TEXES Observations of Pure Rotational H2 Emission from AB Aurigae

We present observations of pure rotational molecular hydrogen emission from the Herbig Ae star, AB Aur. Our observations were made using the Texas Echelon Cross Echelle Spectrograph (TEXES) at the NASA Infrared Telescope Facility and the Gemini North Observatory. We searched for H2 emission in the S(1), S(2), and S(4) lines at high spectral resolution and detected all three. By fitting a simple model for the emission in the three transitions, we derive T = 670 ± 40 K and M = 0.52 ± 0.15 M⊕ for the emitting gas. On the basis of the 8.5 km s-1 FWHM of the S(2) line, assuming the emission comes from the circumstellar disk, and with an inclination estimate of the AB Aur system taken from the literature, we place the location for the emission near 18 AU. Comparison of our derived temperature to a disk structure model suggests that UV and X-ray heating are important in heating the disk atmosphere.

[1]  C. Dullemond,et al.  Chemistry and line emission from evolving Herbig Ae disks , 2006, astro-ph/0611223.

[2]  J. Najita,et al.  Neon Fine-Structure Line Emission by X-Ray Irradiated Protoplanetary Disks , 2006, astro-ph/0611094.

[3]  S. Wolf,et al.  Formation and Evolution of Planetary Systems: Upper Limits to the Gas Mass in Disks around Sun-like Stars , 2006, astro-ph/0606669.

[4]  B. Draine,et al.  H2 Pure Rotational Lines in the Orion Bar , 2005, astro-ph/0506003.

[5]  T. Millar,et al.  Molecular hydrogen emission from protoplanetary disks , 2005, astro-ph/0505126.

[6]  Millimeter Observations and Modeling of the AB Aurigae System , 2004, astro-ph/0411653.

[7]  J. Najita,et al.  Heating Protoplanetary Disk Atmospheres , 2004 .

[8]  U. Gorti,et al.  Models of Chemistry, Thermal Balance, and Infrared Spectra from Intermediate-Aged Disks around G and K Stars , 2004, astro-ph/0405244.

[9]  Geoffrey A. Blake,et al.  High-Resolution 4.7 Micron Keck/NIRSPEC Spectroscopy of the CO Emission from the Disks Surrounding Herbig Ae Stars , 2004 .

[10]  P. Berlind,et al.  Spectral Analysis and Classification of Herbig Ae/Be Stars , 2004 .

[11]  J. Najita,et al.  Gas in the Terrestrial Planet Region of Disks: CO Fundamental Emission from T Tauri Stars , 2003 .

[12]  C. Kulesa,et al.  CO Emission from Disks around AB Aurigae and HD 141569: Implications for Disk Structure and Planet Formation Timescales , 2003 .

[13]  C. Chen,et al.  The Mid-Infrared-emitting Dust around AB Aurigae , 2003, astro-ph/0303064.

[14]  J. Kastner,et al.  Detections of Rovibrational H2 Emission from the Disks of T Tauri Stars , 2003, astro-ph/0301124.

[15]  C. Dullemond,et al.  Vertical structure models of T Tauri and Herbig Ae/Be disks , 2002, astro-ph/0204281.

[16]  D. Jaffe,et al.  TEXES: A Sensitive High‐Resolution Grating Spectrograph for the Mid‐Infrared , 2001, astro-ph/0110521.

[17]  Astronomy,et al.  H2 and CO Emission from Disks around T Tauri and Herbig Ae Pre-Main-Sequence Stars and from Debris Disks around Young Stars: Warm and Cold Circumstellar Gas , 2001, astro-ph/0107006.

[18]  C. Dominik,et al.  Passive Irradiated Circumstellar Disks with an Inner Hole , 2001, astro-ph/0106470.

[19]  J. Bouwman,et al.  ISO spectroscopy of circumstellar dust in 14 Herbig Ae/Be systems: Towards an understanding of dust processing , 2000, astro-ph/0012295.

[20]  J. Valenti,et al.  An IUE Atlas of Pre-Main-Sequence Stars. II. Far-Ultraviolet Accretion Diagnostics in T Tauri Stars , 2000 .

[21]  V. Mannings,et al.  A High-Resolution Study of Gas and Dust around Young Intermediate-Mass Stars: Evidence for Circumstellar Disks in Herbig Ae Systems , 1997 .