Near-Infrared Spectra of the Black Hole X-Ray Binary, A0620-00
| Autor: | Froning, C. S., Robinson, E. L., Bitner, M. A. |
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| Rok vydání: | 2007 |
| Předmět: | |
| Zdroj: | Astrophys.J.663:1215-1224,2007 |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1086/518820 |
| Popis: | We present broadband NIR spectra of A0620-00 obtained with SpeX on the IRTF. The spectrum is characterized by a blue continuum on which are superimposed broad emission lines of HI and HeII and a host of narrower absorption lines of neutral metals and molecules. Spectral type standard star spectra scaled to the dereddened spectrum of A0620-00 in K exceed the A0620-00 spectrum in J and H for all stars of spectral type K7V or earlier, demonstrating that the donor star, unless later than K7V, cannot be the sole NIR flux source in A0620-00. In addition, the atomic absorption lines in the K3V spectrum are too weak with respect to those of A0620-00 even at 100% donor star contribution, restricting the spectral type of the donor star in A0620-00 to later than K3V. Comparison of the A0620-00 spectrum to scaled K star spectra indicates that the CO absorption features are significantly weaker in A0620-00 than in field dwarf stars. Fits of scaled model spectra of a Roche lobe-filling donor star to the spectrum of A0620-00 show that the best match to the CO absorption lines is obtained when the C abundance is reduced to [C/H] = -1.5. The donor star contribution in the H waveband is determined to be 82+-2%. Combined with previous published results from Froning & Robinson (2001) and Marsh et al. (1994), this gives a precise mass for the black hole in A0620-00 of M_BH = 9.7+-0.6 M_solar. Comment: Accepted for publication in the Astrophysical Journal |
| Databáze: | arXiv |
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