J/MNRAS/439/2211 Post-AGB/RGB and YSOs in SMC (Kamath+, 2014)
Optically visible post-AGB/RGB stars and young stellar objects in the
Small Magellanic Cloud: candidate selection, spectral energy distributions and
spectroscopic examination.
Kamath D., Wood P.R., Van Winckel H.
<Mon. Not. R. Astron. Soc., 439, 2211-2270 (2014)>
=2014MNRAS.439.2211K 2014MNRAS.439.2211K
ADC_Keywords: Magellanic Clouds ; YSOs ; Stars, giant ; Photometry ;
Spectroscopy
Keywords: methods: observational - techniques: photometric -
techniques: spectroscopic - stars: AGB and post-AGB -
stars: fundamental parameters - Magellanic Clouds
Abstract:
We have carried out a search for optically visible post-asymptotic
giant branch (post-AGB) candidates in the Small Magellanic Cloud
(SMC). First, we used mid-IR observations from the Spitzer Space
Telescope to select optically visible candidates with excess mid-IR
flux and then we obtained low-resolution optical spectra for 801 of
the candidates. After removing poor-quality spectra and contaminants,
such as M-stars, C-stars, planetary nebulae, quasi-stellar objects and
background galaxies, we ended up with a final sample of 63
high-probability post-AGB/RGB candidates of A-F spectral type. From
the spectral observations, we estimated the stellar parameters:
effective temperature (Teff), surface gravity (logg) and
metallicity ([Fe/H]). We also estimated the reddening and deduced the
luminosity using the stellar parameters combined with photometry. For
the post-AGB/RGB candidates, we found that the metallicity
distribution peaks at [Fe/H]~-1.00dex. Based on a luminosity
criterion, 42 of these 63 sources were classified as post-red giant
branch (post-RGB) candidates and the remaining 21 as post-AGB
candidates. From the spectral energy distributions, we were able to
infer that 6 of the 63 post-AGB/RGB candidates have a surrounding
circumstellar shell suggesting that they are single stars, while 27 of
the post-AGB/RGB candidates have a surrounding disc, suggesting that
they lie in binary systems. For the remaining 30 post-AGB/RGB
candidates the nature of the circumstellar environment was unclear.
Variability is displayed by 38 of the 63 post-AGB/RGB candidates with
the most common variability types being the Population II Cepheids
(including RV-Tauri stars) and semiregular variables. This study has
also revealed a new RV Tauri star in the SMC, J005107.19-734133.3,
which shows signs of s-process enrichment. From the numbers of
post-AGB/RGB stars in the SMC, we were able to estimate evolutionary
rates. We find that the number of post-AGB and post-RGB candidates
that we have identified are in good agreement with the stellar
evolution models with some mass-loss in the post-AGB phase and a small
amount of re-accretion in the lower luminosity post-RGB phase. This
study also resulted in a new sample of 40 young stellar objects (YSOs)
of A-F spectral type. The 40 YSO candidates for which we could
estimate stellar parameters are luminous and of high mass
(∼3-10M☉). They lie on the cool side of the usually adopted
birthline in the HR-diagram. This line separates visually obscured
protostars from optically visible pre-main-sequence stars, meaning
that our YSO candidates have become optically visible in the region of
the HR diagram usually reserved for obscured protostars. Additionally,
we also identified a group of 63 objects whose spectra are dominated
by emission lines and in some cases, a significant UV continuum. These
objects are very likely to be either hot post-AGB/RGB candidates or
luminous YSOs.
Description:
In our survey, we used the SAGE-SMC catalogue (including the 2MASS
near-IR photometry) along with additional optical and mid-IR
photometry. Photometry in the U, V, B and I bands was added from the
Magellanic Clouds Photometric Survey (MCPS; Zaritsky et al., 2002,
Cat. J/AJ/123/855).
