J/ApJ/470/864 JHKL photometry of the Galactic Center (Blum+, 1996)
JHKL photometry and the K-band luminosity function at the Galactic Center.
Blum R.D., Sellgren K., Depoy D.L.
<Astrophys. J. 470, 864 (1996)>
=1996ApJ...470..864B 1996ApJ...470..864B
ADC_Keywords: Associations, stellar ; Photometry, infrared ; Reddening
Keywords: dust, extinction - Galaxy: center - Galaxy: stellar content -
infrared: stars - stars: luminosity function, mass function
Abstract:
J, H, K, and L photometry for the stars in the central ∼2' (∼5pc) of
the Galaxy are presented. Using the observed J-H, H-K, and K-L colors
and assumed intrinsic colors, we determine the interstellar extinction
at 2.2mm (AK) for approximately 1100 individual stars. The mean AK
(=3.3mag) is similar to previous results, but we find that the
reddening is highly variable, and some stars are likely to be seen
through AK>6mag. The dereddened K-band luminosity function points to
a significantly brighter component to the stellar population (>1.5mag
at K) than found in the stellar population in Baade's window,
confirming previous work done at lower spatial resolution. The
observed flux of all Galactic center stars with estimated K0
(dereddened magnitude) =<7.0mag is ∼25% of the total in the 2'x2'
field.
The data were obtained in July 11-13 on the 4m telescope at the Cerro
Tololo Observatory (CTIO) using the Ohio State Infrared Imager qnd
Spectrometer (OSIRIS). Our observations confirm the recent finding
that several bright M stars in the Galactic center are variable. Our
photometry also establishes the near-infrared variability of the M1-2
supergiant, IRS 7.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 88 185 Galactic center observed photometry
notes.dat 80 43 Notes to table1.dat
table2.dat 83 12 Variable stars in the Galactic Center
table4.dat 78 159 Galactic Center reddening-corrected photometry
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See also:
J/A+A/368/835 : Soft X-ray sources in the GC region (Sidoli+, 2001)
J/A+A/373/608 : Early-type stars towards the GC. II. (Dufton+, 2001)
J/A+AS/92/43 : Radio Obs. of OH/IR stars close to GC (Lindqvist+ 1992)
J/A+AS/97/587 : JHK photometry of Galactic center stars (Ruelas-Mayorga+ 1993)
J/A+AS/128/35 : New Sample of OH/IR stars in GC (Sjouwerman+ 1998)
J/AJ/106/2291 : UBV photometry toward Galactic Center (Reed 1993)
J/ApJ/523/248 : Variable stars in the Galactic center (Ott+, 1999)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- [BSD96] Sequential number
4 A1 --- n_[BSD96] [*] *: variable star, in table2.dat file
6- 16 A11 --- Name Name (G1)
18- 23 F6.2 arcsec oRA Offset in right ascension from IRS 7 (2)
26- 31 F6.2 arcsec oDE Offset in declination from IRS 7 (2)
34- 38 F5.2 mag Kmag K magnitude (3)
40- 43 F4.2 mag e_Kmag rms uncertainty on Kmag
46- 49 F4.2 mag J-K ? J-K colour index (3)
51- 54 F4.2 mag e_J-K ? rms uncertainty on J-K
57- 60 F4.2 mag H-K ? H-K colour index (3)
62- 65 F4.2 mag e_H-K ? rms uncertainty on H-K
68- 71 F4.2 mag K-L ? K-L colour index (3)
73- 76 F4.2 mag e_K-L ? rms uncertainty on K-L
78- 89 A12 --- Notes Comma-separated notes, see file notes.dat
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Note (2): IRS 7: RA = 17 45 39.987 DE = -29 00 22.24 ICRS 2000.0
(Position from Simbad, ref: 1989IAUS..136..443Y 1989IAUS..136..443Y)
Note (3): All photometry is from our primary OSIRIS data set unless otherwise
noted. The OSIRIS magnitudes include both measurement and calibration
uncertainties. The DePoy & Sharp (1991AJ....101.1324D 1991AJ....101.1324D, hereafter DS91)
data include only measurement uncertainty; calibration uncertainty is
not included.
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Byte-by-byte Description of file: notes.dat
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Bytes Format Units Label Explanations
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1- 4 A4 --- Note Symbol used in table1
9- 80 A72 --- Text Text of note
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 7 A7 --- Name Star name (IRS 7, 9 and 12N)
9- 13 F5.2 mag Jmag ? J magnitude
15- 18 F4.2 mag e_Jmag ? rms uncertainty on Jmag
20- 24 F5.2 mag Hmag ? H magnitude
26- 29 F4.2 mag e_Hmag ? rms uncertainty on Hmag
31- 34 F4.2 mag Kmag ? K magnitude
36- 39 F4.2 mag e_Kmag ? rms uncertainty on Kmag
41- 44 I4 yr Obs.Y Observation date (year)
46- 52 A7 --- Obs.M Observation date (month/month)
54- 73 A20 --- Set Data set (1)
75- 83 A9 -- Filt Filters used to derive J, H, and K magnitudes (2)
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Note (1): Data set:
Becklin et al., 1978ApJ...220..831B 1978ApJ...220..831B
DS91: DePoy & Sharp, 1991AJ....101.1324D 1991AJ....101.1324D
DS91b: DS91 photometry is consistent with J, H, and K magnitudes of
IRS 7 being the same as for Becklin et al., 1978ApJ...220..831B 1978ApJ...220..831B;
see text.
