English

High Resolution Optical and NIR Spectra of HBC 722

Solar and Stellar Astrophysics 2015-07-15 v1

Abstract

We present the results of high resolution (R\ge30,000) optical and near-IR spectroscopic monitoring observations of HBC 722, a recent FU Orionis object that underwent an accretion burst in 2010. We observed HBC 722 in optical/near-IR with the BOES, HET-HRS, and IGRINS spectrographs, at various points in the outburst. We found atomic lines with strongly blueshifted absorption features or P Cygni profiles, both evidence of a wind driven by the accretion. Some lines show a broad double-peaked absorption feature, evidence of disk rotation. However, the wind-driven and disk-driven spectroscopic features are anti-correlated in time; the disk features became strong as the wind features disappeared. This anti-correlation might indicate that the rebuilding of the inner disk was interrupted by the wind pressure during the first two years. The Half-Width at Half-Depth (HWHD) of the double-peaked profiles decreases with wavelength, indicative of the Keplerian rotation; the optical spectra with the disk feature are fitted by a G5 template stellar spectrum convolved with a rotation velocity of 70 km s1^{-1} while the near-IR disk features are fitted by a K5 template stellar spectrum convolved with a rotation velocity of 50 km s1^{-1}. Therefore, the optical and near-IR spectra seem to trace the disk at 39 and 76 R\textit{R}_{\odot}, respectively. We fit a power-law temperature distribution in the disk, finding an index of 0.8, comparable to optically thick accretion disk models.

Keywords

Cite

@article{arxiv.1505.03206,
  title  = {High Resolution Optical and NIR Spectra of HBC 722},
  author = {Jeong-Eun Lee and Sunkyung Park and Joel D. Green and William D. Cochran and Wonseok Kang and Sang-Gak Lee and Hyun-Il Sung},
  journal= {arXiv preprint arXiv:1505.03206},
  year   = {2015}
}

Comments

22 pages, 5 figures, accepted for publication in ApJ