Near-infrared Imaging and Spectroscopic Survey of the Southern Region of the Young Open Cluster NGC 2264

Autor(en)

Naibí Mariñas, Elizabeth A. Lada, Paula S. Teixeira, Charles J. Lada

Abstrakt

We have obtained JHK near-IR images and JH band low-resolution spectra

of candidate members of the southern region of the young open cluster

NGC 2264. We have determined spectral types from H-band spectra for 54

sources, 25 of which are classified for the first time. The stars in our

sample cover a large range of spectral types (A8-M8). Using a cluster

distance of 780 pc, we determined a median age of 1 Myr for this region

of NGC 2264, with 90% of the stars being 5 Myr or younger. To improve

the statistical significance of our sample, we included 66 additional

cluster members within our field of view with optical spectral

classification in the literature. We derived infrared excesses using

stellar properties to model the photospheric emission for each source

and the extinction to correct FLAMINGOS near-IR and Spitzer mid-IR

photometry, and obtained a disk fraction of 51% ± 5% for the

region. Binning the stars by stellar mass, we find a disk fraction of

38% ± 9% for the 0.1-0.3 solar mass group, 55% ± 6% for

0.3-1 solar masses, and 58% ± 10% for the higher than 1 solar

mass group. The lower disk fraction for the lower mass stars is similar

to the results found in non-cluster regions like Taurus and Chamaeleon,

but differs from the older 3 Myr cluster IC 348 in which the disk

fraction is lower for the higher mass stars. This mass-dependent disk

fraction is accentuated in the sample with isochrone ages younger than 2

Myr. Here, we find that 45% ± 11% of the 0.1-0.3 solar mass stars

have disks, 60% ± 7% of the 0.3-1 solar mass stars have disks,

and all 1-3 solar mass stars have disks. Stellar masses might be an

important factor in the ability of a system to form or retain a disk

early on. However, regardless of the stellar mass, the large infrared

excesses expected from optically thick disks disappear within the first

2 Myr for all stars in our study and small excesses from optically thin

disks are found mostly in sources younger than 4 Myr.

 

Based on observations obtained at the KPNO.

Organisation(en)

Institut für Astrophysik

Externe Organisation(en)

University of Florida, Gainesville, Harvard-Smithsonian Center for Astrophysics

Journal

The Astrophysical Journal: an international review of astronomy and astronomical physics

Band

772

Anzahl der Seiten

21

ISSN

0004-637X

DOI

https://doi.org/10.1088/0004-637X/772/2/81

Publikationsdatum

08-2013

Peer-reviewed

Ja

ÖFOS 2012

103004 Astrophysik, 103003 Astronomie

Schlagwörter

Link zum Portal

https://ucrisportal.univie.ac.at/de/publications/541cc488-d0d9-4e16-a03f-6c7ef7d93930