Note (2): J, H, and K are broad-band filters.
KND is broad-band K with a 1% neutral density filter.
NBK is K magnitude derived from two narrow-band filters
(Δλ/λ=1%) near 2.2mm; see text.
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Table 3: Young stellar object (YSO) photometry
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Observed Reddened (Red) Reddened (Blue) Reference
YSO name K H-K K H-K K H-K
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CRL 2591 8.6 3.7 12.2 6.0 6.3 2.3 1976PASP...88..874M 1976PASP...88..874M
CRL 2059 8.7 2.6 12.3 4.9 8.2 2.3 1985ApJ...298..328S 1985ApJ...298..328S
CRL 490 9.8 2.6 13.4 4.9 9.3 2.3 1976PASP...88..874M 1976PASP...88..874M
CRL 989 9.9 2.6 13.5 4.9 9.4 2.3 1972ApJ...172L..55A 1972ApJ...172L..55A
W33A 10.6 2.7 14.2 5.0 9.9 2.3 1987A&A...181..378C 1987A&A...181..378C
S140/IRS 1 10.7 2.4 14.3 4.7 10.5 2.3 1989ApJ...346..212E 1989ApJ...346..212E
CRL 961 10.8 1.7 14.4 4.0 11.7 2.3 1985AJ.....90.1113C 1985AJ.....90.1113C
NGC 7538/IRS 9 10.9 5.8 14.5 8.1 5.3 2.3 1979MNRAS.188..463W 1979MNRAS.188..463W
Mon R2/IRS 3 11.2 3.0 14.8 5.3 10.0 2.3 1976ApJ...208..390B 1976ApJ...208..390B
BN 11.2 4.6 14.8 6.9 7.5 2.3 1967ApJ...147..799B 1967ApJ...147..799B
S255/IRS 1 11.6 2.2 15.2 4.5 11.7 2.3 1977ApJ...217..448E 1977ApJ...217..448E
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Notes: Observed: observed K magnitude, corrected to a Galactic center (GC)
distance of 8kpc, and observed H-K color of YSO. No correction has
been applied for either the reddening of the YSO or the extinction
toward the GC.
Reddened (Red): Predicted K magnitude and H-K color of YSO at the GC, if the
YSO is intrinsically red. This assumes the intrinsic H-K color of the
YSO equals its observed H-K color, and there is no correction to the
YSO for extinction in its surrounding molecular cloud. An average GC
extinction of AK=3.6mag and E(H-K)=2.3mag has been applied.
Reddened (Blue): Predicted K magnitude and H-K color of YSO at the GC, if the
YSO is intrinsically blue. This assumes the intrinsic color of the YSO
is H-K=0.0 and the observed H-K color of the YSO is used to correct
for extinction in its surrounding molecular cloud. An average GC
extinction of AK=3.6mag and E(H-K)=2.3mag has been applied.
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- [BSD96] Sequential number
5- 15 A11 --- Name Name (G1)
16 A1 --- n_Name [*] Individual note on IRS 10EL (1)
18- 21 F4.2 mag K0mag Dereddened K magnitude (2)
23- 26 F4.2 mag e_K0mag rms uncertainty on K0mag
29- 32 F4.2 mag AK Absorption in K band (3)
34- 37 F4.2 mag e_AK ? rms uncertainty on AK
40- 43 F4.2 mag (J-K)0 ? Dereddened J-K colour index (2)
45- 48 F4.2 mag e_(J-K)0 ? rms uncertainty on (J-K)0
51- 54 F4.2 mag (H-K)0 ? Dereddened H-K colour index (2)
56- 59 F4.2 mag e_(H-K)0 ? rms uncertainty on (H-K)0
61- 65 F5.2 mag (K-L)0 ? Dereddened K-L colour index (2)
67- 70 F4.2 mag e_(K-L)0 ? rms uncertainty on (K-L)0
72- 81 A10 --- Notes Notes (4)
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Note (1): See notes for Table 1. Since this star is variable and K and L were
observed at different times, it is possible that the observed K-L is
too red and AK overestimated. The source is probably quite red,
however, since it was not detected at H or J.
Note (2): Includes photometric uncertainty and uncertainty in derived AK.
K0 results from average of DS91 and OSIRIS K when these differed by
less than 0.2mag.
Note (3): Includes photometric uncertainty only. No uncertainty given for
the case of mean reddening (AK=3.58) or AK = lower limit; see
notes c and d. For the case of two or more observed colors, only
observed colors that fell within +0.5 mag of the reddening line were
used to determine AK; see text.
Note (4): Notes:
c: AK is an estimated lower limit resulting from H-K, where H is
taken as the limiting H magnitude (14.25); see text.
d: Mean AK adopted from stars with measured H-K only; see text.
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Global notes:
Note (G1): Names: Simbad nomenclature when different than the written names:
AF XXX: NAME AF XXX in Simbad
BSD WC9, F95, TAM He1: Tam GCHe1 in Simbad
IRS: , (Nos 2L, 6WB, 10EL, 12NB, 30B)
IRS "A" names are taken from Tamura et al. (1996ApJ...467..645T 1996ApJ...467..645T).
Label "B" refers to a (usually) fainter source very close to the
primary source. Earlier, lower resolution data likely included both
components as a single source.
F95 (not in Simbad) refers to sources observed by Figer (1995,
Ph. D. thesis, UCLA).
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History:
Prepared via OCR at CDS.
(End) James Marcout, Patricia Bauer [CDS] 25-Jun-2001