Spectroscopy of Molecular Hydrogen Emission from KH 15D

Abstract

We report infrared spectroscopy of the unusual eclipsing pre-main sequence object KH 15D, obtained using NIRSPEC on Keck II. During eclipse, observations using low spectral resolution (1000) reveal the presence of prominent molecular hydrogen emission in 5 lines near 2 microns. The relative line strengths are consistent with thermal excitation at T = 2800 +/-300K. Observations out of eclipse, at both low and high spectral resolution (20,000), show reduced contrast with the stellar continuum. The change in contrast for the strongest line, 1-0 S(1), is consistent with an approximately constant emission line superposed on a variable stellar continuum. Emission in the 1-0 S(1) line is observed to extend by more than 4 arc-sec both east and west of the stellar point spread function (more than 3000 AU). Observed at high spectral resolution, the velocity and intensity structure of the 1-0 S(1) profile are both asymmetric. East of the stellar PSF (by 1.1 - 2.3 arc-sec) the emission is blueshifted (-63 km/sec), and has significantly greater intensity than the marginally redshifted component (+2 km/sec, consistent with zero) which dominates west of the stellar PSF. The spatial extent of the emission, and the excitation temperature, suggest shock-excitation of ambient gas by a bipolar outflow from the star and/or disk. However, it is difficult to account for the observed radial velocity unless the outflow axis is inclined significantly to the plane of the sky.

arXiv commentAccepted for ApJ Letters

References in corpus (8)

• Detections of Ro-Vibrational H${}_2$ Emission from the Disks of T Tauri Stars
• Eclipses by a Circumstellar Dust Feature in the Pre-Main Sequence Star KH15D
• Fine Structure in the Circumstellar Environment of a Young, Solar-like Star: the Unique Eclipses of KH 15D
• Natural Coronagraphic Observations of the Eclipsing T Tauri System KH 15D: Evidence for Accretion and Bipolar Outflow in a WTTS
• Spectropolarimetry and Modeling of the Eclipsing T Tauri Star KH 15D
• Limits on eclipses of the pre-main-sequence star KH 15D in the first half of the 20th century
• KH15D: a star eclipsed by a large scale dusty vortex?
• H${}_2$ Emission Nebulosity Associated with KH 15D

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• Locating the Trailing Edge of the Circumbinary Ring in the KH 15D System
• Alignment of a circumbinary disc around an eccentric binary with application to KH 15D
• The Disappearing Act of KH 15D: Photometric Results from 1995 to 2004
• Molecular Hydrogen emission from disks in the eta Chamaeleontis cluster
• H${}_2$ Emission Nebulosity Associated with KH 15D
• The History of the Mysterious Eclipses of KH 15D II. Asiago, Kiso, Kitt Peak, Mt. Wilson, Palomar, Tautenburg and Rozhen Observatories, 1954-97
• Complex Variability of the H$\alpha$ Emission Line Profile of the T Tauri Binary System KH 15D: The Influence of Orbital Phase, Occultation by the Circumbinary Disk, and Accretion Phenomenae
• Near-Infrared Photometric Monitoring of a Pre-Main-Sequence Object KH 15D
• Optical and Radio Observations of the T Tauri Binary KH 15D (V582 Mon): Stellar Properties, Disk Mass Limit and Discovery of a CO Outflow
• Blue and IR Light Curves of the Mysterious Pre-Main Sequence Star V582 Mon (KH 15D) from 1955 to 1970
• Seeing Through the Ring: Near-Infrared Photometry of V582 Mon (KH 15D)
• X-ray Emission from the Weak-lined T Tauri Binary System KH 15D
• Gas Absorption in the KH 15D System: Further Evidence for Dust Settling in the Circumbinary Disk
• Untangling the Near-IR Spectral Features in the Protoplanetary Environment of KH 15D
• Double-peaked OI profile: a likely signature of the gaseous ring around KH 15D
• The Unique Eclipsing System KH 15D: New Photometric Data