The structure of disks around Herbig Ae/Be stars as traced by CO ro-vibrational emission

Abstract

We study the emission and absorption of CO ro-vibrational lines in the spectra of intermediate mass pre-main-sequence stars with the aim to determine both the spatial distribution of the CO gas and its physical properties. We also aim to correlate CO emission properties with disk geometry. Using high-resolution spectra containing fundamental and first overtone CO ro-vibrational emission, observed with CRIRES on the VLT, we probe the physical properties of the circumstellar gas by studying its kinematics and excitation conditions. We detect and spectrally resolve CO fundamental ro-vibrational emission in 12 of the 13 stars observed, and in two cases in absorption. Keeping in mind that we studied a limited sample, we find that the physical properties and spatial distribution of the CO gas correlate with disk geometry. Flaring disks show highly excited CO fundamental emission up to v${}_u$ = 5, while self-shadowed disks show CO emission that is not as highly excited. Rotational temperatures range between ~250-2000 K. The ${}^{13}$CO rotational temperatures are lower than those of ${}^{12}$CO. The vibrational temperatures in self-shadowed disks are similar to or slightly below the rotational temperatures, suggesting that thermal excitation or IR pumping is important in these lines. In flaring disks the vibrational temperatures reach as high as 6000 K, suggesting fluorescent pumping. Using a simple kinematic model we show that the CO inner radius of the emitting region is $\approx$10 au for flaring disks and $\le$ 1 au for self-shadowed disks. (abstract truncated due to 1920 character limit for arXiv)

Accepted in Astronomy and Astrophysics at 25 11 2014. 26 pages, 12 figures

References in corpus (11)

• Accretion Rates in Herbig Ae stars
• Spectro-astrometric imaging of molecular gas within protoplanetary disk gaps
• The origin of hydrogen line emission for five Herbig Ae/Be stars spatially resolved by VLTI/AMBER spectro-interferometry
• Few Skewed Disks Found in First Closure-Phase Survey of Herbig Ae/Be stars
• Tracing the inner edge of the disk around HD 100546 with Ro-vibrational CO Emission Lines
• The magnetic field of the pre-main sequence Herbig Ae star HD 190073
• Investigating the inner discs of Herbig Ae/Be stars with CO bandhead and Br Gamma emission
• Constraining the structure of the transition disk HD 135344B (SAO 206462) by simultaneous modeling of multiwavelength gas and dust observations
• The Structure of Protoplanetary Disks Surrounding Three Young Intermediate Mass Stars. I. Resolving the disk rotation in the [OI] 6300 Åline
• Multiplicity of young stars in and around R Corona Australis
• Centimeter Imaging of the R Coronae Australis Region

Cited by in corpus (18)

• A cavity and further radial substructures in the disk around HD~97048
• The depletion of water during dispersal of planet-forming disk regions
• ALMA reveals the anatomy of the mm-sized dust and molecular gas in the HD 97048 disk
• Scanning disk rings and winds in CO at 0.01-10 au: a high-resolution $M$-band spectroscopy survey with IRTF-iSHELL
• The kinematics and excitation of infrared water vapor emission from planet-forming disks: results from spectrally-resolved surveys and guidelines for JWST spectra
• A 80 au cavity in the disk around HD 34282
• Herbig Stars: A Quarter Century of Progress
• A gas density drop in the inner 6 AU of the transition disk around the Herbig Ae star HD 139614: Further evidence for a giant planet inside the disk?
• Identification of High Mass X-ray Binaries selected from XMM-Newton observations of the LMC
• A model exploration of NIR ro-vibrational CO emission as a tracer of inner cavities in protoplanetary disks
• A dichotomy in group II Herbig disks: ALMA gas disk height measurements show both shadowed large vertically extended disks and compact flat disks
• The GRAVITY Young Stellar Object survey VIII. Gas and dust faint inner rings in the hybrid disk of HD141569
• An SMA Survey of Chemistry in Disks around Herbig AeBe Stars
• Water and OH Emission from the inner disk of a Herbig Ae/Be star
• A Study of Ro-vibrational OH Emission from Herbig Ae/Be Stars
• Modeling of CO ro-vibrational line emission of HD 141569
• Investigating the nature of the extended structure around the Herbig star RCrA using integral field and high-resolution spectroscopy
• Molecules with ALMA at Planet-forming Scales (MAPS). XV. Tracing protoplanetary disk structure within 20 au