VLT<i>L</i>-band mapping of the Galactic center IRS 3-IRS 13 region

Moultaka, J.; Eckart, A.; Schödel, R.; Viehmann, T.; Najarro, F.

doi:10.1051/0004-6361:20052819

Cited by 33 publications

(56 citation statements)

References 44 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…They are known to be less luminous than most other WR or OB giants, and there are a few of these objects in the GC field (see e.g. Moultaka et al 2005;Paumard et al 2006). The WR stars IRS7W with m K = 13.1, IRS7SE with m K = 13.0 (Martins et al 2007) and WR2 with m K = 12.9 (Moultaka et al 2005) are amongst the faintest known so far in the Galactic center cluster (for faint WR stars in the Milky Way see also Shara et al 1999Shara et al , 2012Mauerhan et al 2011 with survey limits around m K = 15.0).…”

Section: Proper Motions and Identification Of The Dsomentioning

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

View full text Add to dashboard Cite

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.

show abstract

Section: Proper Motions and Identification Of The Dsomentioning

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

View full text Add to dashboard Cite

show abstract

“…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. Allen et al 1990), with high mass-loss during this phase (Najarro et al 1994;Krabbe et al 1995;Morris et al 1996;Najarro et al 1997;Paumard et al 2001;Moultaka et al 2005). These stars account for a large part of the luminosity of the central cluster and also contribute half of the excitation/ionizing luminosity in this region (Rieke et al 1989;Najarro et al 1997;Eckart et al 1999;Paumard et al 2006;Martins et al 2007).…”

Section: Introductionmentioning

confidence: 99%

Composition of the galactic center star cluster

Buchholz

Schödel

Eckart

2009

A&A

Self Cite

172

339

View full text Add to dashboard Cite

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.

show abstract

“…However, it may be also a dusty envelope that enshrouds a star. Extended shells surrounding stars near Sgr A* have been reported, see for example Moultaka et al (2005).…”

Section: Role Of Central Starmentioning

confidence: 99%

“…The adopted scenario is not necessarily only connected to this single event. It may be applied to other observed infraredexcess stellar sources that have been shown to move through the gaseous medium near the Galactic centre (e.g., Moultaka et al 2005;Mužić et al 2010). Moreover, it may be relevant for modelling the environment in other low-luminosity active galactic nuclei.…”

Section: Introductionmentioning

confidence: 99%

Dust-enshrouded star near supermassive black hole: predictions for high-eccentricity passages near low-luminosity galactic nuclei

Karas

Eckart

2014

A&A

View full text Add to dashboard Cite

Context. Supermassive black holes reside in cores of galaxies, where they are often surrounded by a nuclear cluster and a clumpy torus of gas and dust. Mutual interactions can set some stars on a plunging trajectory towards the black hole. Aims. We model the pericentre passage of a dust-enshrouded star during which the dusty envelope becomes stretched by tidal forces and is affected by the interaction with the surrounding medium. In particular, we explore under which conditions these encounters can lead to periods of enhanced accretion activity. Methods. We discuss different scenarios for such a dusty source. To this end, we employed a modification of the Swift integration package. Elements of the cloud were modelled as numerical particles that represent the dust component that interacts with the optically thin gaseous environment. Results. We determine the fraction of the total mass of the dust component that is diverted from the original path during the passages through the pericentre at 10 3 Schwarzschild radii and find that the main part of the dust ( 90% of its mass) is significantly affected upon the first crossing. The fraction of mass captured at the second passage generally decreases to very low values. Conclusions. As an example, we show predictions for the dusty source evolution assuming the current orbital parameters of the G2 cloud (also known as Dusty S-Cluster Object, DSO) in our Galactic centre. Encounter of a core-less cloud with a supermassive black hole is, most likely, a non-repeating event: the cloud is destroyed. However, in the case of a dust-enshrouded star, part of the envelope survives the pericentre passage. We discuss an offset of 0.3 arcsec between the centre of mass of the diverted part and the star along the eccentric orbit. Finally, we examine an interesting possibility of a binary star embedded within a common wind envelope that becomes dispersed at the pericentre passage.

show abstract

VLTL-band mapping of the Galactic center IRS 3-IRS 13 region

Cited by 33 publications

References 44 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

Dust-enshrouded star near supermassive black hole: predictions for high-eccentricity passages near low-luminosity galactic nuclei

Contact Info

Product

Resources

About