J/ApJ/892/91 UKIRT NIR and Spitzer MIR phot. in NGC 6822 (Hirschauer+, 2020)
Dusty stellar birth and death in the metal-poor galaxy NGC 6822.
Hirschauer A.S., Gray L., Meixner M., Jones O.C., Srinivasan S.,
Boyer M.L., Sargent B.A.
<Astrophys. J., 892, 91-91 (2020)>
=2020ApJ...892...91H 2020ApJ...892...91H (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies, IR; Stars, giant; Photometry, infrared; YSOs
Keywords: Asymptotic giant branch stars; Young stellar objects
Dwarf irregular galaxies; Infrared photometry; Star-forming regions
Abstract:
The nearby (∼500kpc) metal-poor ([Fe/H]~-1.2; Z∼30%Z☉)
star-forming galaxy NGC 6822 has a metallicity similar to systems at
the epoch of peak star formation. Through identification and study of
dusty and dust-producing stars, it is therefore a useful laboratory to
shed light on the dust life cycle in the early universe. We present a
catalog of sources combining near- and mid-IR photometry from the
United Kingdom Infrared Telescope (J, H, and K) and the Spitzer Space
Telescope (IRAC 3.6, 4.5, 5.8, and 8.0µm and MIPS 24µm). This
catalog is employed to identify dusty and evolved stars in NGC 6822
utilizing three color-magnitude diagrams (CMDs). With diagnostic CMDs
covering a wavelength range spanning the near- and mid-IR, we develop
color cuts using kernel density estimate (KDE) techniques to identify
dust-producing evolved stars, including red supergiant (RSG) and
thermally pulsing asymptotic giant branch (TP-AGB) star candidates. In
total, we report 1292 RSG candidates, 1050 oxygen-rich AGB star
candidates, and 560 carbon-rich AGB star candidates with high
confidence in NGC 6822. Our analysis of the AGB stars suggests a
robust population inhabiting the central stellar bar of the galaxy,
with a measured global stellar metallicity of [Fe/H]=-1.286±0.095,
consistent with previous studies. In addition, we identify 277 young
stellar object (YSO) candidates. The detection of a large number of
YSO candidates within a centrally located, compact cluster reveals the
existence of an embedded, high-mass star formation region that has
eluded previous detailed study. Spitzer I appears to be younger and
more active than the other prominent star-forming regions in the
galaxy.
Description:
This project utilized archival photometric data of NGC 6822 in the
near- and mid-IR.
From the study of Sibbons+ (2012, J/A+A/540/A135), ground-based J, H,
and K photometry have been adopted from the Wide Field CAMera (WFCAM)
on the 3.8m UKIRT.
Spitzer photometry ranging from 3.6 to 24um were adopted from
Khan+ (2015, J/ApJS/219/42).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 249 30745 The master catalog
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See also:
J/AJ/121/2020 : CTIO and WFPC2 photometry in NGC 6822 (Bianchi+, 2001)
J/ApJ/851/152 : DUSTiNGS. IV. AGB spectral types with HST (Boyer+, 2017)
J/AJ/142/103 : Cool evolved stars in SAGE-SMC and SAGE-LMC (Boyer+, 2011)
J/ApJ/800/51 : DUSTiNGS II. Metal-poor dusty AGB stars (Boyer+, 2015)
J/ApJ/810/116 : S-type AGB stars in SMC (Boyer+, 2015)