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 178 1194 Photometric data
table4.dat 120 38 The observational and stellar parameters for the
Q1 (first quality) post-AGB/RGB candidates
table5.dat 102 25 The observational and stellar parameters for the
Q2 (second quality) post-AGB/RGB candidates
table6.dat 123 27 The observational and stellar parameters for the
Q1 (first quality) YSO candidates
table7.dat 99 13 The observational and stellar parameters for the
Q2 (second quality) YSO candidates
tablea1.dat 138 63 The list of candidates with emission lines and
UV continuum
tableb1.dat 19 20 The M-stars in our sample
tableb2.dat 20 140 The C-stars in our sample
tableb3.dat 104 46 The new and previously known PN candidates in
our sample
spectra/* . 102 Individual FITS spectra for objects in tables 4-7
except J005908.99-710648.6 (in table4)
fig/* . 102 Individual PDF spectra for objects in tables 4-7
except J005908.99-710648.6 (in table4)
--------------------------------------------------------------------------------
See also:
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
II/305 : SAGE LMC and SMC IRAC Source Catalog (IPAC 2009)
II/311 : WISE All-Sky Data Release (Cutri+ 2012)
J/AJ/123/855 : Magellanic Clouds Photometric Survey (MCPS): the SMC
(Zaritsky+, 2002)
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 19 A19 --- Name Name (JHHMMSS.dd+DDMMSS.s)
21- 29 F9.6 deg RAdeg Right ascension (J2000)
31- 40 F10.6 deg DEdeg Declination (J2000)
42- 47 F6.3 mag Umag ?=99.999 U magnitude from MCPS (1)
49- 54 F6.3 mag Bmag ?=99.999 B magnitude from MCPS (1)
56- 61 F6.3 mag Vmag ?=99.999 V magnitude from MCPS (1)
63- 68 F6.3 mag Imag ?=99.999 I magnitude from MCPS (1)
(or DENIS if not in MCPS) (1)
70- 75 F6.3 mag Jmag ?=99.999 2MASS J magnitude
77- 82 F6.3 mag Hmag ?=99.999 2MASS H magnitude
84- 89 F6.3 mag Kmag ?=99.999 2MASS Ks magnitude
91- 96 F6.3 mag W1mag ?=99.999 WISE W1 magnitude (3.35µm)
98-103 F6.3 mag [3.6] ?=99.999 Spitzer/IRAC 3.6µm magnitude
105-110 F6.3 mag [4.5] ?=99.999 Spitzer/IRAC 4.5µm magnitude
112-117 F6.3 mag W2mag ?=99.999 WISE W2 magnitude (4.6µm)
119-124 F6.3 mag [5.8] ?=99.999 Spitzer/IRAC 5.8µm magnitude
126-131 F6.3 mag [8.0] ?=99.999 Spitzer/IRAC 8.0µm magnitude
133-138 F6.3 mag W3mag ?=99.999 WISE W3 magnitude (11.6µm)
140-145 F6.3 mag W4mag ?=99.999 WISE W4 magnitude (22.1µm)
147-152 F6.3 mag [24] ?=99.999 Spitzer/MIPS 24µm magnitude
154-159 F6.3 mag [70] ?=99.999 Spitzer/MIPS 70µm magnitude
161-166 F6.3 mag [160] ?=99.999 Spitzer/MIPS 160µm magnitude
168-172 I5 Lsun Lobs [93/42500] Observed luminosity
174-178 I5 K Teff [3500/19000] Effective photometric temperature
--------------------------------------------------------------------------------
Note (1): MCPS: Magellanic Clouds Photometric Survey (Zaritsky et al.,
2002AJ....123..855Z 2002AJ....123..855Z, Cat. J/AJ/123/855).
