ALMA | ESO | NAOJ | NRAO | 2016 Aug 25
[img3="ALMA image of the debris disk surrounding a star in the Scorpius-Centaurus Association known as HIP 73145. The green region maps the carbon monoxide gas that suffuses the debris disk. The red is the millimeter-wavelength light emitted by the dust surrounding the central star. The star HIP 73145 is estimated to be approximately twice the mass of the Sun. The disk in this system extends well past what would be the orbit of Neptune in our solar system, drawn in for scale. The location of the central star is also highlighted for reference. Credit: J. Lieman-Sifry, et al., ALMA (ESO/NAOJ/NRAO); B. Saxton (NRAO/AUI/NSF)"]https://public.nrao.edu/images/pr/2016c ... e_nrao.jpg[/img3][hr][/hr]Astronomers using the Atacama Large Millimeter/submillimeter Array (ALMA) surveyed dozens of young stars – some Sun-like and others nearly double that size – and discovered that the larger variety have surprisingly rich reservoirs of carbon monoxide gas in their debris disks. In contrast, the lower-mass, Sun-like stars have debris disks that are virtually gas-free.
This finding runs counter to astronomer’s expectations, which hold that stronger radiation from larger stars should strip away gas from their debris disks faster than the comparatively mild radiation from smaller stars. It may also offer new insights into the timeline for giant planet formation around young stars.
Debris disks are found around stars that have shed their dusty, gas-filled protoplanetary disks and gone on to form planets, asteroids, comets, and other planetesimals. Around younger stars, however, many of these newly formed objects have yet to settle into stately orbits and routinely collide, producing enough rubble to spawn a "second-generation" disk of debris. ...
In search of clues as to why certain stars harbor gas-rich disks, Lieman-Sifry and his team surveyed 24 star systems in the Scorpius-Centaurus Association. This loose stellar agglomeration, which lies a few hundred light-years from Earth, contains hundreds of low- and intermediate-mass stars. For reference, astronomers consider our Sun to be a low-mass star.
The astronomers narrowed their search to stars between five and ten million years old -- old enough to host full-fledged planetary systems and debris disks -- and used ALMA to examine the millimeter-wavelength "glow" from the carbon monoxide in the stars’ debris disks. ...
Debris Disks in the Scorpius-Centaurus OB Association Resolved by ALMA - Jesse Lieman-Sifry et al
- Astrophysical Journal 828(1):25 (2016 Sep 01) DOI: 10.3847/0004-637X/828/1/25
arXiv.org > astro-ph > arXiv:1606.07068 > 22 Jun 2016