8.3 and 12.4 micron imaging of the Galactic Center source complex with the Goddard infrared array camera

Gezari, D. Y.; Shu, P.; Lamb, G.; Fienberg, Richard Tresch; Fazio, G. G.; Hoffmann, W. F.; Gatley, I.; McCreight, Craig R.

doi:10.1086/163768

Cited by 31 publications

(26 citation statements)

References 18 publications

(41 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Therefore, our analysis of its size is performed in one dimension by comparing the azimuthally averaged intensity profile of IRS The contours plotted represent 90%-10% of the peak flux value in 10% increments. The source 0>5 northwest of IRS 21, discussed in x 3.2, is absent from the color map, suggesting that it is an externally heated region of higher dust density, as was originally suggested for IRS 21 by Gezari et al (1985). The cross represents the 2.2 lm position and uncertainty of IRS 21.…”

Section: Near-infrared Size Of Irs 21mentioning

confidence: 76%

“…Within the central parsec, IRS 21 has the largest K-band (2.2 lm) polarization, $10% (Ott, Eckart, & Genzel 1999;Eckart et al 1995), and is one of the few objects to have both extremely red colors (HÀK > 3) and a featureless K-band spectrum (Blum, Sellgren, & Depoy 1996;Krabbe et al 1995;Ott et al 1999). Gezari et al (1985) initially identified IRS 21 in 8.3 and 12.4 lm images as a strong mid-infrared peak located along the Northern Arm, a tidal stream of dust and gas (Gezari et al 1985;Lacy et al 1980) that is infalling toward and orbiting around the supermassive (M BH $ 2:6 Â 10 6 M ) central black hole Sgr A* (Genzel et al 1996(Genzel et al , 2000Ghez et al 1998Ghez et al , 2000. Along the Northern Arm, there are a handful of other similarly strong mid-infrared sources (L $ 10 4 10 5 L ), including IRS 1, 2, 5, 8, and 10 (nomenclature from Becklin et al 1978), which will be referred to collectively as the '' Northern Arm sources.''…”

Section: Introductionmentioning

confidence: 99%

“…Initially, Gezari et al (1985) suggested that IRS 21 is an externally heated, high-density dust clump. Several other classifications have also been proposed since then, including an embedded early-type star and a protostar (Krabbe et al 1995;Blum et al 1996;Ott et al 1999).…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Spatially Resolved Observations of the Galactic Center Source IRS 21

Tanner

Ghez

Morris

et al. 2002

ApJ

View full text Add to dashboard Cite

We present diffraction-limited 2-25 lm images obtained with the W. M. Keck 10 m telescopes that spatially resolve the cool source IRS 21, one of a small group of enigmatic objects in the central parsec of our Galaxy that have eluded classification. Modeled as a Gaussian, the azimuthally averaged intensity profile of IRS 21 has a half-width at half-maximum (HWHM) size of 650 AE 80 AU at 2.2 lm and an average HWHM size of 1600 AE 200 AU at mid-infrared wavelengths. These large apparent sizes imply an extended distribution of dust. The mid-infrared color map indicates that IRS 21 is a self-luminous source rather than an externally heated dust clump as originally suggested. The spectral energy distribution has distinct near-and midinfrared components. A simple radiative transfer code, which simultaneously fits the near-and mid-infrared photometry and intensity profiles, supports a model in which the near-infrared radiation is scattered and extincted light from an embedded central source, while the mid-infrared emission is from thermally reradiating silicate dust. We argue that IRS 21 (and by analogy, the other luminous sources along the Northern Arm) is a massive star experiencing rapid mass loss and plowing through the Northern Arm, thereby generating a bow shock, which is spatially resolved in our observations.

show abstract

Section: Near-infrared Size Of Irs 21mentioning

confidence: 76%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Spatially Resolved Observations of the Galactic Center Source IRS 21

Tanner

Ghez

Morris

et al. 2002

ApJ

View full text Add to dashboard Cite

show abstract

“…The best-studied case is IRS 21, which is strongly polarized (17% at 2 m ; Eckart et al 1995;Ott, Eckart, & Genzel 1999, Krabbe et al 1995. Initially, Gezari et al (1985) suggested that IRS 21 is an externally heated, high-density dust clump. Given the mid-infrared (MIR) excess and the featureless near-infrared (NIR) spectra, several other classifications have been proposed, including an embedded early-type star and a protostar (Krabbe et al 1995;Genzel et al 1996;Clénet et al 2001).…”

Section: Introductionmentioning

confidence: 99%

Young Stars at the Center of the Milky Way?

