Issue |
A&A
Volume 440, Number 2, September III 2005
|
|
---|---|---|
Page(s) | 511 - 522 | |
Section | Galactic structure, stellar clusters, and populations | |
DOI | https://doi.org/10.1051/0004-6361:20052683 | |
Published online | 01 September 2005 |
NGC 146: a young open cluster with a Herbig Be star and intermediate mass pre-main sequence stars
1
Indian Institute of Astrophysics, II Block Koramangala, Bangalore 560034, India e-mail: purni@iiap.res.in
2
CREST Campus, Indian Institute of Astrophysics, Hosakote, Bangalore, India e-mail: dks@crest.ernet.in
3
Aryabhatta Research Institute of Observational Studies (ARIES), Manora peak, Nainital 263129, India e-mail: sagar@upso.ernet.in
4
VSRTP Student, Mother Theresa University, Kodaikanal, India
Received:
12
January
2005
Accepted:
11
May
2005
We present UBV CCD photometry and low-resolution spectra of stars in the
field of the young open cluster NGC 146. UBV photometry of 434 stars were used to
estimate the reddening of 0.55 ± 0.04 mag and BV photometry of 976 stars were used to estimate a distance modulus of
= 12.7 ± 0.2 mag, corresponding to a distance of 3470
pc. We estimated 10–16 Myr as the turn-off age for the upper
main sequence of the cluster using isochrones and synthetic colour magnitude diagrams.
We identified two B type stars with Hα in emission and
located on the MS using slit-less spectra. A higher resolution spectrum of the brighter Be star indicated the presence of a number of emission lines, with some lines showing the signature of gas infall. This star was found to be located in the region of Herbig Ae/Be stars in the
vs.
colour–colour diagram. Thus, we identify this star as a Herbig Be star.
On the other hand, 54 stars were found to show near infrared excess, of which 17 were found to be located in the region of Herbig Ae/Be stars and 18 stars were found to be located in the region of Be stars in the NIR colour–colour diagram. Thus NGC 146 is a young cluster with a large number of
intermediate mass pre-main sequence stars. The turn-on age of the cluster is found to be ~3 Myr. Though NGC 146 shows an older turn off,
the bulk of stars in this cluster seems to belong to the younger population of 3 Myr.
Key words: Galaxy: open cluster and associations: individual: NGC 146 / stars: emission-line, Be / stars: Hertzsprung-Russell (HR) and C-M diagrams / stars: pre-main sequence
© ESO, 2005
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