Dr. Rachel Friesen of the University of Toronto and colleagues have captured a detailed image of a 50-light-year-long filament of star-forming gas in the Orion Molecular Cloud (OMC).
A ribbon of ammonia — a tracer of star-forming gas — in the Orion Molecular Cloud as seen with the GBT (orange); background in blue is an infrared image from NASA’s WISE telescope showing the dust in the region. Image credit: R. Friesen, Dunlap Institute / J. Pineda, MPIP / GBO / AUI / NSF / NASA.
The astronomers used NSF’s Robert C. Byrd Green Bank Telescope (GBT) to study the filament of star-forming gas that is wending its way through the northern portion of the OMC known as Orion A.
The GBT rendered the image by detecting the faint radio signals naturally emitted by molecules of ammonia that suffuse interstellar clouds.
“We still don’t understand in detail how large clouds of gas in our Galaxy collapse to form new stars,” Dr. Friesen said.
“But ammonia is an excellent tracer of dense, star-forming gas, and these large ammonia maps will allow us to track the motions and temperature of the densest gas.”
“This is critical to assessing whether gas clouds and filaments are stable, or are undergoing collapse on their way to forming new stars.”
The image accompanies the first release of results from the Green Bank Ammonia Survey (GAS), published in the Astrophysical Journal Supplement Series (arXiv.org preprint).
The release also includes the data for three other star-forming regions: B18 in the Taurus molecular cloud, NGC 1333 in the Perseus molecular cloud, and L1688 in the Ophiuchus molecular cloud.
“The goal of GAS is to survey all the major, nearby star-forming regions in the northern half of the Gould Belt — a ring of young stars and gas clouds that circles the entire sky and runs through the constellation Orion,” Dr. Friesen and co-authors said.
“The survey will eventually provide a clearer picture over a larger portion of the sky of the temperatures and motions of gas within these dynamic stellar nurseries.”
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Rachel K. Friesen et al. 2017. The Green Bank Ammonia Survey (GAS): First Results of NH3 mapping the Gould Belt. ApJS, in press; arXiv: 1704.06318
