Young Stars at the Center of the Milky Way?

Eckart, A.; Moultaka, J.; Viehmann, T.; Straubmeier, C.; Mouawad, N.

doi:10.1086/381178

Cited by 52 publications

(108 citation statements)

References 59 publications

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“…In each epoch the faint K s -band counterparts of the significantly brighter L -band sources had to be identified. A first identification for epoch 2002 was given by Eckart et al (2004). The K s -band sources are faint compared to the IRS13E sources and deconvolution or point spread function (PSF) fitting is not sufficient to provide source identifications for all epochs.…”

Section: Proper Motions Of Irs13n and Irs13ementioning

confidence: 99%

Near-infrared proper motions and spectroscopy of infrared excess sources at the Galactic center

Eckart¹,

Mužić²,

Yazici³

et al. 2013

A&A

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152

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Context. There are a number of faint compact infrared excess sources in the central stellar cluster of the Milky Way. Their nature and origin is unclear. In addition to several isolated objects of this kind there is a small but dense cluster of comoving sources (IRS13N) located ∼3 west of SgrA* just 0.5 north of the bright IRS13E cluster of Wolf-Rayet and O-type stars. Based on the analysis of their color and brightness, there are two main possibilities: (1) they may be dust-embedded stars older than a few Myr; or (2) very young, dusty stars with ages younger than 1 Myr. Aims. We present a first K s -band identification and proper motions of the IRS13N members, the high-velocity dusty S-cluster object (DSO, also referred to as G2), and other infrared excess sources in the central field. Goal is to constrain the nature of these source. Methods. The L -(3.8 μm) K s -(2.2 μm) and H-band (1.65 μm) observations were carried out using the NACO adaptive optics system at the ESO VLT. Proper motions were obtained by linear fitting of the stellar positions extracted by StarFinder as a function of time, weighted by positional uncertainties, and by Gaussian fitting from high-pass filtered and deconvolved images. We also present results of near-infrared (NIR) H-and K s -band ESO-SINFONI integral field spectroscopy of the Galactic center cluster ISR13N. Results. We show that within the uncertainties, the positions and proper motions of the IRS13N sources in K s -and L -band are identical. The HK−sL colors then indicate that the bright L -band IRS13N sources are indeed dust-enshrouded stars rather than core-less dust clouds. The proper motions also show that the IRS13N sources are not strongly gravitationally bound to each other. Combined with their NIR colors, this implies that they have been formed recently. For the DSO we obtain proper motions and a K s -L -color. Conclusions. Most of the compact L -band excess emission sources have a compact H-or K s -band counterpart and therefore are likely stars with dust shells or disks. Our new results and orbital analysis from our previous work favor the hypothesis that the infrared excess IRS13N members and other dusty sources close to SgrA* are young dusty stars and that star formation at the Galactic center (GC) is a continuously ongoing process. For the DSO the color information indicates that it may be a dust cloud or a dust-embedded star.

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Section: Proper Motions Of Irs13n and Irs13ementioning

confidence: 99%

Near-infrared proper motions and spectroscopy of infrared excess sources at the Galactic center

Eckart¹,

Mužić²,

Yazici³

et al. 2013

A&A

Self Cite

152

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“…These stars can be found, e.g., in the IRS 16 and IRS 13 associations (e.g. Eckart et al 2004;Maillard et al 2004;Lu et al 2005). The brightest of those young stars have been described as stars in a transitional phase between O supergiants and Wolf-Rayet stars (WN9/Ofpe according to e.g.…”

Section: Introductionmentioning

confidence: 99%

Composition of the galactic center star cluster

Buchholz

Schödel

Eckart

2009

A&A

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174

355

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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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“…The central wind is probably produced by the collimated jet resulting from the accretion of the mass-loss material by the central stellar cluster as only 1% of this mass is accreted into the black hole and the remainder is blown away in a central wind (Quataert 2003). This work is in progress and will be presented in a forthcoming paper Eckart et al (2004).…”

Section: Filamentary Structures In the Central Parsecmentioning

confidence: 98%

“…In both cases, extinctions well above A V ∼ 30 mag are needed. The third interpretation is that they may be young stellar objects as they show similar luminosities (∼ 10 3 L ) in addition to their red colours and, when corrected from the visual extinction value A V ∼30 mag toward the Galactic Center, their colours are shifted to the region of YSO and Herbig Ae/Be stars in the Colour-Colour diagram (Ishii et al 1998) (see Eckart et al 2004 for further discussion). In addition, the ISAAC spectrum of the IRS 13N region has been well fitted with a reddened blackbody continuum of temperature T=1000K (see Fig.…”

Section: Young Stars At the Northern Part Of The Irs 13 Complexmentioning

confidence: 99%

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IR excess stars and shock filaments at the Galactic center

Moultaka¹,

Eckart²,

Viehmann³

et al. 2004

Proc. IAU

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Abstract. In this paper we report on our recent results connected with the direct environment of the super massive black hole of the Milky Way. The data are obtained using the VLT facilities (ISAAC and NAOS/CONICA instruments) in the near-and mid-infrared wavelength ranges. We provide a calibration of the foreground and local differential (in wavelength and spatially) extinction of the Galactic Center and report on the discovery of a new complex of infrared excess sources (possibly young stars) located at the northern part of the IRS 13 cluster. Finally, we discuss the origin of filamentary structures observed in the L-band images.

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Young Stars at the Center of the Milky Way?

Cited by 52 publications

References 59 publications

Near-infrared proper motions and spectroscopy of infrared excess sources at the Galactic center

Near-infrared proper motions and spectroscopy of infrared excess sources at the Galactic center

Composition of the galactic center star cluster

IR excess stars and shock filaments at the Galactic center

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