J/ApJ/854/117 NIR stellar populations in Sextans A and Leo A (Jones+, 2018)
Near-infrared stellar populations in the metal-poor, dwarf irregular galaxies
Sextans A and Leo A.
Jones O.C., Maclay M.T., Boyer M.L., Meixner M., McDonald I., Meskhidze H.
<Astrophys. J., 854, 117 (2018)>
=2018ApJ...854..117J 2018ApJ...854..117J
ADC_Keywords: Galaxies, IR; Photometry, infrared; Photometry, UBVRI;
Effective temperatures; Stars, late-type
Keywords: circumstellar matter ; infrared: stars ; stars: late-type ;
stars: mass-loss
Abstract:
We present JHKs observations of the metal-poor ([Fe/H]<-1.40)
dwarf-irregular galaxies, Leo A and Sextans A, obtained with the WIYN
High-resolution Infrared Camera at Kitt Peak. Their near-IR stellar
populations are characterized by using a combination of
color-magnitude diagrams and by identifying long-period variable
stars. We detected red giant and asymptotic giant branch stars,
consistent with membership of the galaxy's intermediate-age
populations (2-8Gyr old). Matching our data to broadband optical and
mid-IR photometry, we determine luminosities, temperatures, and
dust-production rates (DPR) for each star. We identify 32 stars in
LeoA and 101 stars in Sextans A with a DPR>10-11M☉/yr,
confirming that metal-poor stars can form substantial amounts of dust.
We also find tentative evidence for oxygen-rich dust formation at low
metallicity, contradicting previous models that suggest oxygen-rich
dust production is inhibited in metal-poor environments. The total
rates of dust injection into the interstellar medium of Leo A and
Sextans A are (8.2±1.8)x10-9M☉/yr and
(6.2±0.2)x10-7M_☉/yr, respectively. The majority of this dust
is produced by a few very dusty evolved stars and does not vary
strongly with metallicity.
Description:
Ground-based observations of Sextans A and Leo A were obtained through
the broadband JHKs filters using the WIYN High-resolution Infrared
Camera (WHIRC) mounted on the 3.5m WIYN telescope at the Kitt Peak
National Observatory. The data were collected over four observing runs
over a period spanning from 2010 May to 2011 April.
In order to fully investigate the nature of the sources in our near-IR
catalog; we match our source catalog to all available photometric
catalogs for Leo A and Sextans A on a purely positional basis. The
ancillary data was obtained from the Hubble Space Telescope (HST;
Bianchi+ 2012, J/AJ/143/74 - UBVI filters), the Large Binocular
Telescope (LBT; Bellazzini+ 2014, J/A+A/566/A44 - g,r filters), the
Subaru Prime Focus Camera (Suprime; Stonkute+ 2014, J/ApJS/214/19 -
BVI filters), and the Spitzer Space Telescope
(Boyer+ 2009, J/ApJ/697/1993 ; 2015, J/ApJS/216/10 and 2015, J/ApJ/800/51).
Objects:
-------------------------------------------------------
RA (ICRS) DE Designation(s)
-------------------------------------------------------
10 11 00.5 -04 41 30 Sextans A = MCG-01-26-030
09 59 26.5 +30 44 47 Leo A = MCG+05-24-008
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 97 2 *Sextans A and Leo A parameters adopted in this work
table6.dat 129 779 Catalog of point sources for Leo A and Sextans A
table9.dat 41 443 Luminosities and dust-production rates of the 443
evolved stars
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Note on table1.dat: The fundamental parameters of the Sextans A and Leo A
galaxies are taken from McConnachie (2012, J/AJ/144/4), unless otherwise noted.
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See also:
VII/233 : The 2MASS Extended sources (IPAC/UMass, 2003-2006)
J/AJ/123/3154 : RV light curves of variable stars in Leo A (Dolphin+, 2002)
J/AJ/125/1261 : VI photometry of Sextans A Cepheids (Dolphin+, 2003)
J/A+A/442/281 : Late-type giants BVRIJHKL and Teff (Kucinskas+, 2005)
J/A+A/448/181 : IR colours of AGB and post-AGB stars (Groenewegen+, 2006)
J/A+A/503/913 : Synthetic spectrophotom. for C-rich giants (Aringer+, 2009)
J/ApJ/697/1993 : Spitzer study of AGB stars. III. (Boyer+, 2009)
J/AJ/137/3139 : LMC SAGE. New variable evolved stars and YSOs (Vijh+, 2009)
J/AJ/142/103 : Cool evolved stars in SAGE-SMC and SAGE-LMC (Boyer+, 2011)
J/A+A/532/A54 : GRAMS carbon-star model grid (Srinivasan+, 2011)