J/ApJS/216/10 : DUSTiNGS. I. The Good Source Catalog (Boyer+, 2015)
J/A+A/542/A66 : YSOs in 9 LMC star forming regions (Carlson+, 2012)
J/A+A/429/837 : IJKs photometry of late-type stars in NGC 6822 (Cioni+, 2005)
J/A+A/448/181 : IR colours of AGB and post-AGB stars (Groenewegen+, 2006)
J/A+A/495/447 : PN and HII regions in NGC6822 (Hernandez-Martinez+, 2009)
J/ApJS/162/49 : UBV imaging of irregular galaxies (Hunter+, 2006)
J/MNRAS/470/3250 : SAGE LMC point-sources classification (Jones+, 2017)
J/ApJ/811/145 : LMC & SMC evolved stars detected with Herschel (Jones+, 2015)
J/ApJ/841/15 : Synthetic JWST/MIRI fluxes and magnitudes (Jones+, 2017)
J/ApJ/854/117 : NIR stellar populations in Sextans A and Leo A (Jones+, 2018)
J/A+A/537/A108 : NGC 6822 AGB spectroscopic catalogue (Kacharov+, 2012)
J/A+A/454/717 : NIR photometry of C and AGB stars in NGC 6822 (Kang+, 2006)
J/PASP/122/683 : SAGE-Spec Spitzer legacy program (Kemper+, 2010)
J/ApJ/715/1094 : Census of self-obscured massive stars (Khan+, 2010)
J/ApJS/219/42 : Spitzer point source catalogs in 7 nearby gal. (Khan+, 2015)
J/ApJ/834/9 : Spectroscopy obs. of LeoA, Aqr & Sgr dwarf gal. (Kirby+, 2017)
J/AJ/123/832 : C star population in NGC 6822 (Letarte+, 2002)
J/ApJ/858/11 : NIR tip of RGB. I. JHK photometry of IC1613 (Madore+, 2018)
J/AJ/109/173 : BVR photometry of NGC 6822 (Marconi+ 1995)
J/AJ/110/2715 : UBV photometry in NGC 6822, M31 and M33 (Massey+ 1995)
J/AJ/133/2393 : UBVRI phot. in 7 Local Group dwarfs galaxies (Massey+, 2007)
J/AJ/144/4 : Dwarf galaxies in the Local Group (McConnachie+, 2012)
J/AJ/146/62 : HERschel HERITAGE in Magellanic Clouds (Meixner+, 2013)
J/AJ/132/2268 : SAGE calibration stars (Meixner+, 2006)
J/AJ/138/1203 : Star formation regions in nearby dwarf gal. (Melena+, 2009)
J/ApJ/753/71 : Mass-loss return from LMC evolved stars. VI. (Riebel+, 2012)
J/MNRAS/451/3504 : Classification of IRS sources in the SMC (Ruffle+, 2015)
J/ApJ/744/20 : S4MC project: 6 star forming regions PAHs (Sandstrom+, 2012)
J/ApJ/835/278 : Molecular clouds in the dwarf galaxy NGC6822 (Schruba+, 2017)
J/ApJ/699/150 : Spectral classifications of Massive YSOs in LMC (Seale+, 2009)
J/AJ/148/124 : Herschel key program Heritage (Seale+, 2014)
J/ApJ/778/15 : SAGE-SMC III. Young stellar objects (Sewilo+, 2013)
J/A+A/540/A135 : AGB population of NGC 6822 (Sibbons+, 2012)
J/A+A/574/A102 : AGB candidates in NGC 6822 (Sibbons+, 2015)
J/MNRAS/457/2814 : SAGE SMC evolved stars candidates (Srinivasan+, 2016)
J/MNRAS/428/2216 : JHKs photometry of AGB stars in NGC 6822 (Whitelock+, 2013)
J/AJ/136/18 : LMC SAGE. New candidate YSOs (Whitney+, 2008)
J/MNRAS/411/1597 : LMC point source classification in SAGE-Spec (Woods+, 2011)
J/MNRAS/400/1413 : Near-IR spectra of extremely red AGB stars (Wright+, 2009)
J/A+A/616/A175 : Red supergiant stars in the LMC. II. (Yang+, 2018)
J/A+A/629/A91 : A source catalog for the SMC (Yang+, 2019)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 5 I5 --- Seq MIR unique identifier
(<[KSK2015] JDDD.ddddd+DD.ddddd> in Simbad)
7- 15 F9.5 deg RAdeg [296.02/296.46] MIR right ascension (J2000)
