2010A&A...511A..18S


Query : 2010A&A...511A..18S

2010A&A...511A..18S - Astronomy and Astrophysics, volume 511, A18-18 (2010/2-2)

Peering through the veil: near-infrared photometry and extinction for the Galactic nuclear star cluster. Accurate near infrared H, Ks, and L' photometry and the near-infrared extinction-law toward the central parsec of the Galaxy.

SCHOEDEL R., NAJARRO F., MUZIC K. and ECKART A.

Abstract (from CDS):

The nuclear star cluster of the Galaxy is an important template for understanding its extragalactic counterparts, which can currently not be resolved into individual stars. Important drawbacks of observations of the Galactic center are, however, the presence of strong and spatially highly variable interstellar extinction and extreme crowding of the sources, which makes the use of adaptive optics techniques necessary. Both points pose serious obstacles to precise photometry that is needed for analyzing the stellar population. The aims of this work are to provide accurate photometry in multiple near-infrared broadband filters, to determine the power-law index of the extinction-law toward the central parsec of the Galaxy, to provide measurements of the absolute extinction toward the Galactic center, and finally to measure the spatial variability of extinction on arcsecond scales. We use observations of the central parsec of the Milky Way that were obtained with the near-infrared camera and adaptive optics system NAOS/CONICA at the ESO VLT unit telescope 4. The photometric method takes into account anisoplanatic effects and limits the corresponding systematic uncertainties to ≲2%. Absolute values for the extinction in the H, Ks, and L'-bands as well as of the power-law indices of the H to Ks and Ks to L' extinction-laws are measured based on the well-known properties of red clump stars. Extinction maps are derived based on H-Ks and Ks-L' colors. We present Ks-band photometry for ∼7700 stars, and additionally photometry for stars detected in the H and/or L'-bands. From a number of recently published values we compute a mean distance of the Galactic center of R0=8.03±0.15kpc, which has an uncertainty of just 2%. Based on this R0 and on the RC method, we derive absolute mean extinction values toward the central parsec of the Galaxy of AH=4.48±0.13mag, AKs=2.54±0.12mag, and AL'=1.27±0.18mag. We estimate values of the power-law indices of the extinction-law of αH–Ks=2.21±0.24 and αKs–L'=1.34±0.29. A Ks-band extinction map for the Galactic center is computed based on this extinction law and on stellar H-Ks colors. Both its statistical and systematic uncertainties are estimated to be <10%. Extinction in this map derived from stellar color excesses is found to vary on arcsecond scales, with a mean value of AKs=2.74±0.30mag. Mean extinction values in a circular region with 0.5'' radius centered on SagittariusA* are A_H, SgrA*_=4.35±0.12, A_Ks, SgrA*_=2.46±0.03, and A_L', SgrA*_=1.23±0.08.

Abstract Copyright:

Journal keyword(s): Galaxy: nucleus - dust, extinction - Galaxy: center - stars: horizontal-branch

VizieR on-line data: <Available at CDS (J/A+A/511/A18): tablea2.dat AKs_fg6.fits>

Nomenclature: Table A.2: [SNM2010] NNNN (Nos 1-7738).

Status at CDS : All or part of tables of objects will not be ingested in SIMBAD.

Simbad objects: 1

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Number of rows : 1
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2023
#notes
1 GCIRS 16 Cl* 17 45 40.0 -29 00 28           ~ 341 0

Query : 2010A&A...511A..18S

Basic data :
GCIRS 16 -- Cluster of Stars
Origin of the objects types :

(Ref) Object type as listed in the reference "Ref"
(acronym) Object type linked to the acronym according to the original reference
() Anterior to 2007, before we can link the objet type to a reference, or given by the CDS team in some particular cases

