Volume 452, Number 1, June II 2006
|Page(s)||245 - 252|
|Section||Interstellar and circumstellar matter|
|Published online||17 May 2006|
Accretion in the -Ophiuchi pre-main sequence stars
Osservatorio Astrofisico di Arcetri, INAF, Largo E. Fermi 5, 50125 Firenze, Italy e-mail: firstname.lastname@example.org
Accepted: 20 February 2006
Aims.The aim of this paper is to provide a measurement of the mass accretion rate in a large, complete sample of objects in the core of the star forming region ρ Oph.
Methods.The sample includes most of the objects (104 out of 111) with evidence of a circumstellar disk from mid-infrared photometry; it covers a stellar mass range from about 0.03 to 3 and it is complete to a limiting mass of ~0.05 . We used J and K-band spectra to derive the mass accretion rate of each object from the intensity of the hydrogen recombination lines, Paβ or Brγ. For comparison, we also obtained similar spectra of 35 diskless objects.
Results.The results show that emission in these lines is only seen in stars with disks, and can be used as an indicator of accretion. However, the converse does not hold, as about 50% of our disk objects do not have detectable line emission. The measured accretion rates show a strong correlation with the mass of the central object ( ) and a large spread, of two orders of magnitude at least, for any interval of . A comparison with existing data for Taurus shows that the objects in the two regions have similar behaviour, at least for objects more massive than ∼0.1 . The implications of these results are briefly discussed.
Key words: stars: formation / accretion, accretion disks / stars: activity
© ESO, 2006
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.