The earliest stages of star formation in Orion

Dense envelopes of gas and dust surround the fledging stars known as protostars, making their detection difficult until now. The discovery gives scientists a window into the earliest and least understood phases of star formation.
Image credit: Herschel Space Observatory

The Herschel Photodetector Array Camera and Spectrometer (PACS) instrument collected infrared light at 70 and 160 micrometers in wavelength, comparable to the width of a human hair. Researchers compared these observations to previous scans of the star-forming regions in Orion taken by Spitzer. Extremely young protostars identified in the Herschel views but too cold to be picked up in most of the Spitzer data were further verified with radio wave observations from the APEX ground telescope. Of the 15 newly discovered protostars, 11 possess very red colors, meaning their light output trends toward the low-energy end of the electromagnetic spectrum. This output indicates the stars are still embedded deeply in a gaseous envelope, meaning they are very young. An additional seven protostars previously seen by Spitzer share this characteristic. Together, these 18 budding stars comprise only five percent of the protostars and candidate protostars observed in Orion. That figure implies the very youngest stars spend perhaps 25,000 years in this phase of their development.

Top: the nebula Messier 78 is shown in a three-color composite from three telescopes: in green is the 160-micron, far-infrared light collected by Herschel’s Photodetector Array Camera and Spectrometer (PACS). Appearing in blue is 24-micron light from Spitzer. Finally, 870-micron radio wave light gathered by APEX glows red. Bottom: the same region appears in a separate three-color composite that shows infrared observations from two instruments aboard NASA’s Spitzer Space Telescope. Blue represents 3.6- and 4.5-micron light and green shows light of 5.8 and 8 microns, both captured by Spitzer’s Infrared Array Camera (IRAC). Red is 24-micron light detected by Spitzer’s Multiband Imaging Photometer (MIPS). Image credit: NASA/ESA/ESO/JPL-Caltech/Max-Planck Institute for Astronomy.

Messier_78
Image: ESO 2.2m/WFI La Silla Observatory

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One Response to “The earliest stages of star formation in Orion”

  1. […] The research paper is “A Herschel and APEX Census of the Reddest Sources in Orion: Searching for the Youngest Protostars” by A. Stutz et al., ApJ 767, 36 (2013) [ESO pdf]. For more on the young protostars in the region see here. […]

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