Other object types:
Cl* (2013A&A,[BDB2003]), IR (BHA,GCIRS)
Syntax of coordinates is : "ra dec (wtype) [error ellipse] quality bibcode" :
  • ra dec : right ascension and declination (unit and frame defined according to your Output Options)
    Grey values are increasing the original precision due to the computation of frame transformations
  • (wtype) : wavelength class for the origin of the coordinates (Rad, mm, IR, Optical, UV, Xray, Gam)
  • [error ellipse] : measurement uncertainty, on (ra,dec) if the positional angle is 90 degrees, on (majaxis,minaxis) otherwise (in mas at defined epoch in the original catalogue),
    position angle (in degrees North celestial pole to East)
  • quality : flag of quality
    • E ≥ 10"
    • D : 1-10" (and some old data)
    • C : 0.1-1"
    • B : 0.01-0.1" + 2MASS, Tyc
    • A : VLBI, Hipparcos
  • bibcode : bibcode of the coordinates reference
ICRS coord. (ep=J2000) :
17 45 40.0 -29 00 28 [ ] E 2013A&A...560A..76M
Syntax of coordinates is : "ra dec (wtype) [error ellipse] quality bibcode" :
  • ra dec : right ascension and declination (unit and frame defined according to your Output Options)
    Grey values are increasing the original precision due to the computation of frame transformations
  • (wtype) : wavelength class for the origin of the coordinates (Rad, mm, IR, Optical, UV, Xray, Gam)
  • [error ellipse] : measurement uncertainty, on (ra,dec) if the positional angle is 90 degrees, on (majaxis,minaxis) otherwise (in mas at defined epoch in the original catalogue),
    position angle (in degrees North celestial pole to East)
  • quality : flag of quality
    • E ≥ 10"
    • D : 1-10" (and some old data)
    • C : 0.1-1"
    • B : 0.01-0.1" + 2MASS, Tyc
    • A : VLBI, Hipparcos
  • bibcode : bibcode of the coordinates reference
FK4 coord. (ep=B1950 eq=1950) :
17 42 29.3 -28 59 18 [ ]
Syntax of coordinates is : "ra dec (wtype) [error ellipse] quality bibcode" :
  • ra dec : right ascension and declination (unit and frame defined according to your Output Options)
    Grey values are increasing the original precision due to the computation of frame transformations
  • (wtype) : wavelength class for the origin of the coordinates (Rad, mm, IR, Optical, UV, Xray, Gam)
  • [error ellipse] : measurement uncertainty, on (ra,dec) if the positional angle is 90 degrees, on (majaxis,minaxis) otherwise (in mas at defined epoch in the original catalogue),
    position angle (in degrees North celestial pole to East)
  • quality : flag of quality
    • E ≥ 10"
    • D : 1-10" (and some old data)
    • C : 0.1-1"
    • B : 0.01-0.1" + 2MASS, Tyc
    • A : VLBI, Hipparcos
  • bibcode : bibcode of the coordinates reference
Gal coord. (ep=J2000) :
359.9442 -00.0460 [ ]
Syntax of angular size is : "maj-axis min-axis angle (wtype) quality bibcode"
  • maj-axis : major axis size (arc minutes)
  • min-axis : minor axis size (arc minutes)
  • angle : orientation angle (in degrees)
  • (wtype) : wavelength class for the origin of the angular size (Rad, mm, IR, Opt, UV, Xray, Gam)
  • quality : flag of quality of the angular size values ( A=best quality -> E=worst quality, {� } =unknown quality)
  • bibcode : bibcode of the angular size reference
Angular size (arcmin):
0.70 0.70 90 (~) D 2013A&A...560A..76M
SIMBAD within arcmin
', {sourceSize:12, color:'#30a090'})); aladin.on('objectClicked', function(object) { var objName=object.data.MAIN_ID; aladin.showPopup(object.ra,object.dec,'',''+ objName+''); });" title="Show Simbad objects"> Overlay Simbad points in this preview
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within arcsec The VizieR photometry tool allows for easy visualization of photometry points extracted around the Simbad position from photometry-enabled catalogues in VizieR.
The search radius has to be specified by the user. It is currently limited to a maximum of 30 arcsec. It depends mostly on the precision or quality of the coordinates (SIMBAD and VizieR catalogs), the resolution of the images from which the sources were extracted, source extent, and source crowding.
Suggestions are: crowded field: 0.5 to 1.5 arcsec, 3 arcsec otherwise; uncertain coordinates (SIMBAD quality E or coordinates without reference): 5 to 30 arsec (risky!).
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The link on the acronym of the identifiers give access to the information for this acronym in the dictionary of nomenclature.
Identifiers (12) :
An access of full data is available using the icon Vizier near the identifier of the catalogue

NAME Gal Center IRS 16 NAME Sgr A IRS 16 NAME Gal Center Cluster NAME Central Cluster in Gal Center
BHA 16 NAME Sgr A* (IR) Complex NAME Galactic Center Cluster [BDB2003] G359.94-00.04
GCIRS 16 NAME Sgr A* Cluster NAME Galactic Center IRS 16

References (341 between 1850 and 2023) (Total 341)
Simbad bibliographic survey began in 1850 for stars (at least bright stars) and in 1983 for all other objects (outside the solar system).
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2022.11.29-16:53:37

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