Issue |
A&A
Volume 459, Number 3, December I 2006
|
|
---|---|---|
Page(s) | 837 - 842 | |
Section | Interstellar and circumstellar matter | |
DOI | https://doi.org/10.1051/0004-6361:20065575 | |
Published online | 12 September 2006 |
Accretion rates in Herbig Ae stars
1
INAF – Osservatorio Astrofisico di Arcetri, Largo Fermi 5, 50125 Firenze, Italy e-mail: natta@arcetri.astro.it
2
Università degli Studi di Roma “Tor Vergata” – Dipartimento di Fisica, via della Ricerca Scientifica 1, 00133 Roma, Italy
3
Université Paris-Sud, 91405 Orsay, France
Received:
9
May
2006
Accepted:
29
August
2006
Aims.Accretion rates from disks around pre-main sequence stars are of importance for our understanding of planetary formation and disk evolution. We provide in this paper estimates of the mass accretion rates in the disks around a large sample of Herbig Ae stars.
Methods.We obtained medium resolution
2 μm spectra and
used the results to compute
values of from the
measured luminosity of the Br
emission line, using
a well established correlation between L(Br
) and the accretion luminosity
Lacc.
Results.We find that 80% of the stars, all of which have evidence of an associated
circumstellar disk, are accreting matter, with rates
/yr; for 7
objects, 6 of which are located on the ZAMS in the
HR diagram, we do not detect any line emission. Few HAe stars
(25%) have
/yr.
Conclusions.In most HAe stars the accretion rate is sufficiently low that the gas in
the inner disk, inside the dust evaporation radius, is
optically thin and does not prevent the
formation of a puffed-up rim, where dust is directly exposed to the
stellar radiation.
When compared to the values found for lower-mass stars in the star
forming regions Taurus and Ophiuchus, HAe stars have on average higher
accretion rates than solar-mass stars; however, there is a lack of very strong accretors
among them, probably due to the fact that they are on average
older.
Key words: stars: formation / stars: circumstellar matter / stars: pre-main sequence / accretion, accretion disks
© 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.