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table4.dat table5.dat table6.dat table7.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1 A1 --- n_Seq [AB] Code for [Fe/H] estimates (1)
3- 4 I2 --- Seq [1/63] Sequential number
6- 24 A19 --- Name Source name (JHHMMSS.ss+DDMMSS.s)
25 A1 --- n_Teff [bc] Teff was increased to estimate E(B-V) (2)
27- 31 I5 K Teff [3950/17000] Effective temperature
33- 36 F4.2 [cm/s2] logg [0/4] Surface gravity
38- 42 F5.2 [Sun] [Fe/H] [-2.3/-0.1] Metallicity
44- 47 F4.2 mag E(B-V) [0/1.2] Total redenning estimated (2)
49- 53 I5 Lsun Lobs [100/20000] Observed luminosity corrected for
foreground extinction
55- 59 I5 Lsun Lphot [75/22300] Photospheric luminosity
61- 65 A5 --- Type Estimated evolutionary status for post-AGB/RGB
candidates (p-RGB for a post-RGB star,
p-AGB for a post-AGB star)
67- 71 F5.1 km/s RV [40/300] Radial velocity
73- 76 F4.1 km/s e_RV [1/31] rms uncertainty on RV
78- 81 F4.2 Msun Mass [0.3/1]? Derived mass of the post-AGB/RGB
candidate (see Section 4)
83- 91 A9 --- SED SED comments (Disc, Shell or Uncertain)
93-123 A31 --- Cat Catalogue information (3)
--------------------------------------------------------------------------------
Note (1): Code as follows:
A = Candidates with [Fe/H] estimates from spectra
B = Candidates with assumed [Fe/H]=-1.00
Note (2): For some stars the estimated E(B-V) was negative which indicates that
the Teff estimated from the spectra is likely to be cooler than the actual
Teff of the star. For such stars, we estimated the E(B-V) using Teff values
increased by 250 and 500K. These stars are denoted using a suffix 'b' and 'c',
respectively.
Note (3): Throughout this contribution, positional cross-matching was
performed with catalogs from:
1 = Boyer et al. (2011AJ....142..103B 2011AJ....142..103B, Cat. J/AJ/142/103)
2 = De Smedt et al. (2012A&A...541A..67D 2012A&A...541A..67D)
3 = Volk et al. (2011ApJ...735..127V 2011ApJ...735..127V)
4 = Meyssonnier & Azzopardi (1993A&AS..102..451M 1993A&AS..102..451M, Cat. J/A+AS/102/451)
5 = Murphy & Bessell (2000MNRAS.311..741M 2000MNRAS.311..741M, Cat. J/MNRAS/311/741)
6 = Wilke et al. (2003A&A...401..873W 2003A&A...401..873W, Cat. J/A+A/401/873) (60um)
7 = Oliveira et al. (2013MNRAS.428.3001O 2013MNRAS.428.3001O)
8 = Loup et al. (1997A&AS..125..419L 1997A&AS..125..419L, J/A+AS/125/419)
9 = van Loon et al. (2010AJ....139.1553V 2010AJ....139.1553V)
10 = Wilke et al. (2003A&A...401..873W 2003A&A...401..873W, Cat. J/A+A/401/873) (25um)
= Bonanos et al. (2009AJ....138.1003B 2009AJ....138.1003B, Cat. J/AJ/138/1003)
= Groenewegen (2000A&A...363..901G 2000A&A...363..901G)
= Trams et al. (1999A&A...346..843T 1999A&A...346..843T)
= Kontizas et al. (2001A&A...369..932K 2001A&A...369..932K, Cat. J/A+A/369/932)
= Lagadec et al. (2007MNRAS.376.1270L 2007MNRAS.376.1270L)
= Sanduleak (1978ApJ...221..586S 1978ApJ...221..586S)
= Jacoby (1980ApJS...42....1J 1980ApJS...42....1J)
= Jacoby & De Marco (2002AJ....123..269J 2002AJ....123..269J, Cat. J/AJ/123/269)
= Morgan & Good (1985MNRAS.213..491M 1985MNRAS.213..491M)
= Morgan (1995A&AS..112..445M 1995A&AS..112..445M)
= Sanduleak & Pesch (1981PASP...93..431S 1981PASP...93..431S)
= Wilke et al. 2003 (J/A+A/401/873) at 12, 25, 60, 100 and 170um
= Simon et al. (2007ApJ...669..327S 2007ApJ...669..327S, Cat. J/ApJ/669/327).
