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Study Detects Previously Unseen Tracers of Massive Star Formation in the Milky Way

Astronomers conducted an elaborate and sensitive survey of a large portion of the Milky Way galaxy using two of the world’s most powerful radio telescopes. They were able to detect previously unseen tracers of huge star formation, a process that controls galactic ecosystems.

GLOSTAR image, using data from both the VLA and the Effelsberg radio telescope, shows a segment of the Milky Way's disk, revealing previously unseen tracers of massive star formation. Image Credit: Brunthaler et al., Sophia Dagnello, NRAO/AUI/NSF.

The researchers integrated the abilities of the Karl G. Jansky Very Large Array (VLA) from the National Science Foundation and the 100-m Effelsberg Telescope in Germany to generate high-quality data that would facilitate scientists in the future.

Stars that are 10 times heavier than the Sun are key components of the galaxy and strongly impact their surroundings. But comprehending the formation of these massive stars poses difficulty for astronomers.

In recent times, this issue was overcome by studying the Milky Way at a  range of wavelengths including infrared and radio. The latest survey known as GLOSTAR (Global view of the Star formation in the Milky Way) was developed to tap the widely enhanced capabilities out of an upgrade project completed in 2012. It offered the VLA to generate previously unobtainable data.

GLOSTAR has thrilled astronomers with fresh data related to the birth and death of massive stars, including the tenuous material between the stars.

The GLOSTAR research team published the study in the journal Astronomy & Astrophysics. They have mentioned the initial results of their study, including clear studies of various individual objects. Observations are underway and more results are to be published.

The survey detected telltale tracers of the initial stages of massive star formation, such as compact regions of hydrogen gas ionized by the strong radiation from young stars, and radio emission from methanol (wood alcohol) molecules with the ability to identify the location of very young stars deeply covered by the clouds of gas and dust which are responsible for their formation.

The survey discovered several new remnants of supernova explosions, which are considered to be the dramatic deaths of massive stars. Studies performed earlier have less than one-third of the anticipated number of supernova remnants present in the Milky Way. In the investigated region, the GLOSTAR increased more than twice the number found with the help of the VLA data alone, and more predicted to appear in the Effelsberg data.

This is an important step to solve this longstanding mystery of the missing supernova remnants.

Rohit Dokara, PhD Student and Study Lead Author, Max Planck Institute for Radioastronomy

Rohit is the lead author of a study about the remnants.

The GLOSTAR team integrated the information from the Effelsberg telescope and the VLA to yield the full view of the study region. The multi-antenna VLA, an interferometer, merges the signals from broadly separated antennas to create images with extremely high resolution that depicts small details.

But such systems at times lose their ability to detect large-scale structures. The 100-m Effelsberg telescope offers data on structures larger than those the VLA could detect, which makes the image complete.

This clearly demonstrates that the Effelberg telescope is still very crucial, even after 50 years of operation.

Andreas Brunthaler, Study First Author and Project Leader, Max Planck Institute for Radioastronomy

Visible light is powerfully adsorbed by dust, which could be easily penetrated by radio waves. Radio telescopes are necessary to reveal the dust-shrouded regions in which young stars are formed.

The results obtained from GLOSTAR, integrated with other radio and infrared surveys, “offers astronomers a nearly complete census of massive star-forming clusters at various stages of formation, and this will have lasting value for future studies,” stated team member William Cotton, of the National Radio Astronomy Observatory (NRAO), who is an expert in combining interferometer and single-telescope data.

GLOSTAR is the first map of the Galactic Plane at radio wavelengths that detects many of the important star formation tracers at high spatial resolution. The detection of atomic and molecular spectral lines is critical to determine the location of star formation and to better understand the structure of the Galaxy.

Dana Balser, National Radio Astronomy Observatory

According to the initiator of GLOSTAR, the MPIfR’s Karl Menten, “It’s great to see the beautiful science resulting from two of our favorite radio telescopes joining forces.”


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