J/ApJ/718/810 Astrometry and Photometry in the Arches cluster (Stolte+, 2010)
Disks in the Arches cluster - Survival in a starburst environment.
Stolte A., Morris M.R., Ghez A.M., Do T., Lu J.R., Wright S.A., Ballard C.,
Mills E., Matthews K.
<Astrophys. J., 718, 810-831 (2010)>
=2010ApJ...718..810S 2010ApJ...718..810S
ADC_Keywords: Clusters, open ; Photometry, infrared ; Proper motions ; Stars, OB
Keywords: circumstellar matter - Galaxy: center -
open clusters and associations: individual (Arches) -
techniques: high angular resolution
Abstract:
Deep Keck/NIRC2 HK'L' observations of the Arches cluster near the
Galactic center reveal a significant population of near-infrared
excess sources. We combine the L'-band excess observations with
K'-band proper motions, which allow us to confirm cluster membership
of excess sources in a starburst cluster for the first time. The
robust removal of field contamination provides a reliable disk
fraction down to our completeness limit of H=19mag, or ∼5M☉ at
the distance of the Arches. Of the 24 identified sources with
K'-L'>2.0mag, 21 have reliable proper motion measurements, all of
which are proper motion members of the Arches cluster. VLT/SINFONI
K'-band spectroscopy of 3 excess sources reveals strong CO bandhead
emission, which we interpret as the signature of dense circumstellar
disks. The detection of strong disk emission from the Arches stars is
surprising in view of the high mass of the B-type main sequence host
stars of the disks and the intense starburst environment. We find a
disk fraction of 6%±2% among B-type stars in the Arches cluster. A
radial increase in the disk fraction from 3% to 10% suggests rapid
disk destruction in the immediate vicinity of numerous O-type stars in
the cluster core. A comparison between the Arches and other high- and
low-mass star-forming regions provides strong indication that disk
depletion is significantly more rapid in compact starburst clusters
than in moderate star-forming environments.
Description:
Five fields in the Arches cluster were observed in HK'L' with the
Keck II NIRC2 camera with the LGS-AO between 2006 May and 2008 July.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table4.dat 105 1413 Photometry and astrometry source list of the
Arches cluster
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See also:
J/A+A/501/563 : HKs photometry in the Arches cluster (Espinoza+, 2009)
J/MNRAS/371/38 : X-ray observations of the Galaxy center (Wang+, 2006)
J/ApJ/581/258 : Infrared photometry in the Arches Cluster (Figer+, 2002)
Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- ID Running identification number
(<[SMG2010b] NNNN> in Simbad)
6- 10 A5 --- Field Field name (1)
12- 18 F7.3 arcsec oRA Right Ascension offset (2)
20- 25 F6.3 arcsec oDE Declination offset (2)
27- 32 F6.4 arcsec e_oRA Positional uncertainty in dRA
34- 39 F6.4 arcsec e_oDE Positional uncertainty in dDE
41- 46 F6.3 mag Hmag Keck/NIRC2 H band magnitude
48- 52 F5.3 mag e_Hmag Uncertainty in Hmag
54- 59 F6.3 mag K'mag Keck/NIRC2 K' band magnitude
61- 65 F5.3 mag e_K'mag Uncertainty in K'mag
67- 73 F7.3 mag L'mag ?=-99.9 Keck/NIRC2 L' band magnitude
75- 81 F7.3 mag e_L'mag ?=-99.9 Uncertainty in L'mag
83- 86 F4.2 yr Dt Time baseline for proper motion measurement
88- 93 F6.3 mas/yr xpm Proper motion in x (pmRA*cos(DE))
95-100 F6.3 mas/yr ypm Proper motion in y (pmDE)
102-103 I2 --- Mm 2σ membership candidate (0=no, 1=yes) (3)
105 I1 --- Ex L band excess sources? (1=excess) (4)
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Note (1): Field are defined in table 1 as follows:
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Field R·A· Decl. dRA dDEC Tip-tilt Distance
(arcsec) Star to TTS
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core 17:45:50.540 -28:49:20.07 1.681 -2.190 425 10.369
east1 17:45:51.060 -28:49:20.07 8.620 -2.190 425 17.200
east2 17:45:51.740 -28:49:24.28 17.694 2.020 401 16.352
lead 17:45:50.960 -28:49:11.72 7.286 -10.540 425 18.998
halo 17:45:49.720 -28:49:16.87 -9.261 -5.390 425 5.603
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Positional offsets (dRA, dDEC), relative to the brightest source
in the cluster core, J174550.42-2849223 (see Figure 1); the cluster
center is located at 17:45:50.54-28:49:19.8.
Tip-tilt star identification numbers are given as extension from
GSC2.2:S222122222, located at 425: J17454978, J174522.3,
401: J174552.93-284928.13.
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Note (2): Positions are relative to the brightest K-band source in the
Arches core at 17:45:50.42-28:49:22.3 (J2000).
Note (3): Membership candidacy is defined from a 2-σ selection to
a gaussian fit to the proper motion distribution as follows:
1 = member candidate,
0 = non-member candidate,
-1 = unknown membership (no proper motion measurement).
Note (4): L-band excess sources as defined by their deviation from the
distribution of main sequence stars around the reddening path.
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 07-Jun-2012