They have also discovered 80 new supernova remnants (SNR) in the galaxy. The results have been published in a series of articles in Astronomy & Astrophysics by the team, which includes scientists from the IISc and the Indian Institute of Space Science and Technology (IIST).
Data for the survey was collected using two powerful radio telescopes: the Karl G Jansky Very Large Array (VLA) on the National Radio Astronomy Observatory (NRAO), USA, and the 100m Effelsberg Radio Telescope operated by the Max Planck Institute for Radio Astronomy (MPIfR), Germany, as part of the Milky Way Star Formation Global View (GLOSTAR) project.
According to a statement from IISc, Nirupam Roy, assistant professor, department of physics, IISc and Rohit Dokara, his former student, and Jagadheep D Pandian, associate professor, department of Earth and space sciences, IIST are among the Indian scientists that are part of GLOSTAR. .
Dokara, who is now pursuing a PhD at MPIfR, is the first author of one of the papers reporting on the detection of new supernova remnants (SNRs), structures born from the explosive death of massive stars.
“Previous surveys detected only about a third of the expected number of SNRs (almost 1,000). The GLOSTAR team has discovered 80 new SNR candidates in the VLA data alone, and more is expected from the combined Effelsberg and VLA data, ”said IISc.
The team also confirmed the presence of 77 previously discovered SNR candidates and reclassified some that were misidentified. “This is an important step in solving this ancient mystery of the lost supernova remnants,” says Dokara.
The researchers also detected other traces of star formation: one of them, for example, is the radio emission from methanol molecules in a large nearby star-formation complex called Cygnus X. These are usually emitted by massive stars in very early stages. training, said IISc. , adding that the team was also able to detect dense pockets of ionized hydrogen, another telltale sign of the presence of “massive young stars,” generally surrounded by thick clouds of dust and gas.
“… Because visible light is absorbed in this dense cloud around stars, most optical telescopes don’t reveal much. Instead, what people are looking for is radio broadcasts, ”explains Roy, who previously worked at both NRAO and MPIfR.
Pandian, who previously worked at MPIfR, explains that since the GLOSTAR study detects a wide range of radio emissions, it is capable of probing massive star formation from very early to relatively late stages, which is important for obtaining a complete picture. of the Milky Way star formation.
The Effelsberg radio telescope is a single large dish spanning 100 m in diameter, capable of detecting large-scale structures, while the VLA is a collection of small antennas that work together like an interferometer to capture high-resolution detail.
The data gathered from both telescopes helped the researchers paint a more complete picture of different astrophysical objects in the region, IISc said.
“This clearly shows that the Effelsberg telescope is still very crucial, even after 50 years of operation,” said Andreas Brunthaler of MPIfR, project leader and first author of the survey summary document.
Karl Menten, director of MPIfR who started GLOSTAR, adds: “It’s great to see the beautiful science resulting from two of our favorite radio telescopes joining forces.”
Both Pandian and Roy currently maintain Max Planck-India partner groups with Menten to continue the close collaboration and, in particular, to expand the scope of the GLOSTAR project.
Other members of the research team include scientists from MPIfR and NRAO, and collaborators from institutions in the UK, South Africa, Mexico, France and Australia. With the observations and analysis ongoing, more results are expected to be released over time, IISc added.