An Extended Star Formation History for the Galactic Center from<i>Hubble Space Telescope</i>NICMOS Observations

Figer, Donald F.; Rich, R. Michael; Kim, Sungsoo S.; Serabyn, Eugene

doi:10.1086/380392

Cited by 185 publications

(230 citation statements)

References 51 publications

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“…By modeling the evolution of the population of luminous infrared stars, Figer et al (2004) suggests that the star formation is probably continuous over the last ∼10 Gyr, as we do in this paper. The Kroupa et al (1993) IMF adopted in this work has a slope of −2.7 when M > 1.0 M , derived from the stellar distribution towards both Galactic poles, as well as from the distribution of stars within 5.2 pc from the Sun.…”

Section: Star Formation and Imf In Gcrsupporting

confidence: 54%

A population synthesis study on the faint X-ray sources in the Galactic center region

Liu

2006

A&A

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Context. Recent Chandra observations of the Galactic center region (GCR) have uncovered a population of faint discrete X-ray sources. A few theoretical works have already investigated the nature of these sources. Aims. We examine the contributions and luminosity functions of various kinds of candidate objects that have been proposed either by previous authors or by ourselves. Methods. We conduct a population synthesis calculation based on the Hurley et al. rapid binary evolution code. Several candidate models, i.e. wind-accreting neutron stars, intermediate polars, low mass X-ray binaries, young pulsars, and massive stars with strong winds, are incorporated into our calculation. We also take the geometric effect of the accretion disk into account for Roche lobe overflow X-ray binaries. Results. Our results show that neutron star low-mass X-ray binaries contribute significantly to the observed sources. We also point out that wind-accreting neutron stars contribute negligible amount to these sources due to the propeller effect, and the intermediate polars play a minor role in accounting for the faint X-ray sources in both the Wang et al. and Muno et al. survey. It should be mentioned that the majority of the sources in the survey field of Wang et al. are still beyond what we can expect to find.

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Section: Star Formation and Imf In Gcrsupporting

confidence: 54%

A population synthesis study on the faint X-ray sources in the Galactic center region

Liu

2006

A&A

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“…Alexander & Sternberg (1999); Tiede et al (1995); Zoccali et al (2003) measured the power law slope of the bulge population of the milky way several degrees from the center as β ∼ 0.3, while Figer et al (2004) give the same value for the KLF on 30 pc scales around the GC, claiming that this value agrees very well with the theoretical KLF of an old stellar population, reflecting the rate of evolution of stars along the red giant and asymptotic giant branch. Genzel et al (2003) give a value of β = 0.21 ± 0.02 for the central 9 .…”

Section: K Band Luminosity Functionmentioning

confidence: 67%

Composition of the galactic center star cluster

Buchholz

Schödel

Eckart

2009

A&A

170

339

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Context. The GC is the closest galactic nucleus, offering the unique possibility of studying the population of a dense stellar cluster surrounding an SMBH. Aims. The goals of this work are to develop a new method of separating early and late type stellar components of a dense stellar cluster based on narrow band filters, applying it to the central parsec of the GC, and conducting a population analysis of this area. Methods. We use AO assisted observations obtained at the ESO VLT in the NIR H-band and 7 intermediate bands covering the NIR K-band. A comparison of the resulting SEDs with a blackbody of variable extinction then allows us to determine the presence and strength of a CO absorption feature to distinguish between early and late type stars.Results. This new method is suitable for classifying K giants (and later), as well as B2 main sequence (and earlier) stars that are brighter than 15.5 mag in the K band in the central parsec. Compared to previous spectroscopic investigations that are limited to 13-14 mag, this represents a major improvement in the depth of the observations and reduces the needed observation time. Extremely red objects and foreground sources can also be reliably removed from the sample. Comparison to sources of known classification indicates that the method has an accuracy of better than ∼87%. We classify 312 stars as early type candidates out of a sample of 5914 sources. Several results, such as the shape of the KLF and the spatial distribution of both early and late type stars, confirm and extend previous works. The distribution of the early type stars can be fitted with a steep power law (β 1 = −1.49 ± 0.12), alternatively with a broken power law, β 1−10 = −1.08 ± 0.12, β 10−20 = −3.46 ± 0.58, since we find a drop in the early type density at ∼10 . We also detect early type candidates outside of 0.5 pc in significant numbers for the first time. The late type density function shows an inversion in the inner 6 , with a power-law slope of β R<6 = 0.17 ± 0.09. The late type KLF has a power-law slope of 0.30 ± 0.01, closely resembling the KLF obtained for the bulge of the Milky Way. The early type KLF has a much flatter slope of (0.14 ± 0.02). Our results agree best with an in-situ star formation scenario.

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“…They are all located at the near-side of the Galaxy, suggesting that their census is highly incomplete (Messineo et al 2009). A few clusters e.g., the Westerlund I, Arches, and Quintuplet clusters (Westerlund 1961;Cotera et al 1996;Figer et al 1999Figer et al , 2002Figer et al , 2004Clark et al 2005) were known to be massive since the 1990s or even earlier and have been studied at various wavelengths. However, the Arches and the Quintuplet may not be representative of massive clusters elsewhere in the Milky Way because of the peculiar physical conditions in the Galactic center region.…”

Section: Red Supergiants In Stellar Clustersmentioning

confidence: 99%

SiO maser emission from red supergiants across the Galaxy

Verheyen¹,

Messineo²,

Menten³

2012

A&A

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Aims. Red supergiants (RSGs) are among the most luminous of all stars, easily detectable in external galaxies, and may ideally serve as kinematic tracers of Galactic structure. Some RSGs are surrounded by circumstellar envelopes detectable by their dust and molecular and, in particular, maser emission. This study consists of a search for maser emission from silicon monoxide (SiO) toward a significant number of RSGs that are members of massive stellar clusters, many of which have only recently been discovered. Further, we aim to relate the occurrence of maser action to properties of the host stars. Methods. Using the IRAM 30 m telescope, we searched for maser emission in the J = 2−1 rotational transition within the first vibrationally excited state of SiO toward a sample of 88 RSGs. Results. With an average rms noise level of 0.25 Jy, we detected maser emission in 15% of the sample, toward most of the sources for the first time in this transition. The peak of the emission provides accurate radial velocities for the RSGs. The dependence of the detection rate on infrared colors supports a radiative pumping mechanism for the SiO masers.

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An Extended Star Formation History for the Galactic Center fromHubble Space TelescopeNICMOS Observations

Cited by 185 publications

References 51 publications

A population synthesis study on the faint X-ray sources in the Galactic center region

A population synthesis study on the faint X-ray sources in the Galactic center region

Composition of the galactic center star cluster

SiO maser emission from red supergiants across the Galaxy

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