J/AJ/143/74 : HST photometry in 6 dwarf galaxies (Bianchi+, 2012)
J/MNRAS/427/3209 : Galactic and MC O-AGBs and RSGs stars (Jones+, 2012)
J/AJ/144/4 : Dwarf galaxies in the Local Group (McConnachie+, 2012)
J/MNRAS/427/2647 : Sgr dSph stars spectral classification (McDonald+, 2012)
J/ApJ/753/71 : Mass-loss return from LMC evolved stars. VI. (Riebel+, 2012)
J/A+A/540/A135 : AGB population of NGC 6822 (Sibbons+, 2012)
J/A+A/566/A44 : gr photometry of Sextans A and Sextans B (Bellazzini+, 2014)
J/MNRAS/440/631 : IR photometry of LMC O-rich evolved stars (Jones+, 2014)
J/ApJS/214/19 : Suprime-Cam wide-field photometry of Leo A (Stonkute+, 2014)
J/ApJ/789/147 : Star formation histories of LG dwarf galaxies (Weisz+, 2014)
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/ApJ/800/51 : DUSTiNGS II. Metal-poor dusty AGB stars (Boyer+, 2015)
J/MNRAS/457/2814 : SAGE SMC evolved stars candidates (Srinivasan+, 2016)
J/ApJ/834/9 : Spectroscopy of LeoA, Aqr & Sgr dwarf gal. (Kirby+, 2017)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 8 A8 --- Gal Galaxy name
10- 11 I2 h RAh Hour of right ascension (J2000)
13- 14 I2 min RAm Minute of right ascension (J2000)
16- 19 F4.1 s RAs Second of right ascension (J2000)
21 A1 --- DE- Sign of declination (J2000)
22- 23 I2 deg DEd Degree of declination (J2000)
25- 26 I2 arcmin DEm Arcminute of declination (J2000)
28- 29 I2 arcsec DEs Arcsecond of declination (J2000)
31- 34 I4 kpc Dist [789/1432] Distance
36- 37 I2 kpc e_Dist [44/53] Distance uncertainty
39- 43 F5.2 mag m-M [24.51/25.6] Distance modulus
45- 48 F4.2 mag e_m-M [0.1/0.2] m-M uncertainty
50- 54 F5.2 [-] [Fe/H] Metallicity
55 A1 --- f_[Fe/H] [b] b: Kirby et al. (2017, J/ApJ/834/9)
57- 60 F4.2 arcmin Rh [2.1/2.5] Half-light Radius
62- 63 I2 10+6Msun M* [6/44] Stellar Mass
65- 69 F5.3 mag E(B-V) [0.02/0.05] Color excess
71- 75 F5.2 mag ITRGB [20.5/21.8] Tip of the red giant branch
(TRGB) in I-band
77- 82 E6.2 Msun/yr DPRTot Best-fitting chemical type total
dust-production rate (from Table 10)
84- 89 E6.2 Msun/yr e_DPRTot DPRTot uncertainty
91- 97 E7.2 Msun/yr DPRMed Best-fitting chemical type median
dust-production rate (from Table 10)
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Byte-by-byte Description of file: table6.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 8 A8 --- Gal Galaxy identifier
10- 12 I3 --- ID [0/491] Point source identifier within Gal
14- 21 F8.4 deg RAdeg [149.8/152.8] Right Ascension (J2000)
23- 29 F7.4 deg DEdeg [-4.8/30.8] Declination (J2000)
31- 36 F6.2 mag Umag [18/23.2]?=-99.99 U band magnitude
38- 43 F6.2 mag Bmag [17.2/27.1]?=-99.99 B band magnitude
45- 50 F6.2 mag Vmag [16.4/26.6]?=-99.99 V band magnitude
52- 57 F6.2 mag Imag [16.7/24.6]?=-99.99 I band magnitude
59- 64 F6.2 mag Jmag [13.4/21]?=-99.99 WIYN/WHIRC J band magnitude
66- 71 F6.2 mag e_Jmag [0.04/0.1]?=-99.99 1σ uncertainty in Jmag
73- 78 F6.2 mag Hmag [13.3/19.8]?=-99.99 WIYN/WHIRC H band magnitude
80- 85 F6.2 mag e_Hmag [0.04/0.1]?=-99.99 1σ uncertainty in Hmag
87- 92 F6.2 mag Ksmag [13/19.2]?=-99.99 WIYN/WHIRC Ks band magnitude
94- 99 F6.2 mag e_Ksmag [0.04/0.1]?=-99.99 1σ uncertainty in Ksmag
101-106 F6.2 mag 3.6mag [12.9/20.7]?=-99.99 Spitzer/IRAC 3.6um magnitude
108-113 F6.2 mag 4.5mag [13/20.5]?=-99.99 Spitzer/IRAC 4.5um magnitude
115-120 F6.2 mag 5.8mag [13/18.4]?=-99.99 Spitzer/IRAC 5.8um magnitude
122-127 F6.2 mag 8.0mag [13/17.4]?=-99.99 Spitzer/IRAC 8.0um magnitude
129 I1 --- Var [0/1] Variable code (1=variable; 0=not variable)
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Byte-by-byte Description of file: table9.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 8 A8 --- Gal Galaxy identifier
10- 12 I3 --- ID [0/487] The WIYN High-resolution Infrared
Camera (WHIRC) identifier
14- 17 I4 K Teff [1200/7900]?=-99 Effective temperature
19- 23 F5.1 mag Mbol [-11.4/-2.2]?=-99 Bolometric magnitude
25- 31 E7.1 Msun/yr DPR [6.4e-14/5.5e-07] Dust Production Rate
33- 39 E7.1 Msun/yr e_DPR [1.1e-12/4.2e-09] 1σ uncertainty in DPR
41 A1 --- GRAMS GRAMS model chemistry (C=Carbon; O=Oxygen)
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 12-Nov-2018