J/A+A/466/931 UBVI photometry of NGC 1901 (Carraro+, 2007)
Observational templates of star cluster disruption.
The stellar group NGC 1901 in front of the Large Magellanic Cloud.
Carraro G., de la Fuente Marcos R., Villanova S., Moni Bidin C.,
de la Fuente Marcos C., Baumgardt H., Solivella G.
<Astron. Astrophys. 466, 931 (2007)>
=2007A&A...466..931C 2007A&A...466..931C
ADC_Keywords: Clusters, open ; Photometry, CCD ; Photometry, UBVRI
Keywords: Galaxy: open clusters and associations: individual: NGC 1901 -
Galaxy: evolution
Abstract:
Observations indicate that present-day star formation in the Milky Way
disk takes place in stellar ensembles or clusters rather than in
isolation. Bound, long-lived stellar groups are known as open
clusters. They gradually lose stars and are severely disrupted in
their final evolutionary stages, leaving an open cluster remnant made
up of a few stars.
In this paper, we study in detail the stellar content and kinematics
of the poorly populated star cluster NGC 1901. This object appears
projected against the Large Magellanic Cloud. The aim of the present
work is to derive the current evolutionary status, binary fraction,
age, and mass of this stellar group. These are fundamental quantities
to compare with those from N-body models in order to study the most
general topic of star cluster evolution and dissolution.
The analysis is performed using wide-field photometry in the UBVI
pass-band, proper motions from the UCAC.2 catalog, and 3 epochs of
high-resolution spectroscopy, as well as results from extensive
N-body calculations.
The star group NGC 1901 is found to be an ensemble of solar
metallicity stars, 400±100Myr old, with a core radius of 0.23pc,
a tidal radius of 1.0pc, and a location at 400±50pc from the
Sun. Out of 13 confirmed members, only 5 single stars have been found.
Its estimated present-day binary fraction is at least 62%. The
calculated heliocentric space motion of the cluster is not compatible
with possible membership in the Hyades stream.
Our results show that NGC 1901 is a clear prototype of an open cluster
remnant characterized by a high value of the binary fraction and a
significant depletion of low-mass stars. In light of numerical
simulations, this is compatible with NGC 1901 being what remains of a
larger system initially made of 500-750 stars.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 94 50000 Photometry of NGC 1901
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Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 5 I5 --- Seq [1/50000] Sequential number
7- 8 I2 h RAh Right ascension (J2000.0)
9 A1 --- --- [:]
10- 11 I2 min RAm Right ascension (J2000.0)
12 A1 --- --- [:]
13- 17 F5.2 s RAs Right ascension (J2000.0)
19 A1 --- DE- Declination sign (J2000.0)
20- 21 I2 deg DEd Declination (J2000.0)
22 A1 --- --- [:]
23- 24 I2 arcmin DEm Declination (J2000.0)
25 A1 --- --- [:]
26- 30 F5.2 arcsec DEs Declination (J2000.0)
32- 38 F7.4 mag Umag ?=99.9999 U magnitude
40- 46 F7.4 mag e_Umag ?=99.9999 error in U magnitude
48- 54 F7.4 mag Bmag ?=99.9999 B magnitude
56- 62 F7.4 mag e_Bmag ?=99.9999 Error in B magnitude
64- 70 F7.4 mag Vmag ?=99.9999 V magnitude
72- 78 F7.4 mag e_Vmag ?=99.9999 error in V magnitude
80- 86 F7.4 mag Imag ?=99.9999 I magnitude
88- 94 F7.4 mag e_Imag ?=99.9999 error in I magnitude
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Acknowledgements:
Giovanni Carraro, giovanni.carraro(at)unipd.it
(End) Giovanni Carraro [Padova, Italy], Patricia Vannier [CDS] 06-Mar-2007