Issue |
A&A
Volume 374, Number 2, August I 2001
|
|
---|---|---|
Page(s) | 554 - 563 | |
Section | Galactic structure, stellar clusters, and populations | |
DOI | https://doi.org/10.1051/0004-6361:20010741 | |
Published online | 15 August 2001 |
Open clusters or their remnants: and photometry of NGC 1901 and NGC 1252
1
Universidade Federal do Rio Grande do Sul, IF, CP 15051, Porto Alegre 91501-970, RS, Brazil
2
Observatorio Astronómico de Córdoba, Laprida 854, 5000, Córdoba, Argentina
Corresponding author: D. B. Pavani, dpavani@if.ufrgs.br
Received:
23
January
2001
Accepted:
21
May
2001
Photometry in the B and V bands is presented for the southern stellar groups NGC 1901 and NGC 1252. NGC 1901 is often described as an open cluster while NGC 1252 consists of a concentration of about 20 stars centered ≈20′ north of the original New General Catalogue coordinates, and at the southwest edge of the large region previously assigned to this object in the literature. NGC 1901 has a clear main sequence and shares similarities with the Hyades. We derive a reddening value , a distance from the Sun kpc ( kpc) and an age 0.6 ± 0.1 Gyr. NGC 1901 is conclusively a physical system, dynamically comparable to or more evolved than the Hyades. The colour-magnitude diagram of NGC 1252 suggests a turnoff and main sequence, and a total of 12 probable members. We simulated the Galactic field colour-magnitude diagram in the same direction and found it to be a poor match to NGC 1252, suggesting that NGC 1252 is not a field fluctuation. Isochrone fitting to the probable members is consistent with , kpc ( kpc) and an age 3 ± 1 Gyr. NGC 1252 cannot be ruled out as a physical group with the available data. If so, evidence is found that it is not a classical open cluster, but rather an open cluster remnant.
Key words: galaxy: open clusters and stellar associations / galaxies: individual: NGC 1901, NGC 1252
© ESO, 2001
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