’) all at once and now with one new telescope within the SDSS-V portfolio - the Local Volume Mapper (LVM).
LVM: SDSS' new working horse
The LVM has been operating since 2023 at the Las Campanas Observatory, in the Atacama desert of Chile. It is designed to specifically survey large areas of the sky, with a telescope field of view that is so large it can image an area of sky of the size of the moon in one shot. Its spectrograph, called an Integral Field Unit (IFU), is able to capture light at over 10.000 colors simultaneously and allows scientists to study star formation, bubbles, shocks, turbulence, and ionized gas flows in the Milky Way at physical scales unreachable in distant galaxies.
This unique approach enables scientists to study sites where young, massive stars are still embedded in the clouds of gas where they were born. In these locations, the photons from these massive stars have so much energy that they excite the gas and cause it to glow. This glowing tells us about the elements present, for example how much oxygen, nitrogen and sulphur is there. But truely understanding the signatures of these different elements requires careful modeling the temperature and density of the gas.
Prominent proxies - Trifid and Rosette
Many of these striking nebulae are well known objects, with memorable names. Two of these, the Trifid Nebula and the Rosette Nebula, have been the subject of recent studies led by PhD students in the SDSS-V/LVM collaboration. The Trifid Nebula is powered by energy and photons from a single massive star, and shows a very simple structure in temperature, well described by models. On the other hand, the Rosette Nebula is powered by a larger cluster of stars, and is dynamically interacting with its surrounding dense molecular gas, creating a much more complicated structure. “In the Trifid Nebula, the density varies significantly as a result of the interaction between stellar radiation and the surrounding molecular gas,” observed Natascha Sattler, PhD student at the Centre for Astrononomy of Heidelberg University (ZAH) and lead author on the paper. “Despite these pronounced density fluctuations, the temperature remains emarkably uniform across our two-dimensional view of the nebula. This simple thermal structure makes the Trifid Nebula an ideal laboratory for studying the chemical composition of star-forming regions.” The Rosette Nebula, studied by Monica Villa-Durango, PhD student at the Universidad Nacional Autónoma de México (UNAM), tell a different story and taken together, these studies demonstrate that unlike simple regions, complex star-forming regions may be misunderstood in distant galaxies, where the internal structure cannot be directly mapped.
The observations that made this work possible have now being made publicy available. This includes the Trifid and Rosette Nebulae, along with 2 other Galactic nebulae (the Orion and Helix nebulae) and 2 nearby galaxies. “Together the release includes 300,000 spectra, but this is only 1% of what LVM has already observed,” said Oleg Egorov, researcher at ZAH, who led quality control for the LVM data. “These are not just pretty pictures of nebulae — they are fingerprints of glowing gas that let us read temperature, density, and chemistry, and see how newborn stars sculpt the Milky Way.” At completion the survey aims to collect over 55 million spectra. “These observations showcase the remarkable breadth and depth of LVM,” added Kathryn Kreckel, group leader at ZAH and survey scientist for the LVM project, “revealing thecomplex ecosystems of gas and stars in exquisite detail. With millions more spectra still to be collected, we are only beginning to explore the scientific opportunities this survey will provide.”
Open Data Access
SDSS-V is committed to the principle of open data access, and the data release also includes computer code repositories to demonstrate how the data products can be used freely by scientists all over the world. New LVM data can be explored within the web-based LVMvis, an interactive data interface where citizens and scientists can explore measurements and spectroscopy across nebulae and galaxies.
ABOUT the Sloan Digital Sky Survey (SDSS)
The SDSS-V collaboration is made up of hundreds of scientists from over 70 institutes in 13 different countries, and this is the 20th time that the SDSS collaboration has made a public data release. The first official data release was in 2003, over 20 years ago. The current data release, called DR20, also contains new data from two other SDSS-V surveys, the Milky Way Mapper (MWM) and the Black Hole Mapper (BHM). Together the 3 mapper projects are used by scientists to understand the life cycles of stars and galaxies and determine how matter and energy are distributed throughout the universe, from individual stars up to supermassive black holes in distant galaxies. This is only the beginning of discoveries with LVM, which will ultimately survey hundreds of nebulae in our own galaxy. These observations provide the missing, highly-resolved view ofhow stars sculpt bubbles into the surrounding gas, a key missing piece in understanding how galaxies grow and evolve across cosmic time.
RELATED PRESS RELEASE
https://www.sdss.org/sdss-launches-twentieth-release/
SDSS DR20 DATA ACCESS
https://www.sdss.org/dr20/
ORIGINAL PUBLICATIONS
SDSS-V LVM: Resolving physical conditions in the Trifid Nebula
SDSS-V Local Volume Mapper (LVM): revealing the structure of the Rosette Nebula
SDSS-V Local Volume Mapper (LVM): A glimpse into Orion
ABOUT ZAH
The Centre for Astronomy of Heidelberg University (ZAH) brings together Heidelberg’s major university astronomy institutes and research groups across observational, theoretical, and computational astrophysics. Research at ZAH spans topics from exoplanets and nearby stars to the Milky Way, external galaxies, cosmology, instrumentation, and scientific computing.
SCIENTIFIC CONTACT
Dr. Kathryn Kreckel
Centre for Astronomy of Heidelberg University (ZAH)
Astronomisches Rechen-Institut (ARI)
Email: kreckel(at)uni-heidelberg.de
Web: wwwstaff.ari.uni-heidelberg.de/kkreckel/
Natascha Sattler
Centre for Astronomy of Heidelberg University (ZAH)
Astronomisches Rechen-Institut (ARI)
Email: N.Sattler(at)stud.uni-heidelberg.de
Web: https://nataschasattler.github.io/
CONTACT FOR MEDIA INQUIRIES
Dr. Guido Thimm
Centre for Astronomy of Heidelberg University (ZAH)
Email: thimm@uni-heidelberg.de