17- 25 F9.5 deg DEdeg [-14.98/-14.62] MIR declination (J2000)
27- 31 F5.2 mag 3.6mag [9/20.3] Spitzer/IRAC 3.6um band magnitude
33- 36 F4.2 mag e_3.6mag [0.02/0.3] Uncertainty in 3.6mag
38- 42 F5.2 mag 4.5mag [8.9/19.7] Spitzer/IRAC 4.5um band magnitude
44- 47 F4.2 mag e_4.5mag [0.02/0.3] Uncertainty in 4.5mag
49- 56 F8.2 mag 5.8mag [8.4/18.3]?=-9999 Spitzer/IRAC 5.8um band
magnitude
58- 65 F8.2 mag e_5.8mag [0.01/0.3]?=-9999 Uncertainty in 5.8mag
67- 74 F8.2 mag 8.0mag [8.5/17.7]?=-9999 Spitzer/IRAC 8.0um band
magnitude
76- 83 F8.2 mag e_8.0mag [0.01/0.3]?=-9999 Uncertainty in 8.0mag
85- 92 F8.2 mag 24mag [2.9/15.8]?=-9999 Spitzer/MIPS 24um band
magnitude
94-101 F8.2 mag e_24mag [0.01/0.3]?=-9999 Uncertainty in 24mag
103-108 I6 --- NIR-ID [93314/141942]?=-9999 NIR unique identifier
(<[SRC2012] DDD.dddddd+DD.dddddd> in Simbad)(1)
110-121 F12.6 deg RANdeg ?=-9999 NIR right ascension (J2000) (1)
123-134 F12.6 deg DENdeg ?=-9999 NIR declination (J2000) (1)
136-150 F15.9 arcsec Sep [0.005/1]?=-9999 Distance to nearest-neighbor
near-infrared source
152-160 F9.3 mag Jmag [10.6/27.3]?=-9999 Apparent UKIRT/WFCAM J band
magnitude (1)(2)
162-170 F9.3 mag e_Jmag [0.001/6]?=-9999 Uncertainty in Jmag
172-180 F9.3 mag Hmag [10.7/27.7]?=-9999 Apparent UKIRT/WFCAM H band
magnitude (1)(2)
182-190 F9.3 mag e_Hmag [0.001/7]?=-9999 Uncertainty in Hmag
192-200 F9.3 mag Kmag [9.2/19.4]?=-9999 Apparent UKIRT/WFCAM K band
magnitude (1)(2)
202-210 F9.3 mag e_Kmag [0.001/0.4]?=-9999 Uncertainty in Kmag
212-216 A5 --- AGB AGB classification (2)(3)
218-222 I5 --- CMD1 [1/5]?=-9999 Numerical Region Categorization
for CMD 1: K vs. J-K (4)
224-228 I5 --- CMD2 [1/5]?=-9999 Numerical Region Categorization
for CMD 2: [3.6] vs J-[3.6] (4)
230-234 I5 --- CMD3 [1/6]?=-9999 Numerical Region Categorization
for CMD 3: [8.0] vs [3.6]-[8.0] (4)
236-249 A14 --- Class Final type classification (5)
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Note (1): For nearest-neighbor near-infrared source.
Note (2): JHK photometry adopted from Sibbons+ (2012, J/A+A/540/A135)
is presented in the WFCAM instrumental system; equations to convert to
the 2MASS system are given in Hodgkin+ (2009MNRAS.394..675H 2009MNRAS.394..675H).
Note (3): Classification as follows:
M = Oxygen-rich candidate (1099 occurrences)
C = Carbon-rich candidate (636 occurrences)
-9999 = unclassified (29010 occurrences)
Note (4): CMD region code (see Section 3.2) as follows:
1 = foreground main sequence (MS) stars
2 = red supergiant (RSG) candidates
3 = O-rich AGB star candidates
4 = C-rich AGB star candidates
5 = dust-enshrouded AGB star and YSO candidates
6 = background galaxies
Note (5): Classification as follows:
Galaxy = 13765 occurrences
Unclassifiable = 9706 occurrences
Unclassed! = 1660 occurrences
O-rich = 2583 occurrences
O-rich? = 124 occurrences
C-rich = 563 occurrences
C-rich? = 25 occurrences
Star = 1911 occurrences
Star? = 20 occurrences
YSO = 302 occurrences
YSODusty? = 9 occurrences
YSOC-rich? = 2 occurrences
Dusty? = 78 occurrences
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 11-Aug-2021