Abstract
We present WFPC2 and ground-based VI photometry of NGC 121 and a nearby field in the outer SMC. For NGC 121, we measure a true distance modulus of μ0 = 18.96 ± 0.04 (distance of 61.9 ± 1.1 kpc), age of 10.6 ± 0.5 Gyr, metallicity of [Fe/H] = -1.03 ± 0.06, and initial mass of 4.1 ± 0.4 × 105 M⊙, assuming a Salpeter IMF with lower cutoff at 0.1 M⊙. In the outer SMC field, we find evidence of stars covering a wide range of ages - from 2 Gyr to at least 9-12 Gyr old. We have measured the distance, extinction, and star formation history (past star formation rates and enrichment history) using a CMD-fitting algorithm. The distance modulus of the SMC is measured to be μ0 = 18.88 ± 0.08, corresponding to a distance of 59.7 ± 2.2 kpc. The overall star formation rate appears to have been relatively constant over this period, although there may be small gaps in the star-forming activity too small to be resolved. The lack of current star-forming activity is a selection effect, as the field was intentionally chosen to avoid recent activity. The mean metallicity of this field has increased from an average of [Fe/ H] = -1.3 ± 0.3 for stars older than 8 Gyr to [Fe/H] = -0.7 ± 0.2 in the past 3 Gyr.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 303-313 |
| Number of pages | 11 |
| Journal | Astrophysical Journal |
| Volume | 562 |
| Issue number | 1 PART I |
| DOIs | |
| State | Published - 2001 |
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Keywords
- Galaxies: evolution
- Galaxies: stellar content
- Magellanic Clouds
ASJC Scopus subject areas
- Space and Planetary Science
Cite this
Old stellar populations of the small magellanic cloud. / Dolphin, Andrew E.; Walker, Alistair R.; Hodge, Paul W.; Mateo, Mario; Olszewski, Edward W; Schommer, Robert A.; Suntzeff, Nicholas B.
In: Astrophysical Journal, Vol. 562, No. 1 PART I, 2001, p. 303-313.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Old stellar populations of the small magellanic cloud
AU - Dolphin, Andrew E.
AU - Walker, Alistair R.
AU - Hodge, Paul W.
AU - Mateo, Mario
AU - Olszewski, Edward W
AU - Schommer, Robert A.
AU - Suntzeff, Nicholas B.
PY - 2001
Y1 - 2001
N2 - We present WFPC2 and ground-based VI photometry of NGC 121 and a nearby field in the outer SMC. For NGC 121, we measure a true distance modulus of μ0 = 18.96 ± 0.04 (distance of 61.9 ± 1.1 kpc), age of 10.6 ± 0.5 Gyr, metallicity of [Fe/H] = -1.03 ± 0.06, and initial mass of 4.1 ± 0.4 × 105 M⊙, assuming a Salpeter IMF with lower cutoff at 0.1 M⊙. In the outer SMC field, we find evidence of stars covering a wide range of ages - from 2 Gyr to at least 9-12 Gyr old. We have measured the distance, extinction, and star formation history (past star formation rates and enrichment history) using a CMD-fitting algorithm. The distance modulus of the SMC is measured to be μ0 = 18.88 ± 0.08, corresponding to a distance of 59.7 ± 2.2 kpc. The overall star formation rate appears to have been relatively constant over this period, although there may be small gaps in the star-forming activity too small to be resolved. The lack of current star-forming activity is a selection effect, as the field was intentionally chosen to avoid recent activity. The mean metallicity of this field has increased from an average of [Fe/ H] = -1.3 ± 0.3 for stars older than 8 Gyr to [Fe/H] = -0.7 ± 0.2 in the past 3 Gyr.
AB - We present WFPC2 and ground-based VI photometry of NGC 121 and a nearby field in the outer SMC. For NGC 121, we measure a true distance modulus of μ0 = 18.96 ± 0.04 (distance of 61.9 ± 1.1 kpc), age of 10.6 ± 0.5 Gyr, metallicity of [Fe/H] = -1.03 ± 0.06, and initial mass of 4.1 ± 0.4 × 105 M⊙, assuming a Salpeter IMF with lower cutoff at 0.1 M⊙. In the outer SMC field, we find evidence of stars covering a wide range of ages - from 2 Gyr to at least 9-12 Gyr old. We have measured the distance, extinction, and star formation history (past star formation rates and enrichment history) using a CMD-fitting algorithm. The distance modulus of the SMC is measured to be μ0 = 18.88 ± 0.08, corresponding to a distance of 59.7 ± 2.2 kpc. The overall star formation rate appears to have been relatively constant over this period, although there may be small gaps in the star-forming activity too small to be resolved. The lack of current star-forming activity is a selection effect, as the field was intentionally chosen to avoid recent activity. The mean metallicity of this field has increased from an average of [Fe/ H] = -1.3 ± 0.3 for stars older than 8 Gyr to [Fe/H] = -0.7 ± 0.2 in the past 3 Gyr.
KW - Galaxies: evolution
KW - Galaxies: stellar content
KW - Magellanic Clouds
UR - http://www.scopus.com/inward/record.url?scp=0010448895&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0010448895&partnerID=8YFLogxK
U2 - 10.1086/323873
DO - 10.1086/323873
M3 - Article
AN - SCOPUS:0010448895
VL - 562
SP - 303
EP - 313
JO - Astrophysical Journal
JF - Astrophysical Journal
SN - 0004-637X
IS - 1 PART I
ER -