Eckart

Moultaka

Viehmann

et al. 2004

ApJ

View full text Add to dashboard Cite

We present results from the first diffraction-limited images of the Galactic center (GC) at 1.6, 2.1, and 3.8 m with the new adaptive optics (AO) camera NAOS/CONICA at the ESO Very Large Telescope, as well as 3-4 m low-resolution spectroscopy. We have discovered a small (0.13 lt-yr diameter) cluster of compact sources about 0B5 north of IRS 13 with strong IR excesses due to T > 500 K dust. The nature of the sources is unclear. They may be a cluster of highly extincted stars that heat the local environment of the minispiral. We also consider an explanation that involves the presence of young stars at evolutionary stages between young stellar objects and Herbig Ae/Be objects with ages of about 0.1 to 1 million yr. This scenario would imply more recent star formation in the GC than previously suspected. The AO observations also resolve the central IRS 13 complex. In addition to the previously known bright stars E1 and E2, the K-and L 0 -band images for the first time resolve object E3 into two components, E3N and E3c. The latter one is closest to the 7 mm Very Large Array radio continuum source found at the location of the IRS 13 complex. E3c may be associated with a strong stellar wind or a dusty Wolf-Rayet-like star at that location.

show abstract

“…Among the best studied cases is IRS 21, which is strongly polarized (17% at 2 µm; Eckart et al 1995;Ott et al 1999;Krabbe et al 1995). Initially, Gezari et al (1985) suggested that IRS 21 is an externally heated, highdensity dust clump. Given the MIR excess and the featureless NIR spectra several other classifications have been proposed, including an embedded early-type star and a protostar (Blum et al 1988;Krabbe et al 1995;Genzel et al 1996;Clénet et al 2001).…”

Section: Introductionmentioning

confidence: 99%

Dust embedded sources at the Galactic Center

Moultaka¹,

Eckart²,

Viehmann³

et al. 2004

A&A

View full text Add to dashboard Cite

Abstract. We present the first L-band spectroscopic observations of a dozen stellar sources in the central 0.5 pc of the GC stellar cluster that are bright in the 2−4 µm wavelength domain. The L-band data were taken with ISAAC at the VLT UT1 (Antu). With the aid of additional K-band spectroscopic data we derive the optical depth spectra of the sources after fitting their continuum emission with a single reddened blackbody continuum. We also derive intrinsic source spectra by correcting the line of sight extinction via the optical depth spectrum of a late type star that is most likely not affected by local dust emission or extinction at the Galactic Center. The good agreement between the two approaches shows that the overall variation of the line-of-sight extinction across the central 0.5 pc is ∆A K ≤ 0.5 mag. The extinction-corrected spectra of the hot He-stars resemble pure Rayleigh-Jeans continuum spectra. The intrinsic spectra of all other sources are in agreement with being the result of the continuum emission and absorption features due to the dust in which they are embedded. We interprete both facts as evidence that a significant amount of the absorption takes place within the central parsec of the Galactic Center and is most likely associated with the individual sources there. We find absorption features at 3.0 µm, 3.4 µm, and 3.48 µm wavelength. Correlations between all three features show that they are very likely to arise in the ISM of the central 0.5 pc. Spatially highly variable hydrogen emission lines seen towards the individual sources give evidence of the complex density and temperature structure of the mini-spiral. The featureless K-band spectra of sources like IRS 21 and IRS 1W are consistent with these sources being massive hot stars embedded in the bow shock created by their motion through the dust and gas of the mini-spiral. The bow shock scenario may be applicable to most of the dust-embedded sources in the central stellar cluster. Spectroscopy of high MIR-excess sources 0.5 north of the IRS 13 complex is largely consistent with them being YSOs. However, a bow-shock nature of these sources cannot be excluded. The L-band spectrum at the location of SgrA* closely resembles that of a hot O-type star, such as S2, which was very close to Sgr A* at the time of our observations.

show abstract

8.3 and 12.4 micron imaging of the Galactic Center source complex with the Goddard infrared array camera

Cited by 31 publications

References 18 publications

Spatially Resolved Observations of the Galactic Center Source IRS 21

Spatially Resolved Observations of the Galactic Center Source IRS 21

Young Stars at the Center of the Milky Way?

Dust embedded sources at the Galactic Center

Contact Info

Product

Resources

About