Recollimation Boundary Layers as X-Ray Sources in Young Stellar Jets
Abstract
Young stars accrete mass from circumstellar disks and, in many cases, the accretion coincides with a phase of massive outflows, which can be highly collimated. Those jets emit predominantly in the optical and IR wavelength range. However, in several cases, X-ray and UV observations reveal a weak but highly energetic component in those jets. X-rays are observed both from stationary regions close to the star and from knots in the jet several hundred AU from the star. In this article, we show semianalytically that a fast stellar wind that is recollimated by the pressure from a slower, more massive disk wind can have the right properties to power stationary X-ray emission. The size of the shocked regions is compatible with observational constraints. Our calculations support a wind-wind interaction scenario for the high-energy emission near the base of young stellar object jets. For the specific case of DG Tau, a stellar wind with a mass-loss rate of 5 × 10-10 M ⊙ yr-1 and a wind speed of 800 km s-1 reproduces the observed X-ray spectrum. We conclude that a stellar wind recollimation shock is a viable scenario to power stationary X-ray emission close to the jet launching point.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- November 2014
- DOI:
- 10.1088/0004-637X/795/1/51
- arXiv:
- arXiv:1409.0787
- Bibcode:
- 2014ApJ...795...51G
- Keywords:
-
- ISM: jets and outflows;
- shock waves;
- stars: formation;
- stars: individual: DG Tau;
- stars: mass-loss;
- stars: pre-main sequence;
- stars: winds;
- outflows;
- Astrophysics - Solar and Stellar Astrophysics
- E-Print:
- accepted by ApJ, 14 pages, 9 figures