Comparison between accretion-related properties of Herbig Ae/Be and T Tauri stars

Abstract

This paper summarizes several results concerning the comparison between accretion-related properties of cool (T Tauri; T < 7000 K, M < 1 Msun and hot (Herbig Ae/Be; 7000 < T(K) < 13000; 1 < M(Msun) < 6) pre-main sequence (PMS) stars. This comparison gives insight into the analogies/differences in the physics of the star-disk interaction and in the physical mechanisms driving disk dissipation. Several optical and near-IR line luminosities used for low-mass objects are also valid to estimate typical accretion rates for intermediate-mass stars under similar empirical expressions. In contrast, the Halpha width at 10% of peak intensity is used as an accretion tracer for T Tauris, but is not reliable to estimate accretion rates for Herbig Ae/Bes. This can be explained as a consequence of the different stellar rotation rates that characterize both types of stars. In addition, there are similar trends when the accretion rate is related to the near-IR colours and disk masses, suggesting that viscous accretion disk models are able to explain these trends for both T Tauri and Herbig Ae/Be stars. However, there are two major differences between cool and hot PMS objects. First, the inner gas dissipation timescale, as estimated by relating the accretion rates and the stellar ages, is slightly faster for Herbig Ae/Be stars. This could have implications on the physical mechanism able to form planets around objects more massive than the Sun. Second, the relative position of Herbig Ae/Bes with disks showing signs of inner dust clearing in the accretion rate--disk mass plane contrasts with that of transitional T Tauri stars, when both samples are compared with "classical", non-evolved disks. This latter difference could be pointing to a different physical mechanism driving disk evolution, depending on the stellar regime.

arXiv commentProceding article of the CoolStars 17 conference (June 2012, Barcelona). Published in Astronomische Nachrichten

References in corpus (24)

• Very Low Mass Stars and Brown Dwarfs in Taurus-Auriga
• Timescale of Mass Accretion in Pre-Main-Sequence Stars
• Accretion in Brown Dwarfs: an Infrared View
• UV excess measures of accretion onto young very low-mass stars and brown dwarfs
• A Submillimeter View of Circumstellar Dust Disks in $\rho$ Ophiuchus
• Star and protoplanetary disk properties in Orion's suburbs
• Accretion Rates in Herbig Ae stars
• Dust dynamics during protoplanetary disc clearing
• Magnetospheres and Disk Accretion in Herbig Ae/Be Stars
• Demographics of Transition Objects
• Probing the circumstellar structure of Herbig Ae/Be stars
• A search for strong, ordered magnetic fields in Herbig Ae/Be stars
• Accretion rates and accretion tracers of Herbig Ae/Be stars
• Extrasolar planets and brown dwarfs around A-F type stars VI. High precision RV survey of early type dwarfs with HARPS
• Accretion in protoplanetary disks: the imprint of core properties
• Searching for a link between the magnetic nature and other observed properties of Herbig Ae/Be stars and stars with debris disks
• Accretion-related properties of Herbig Ae/Be stars. Comparison with T Tauris
• Optical spectroscopic variability of Herbig Ae/Be stars
• POISSON project - II - A multi-wavelength spectroscopic and photometric survey of young protostars in L 1641
• On the difference between Herbig Ae and Herbig Be stars
• Looking for Pure Rotational H_2 Emission from Protoplanetary Disks
• X-shooter observations of the accreting brown dwarf J053825.4-024241
• Continuum and line modeling of disks around young stars II. Line diagnostics for GASPS from the DENT grid
• Tracing Accretion onto Herbig Ae/Be Stars using Near-Infrared Spectroscopy

Cited by in corpus (1)

• On the origin of the correlations between the accretion luminosity and emission line luminosities in pre-main sequence stars