The object types defined are;
C* = Carbon star
Em*, EmO = object with emission features
p-AGB = post-AGB star
[21] = 21um source
IRAS25 = IRAS source at 25um
IRAS60 = IRAS source at 60um
RGB = red giant branch star
RSG = red supergiant
FIR = far-IR object
x-AGB = dusty AGB star with superwind mass-loss
aO-AGB = anomalous O-rich AGB star
O-AGB = O-rich AGB
C-AGB = C-rich AGB
Y*O = Young stellar object
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Byte-by-byte Description of file: tablea1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1 A1 --- n_Name [Y] Y for Previously identified YSOs
3- 21 A19 --- Name Name (JHHMMSS.ss+DDMMSS.s)
23- 73 A51 --- ONames Previous identification (G1)
75- 79 I5 Lsun Lobs [200/42500] Observed luminosity (computed by
integrating under the flux distribution at
observed wavelengths)
81- 88 A8 --- Type Type (hot pA/R = hot post-AGB/RGB candidates)
90 A1 --- Ha [e0a] Hα 6563Å line information (G2)
91 A1 --- u_Ha [:] Uncertainty flag on Ha (G3)
93 A1 --- Hb [e0a] Hβ 4861Å line information (G2)
94 A1 --- u_Hb [:] Uncertainty flag on Hb (G3)
96 A1 --- Hg [e0a] Hγ 4341Å line information (G2)
97- 98 A2 --- u_Hg [:? ] Uncertainty flag on Hg (G3)
100 A1 --- [OIII]1 [e0a] [OIII] 4659Å line information (G2)
101 A1 --- u_[OIII]1 [:?] Uncertainty flag on [OIII]1 (G3)
103 A1 --- [OIII]2 [e0a] [OIII] 5007Å line information (G2)
104 A1 --- u_[OIII]2 [:?] Uncertainty flag on [OIII]2 (G3)
106 A1 --- HeI1 [e0a] HeI 4471Å line information (G2)
107 A1 --- u_HeI1 [:?] Uncertainty flag on HeI1 (G3)
109 A1 --- HeI2 [e0a?] HeI 5876Å line information (G2)
110 A1 --- u_HeI2 [:?] Uncertainty flag on HeI2 (G3)
112 A1 --- [SII]1 [e0a] [SII] 6717Å line information (G2)
113 A1 --- u_[SII]1 [:?] Uncertainty flag on [SII]1 (G3)
115 A1 --- [SII]2 [e0a] [SII] 6731Å line information (G2)
116 A1 --- u_[SII]2 [:?] Uncertainty flag on [SII]2 (G3)
118 A1 --- [NII]1 [e0a] [NII] 6548Å line information (G2)
119 A1 --- u_[NII]1 [:?] Uncertainty flag on [NII]1 (G3)
121 A1 --- [NII]2 [e0a] [NII] 6584Å line information (G2)
122 A1 --- u_[NII]2 [:?] Uncertainty flag on [NII]2 (G3)
124 A1 --- CaII1 [e0a] CaII 8498Å line information (G2)
125 A1 --- u_CaII1 [:?] Uncertainty flag on CaII1 (G3)
127 A1 --- CaII2 [e0a] CaII 8542Å line information (G2)
129 A1 --- CaII3 [e0a] CaII 8662Å line information (G2)
131 A1 --- Li [e0a] Li 6708Å line information (G2)
132 A1 --- u_Li [:?] Uncertainty flag on Li (G3)
134 A1 --- Ba [e0a] Ba 4554Å line information (G2)
136 A1 --- Pa [e0a] Pa line information (G2)
137-138 A2 --- u_Pa [:? ] Uncertainty flag on Pa (G3)
--------------------------------------------------------------------------------
Byte-by-byte Description of file: tableb1.dat tableb2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 19 A19 --- Name Name (JHHMMSS.ss+DDMMSS.s)
20 A1 --- n_Name [*] Note on Name (1)
--------------------------------------------------------------------------------
Note (1): J005705.78-741316.4 has been previously identified as a symbiotic
C-star by Belczynski et al. (2000A&AS..146..407B 2000A&AS..146..407B, Cat. J/A+AS/146/407) which
is confirmed by our low-resolution spectrum showing a photosphere of a C-star
with strong emission lines.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: tableb3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1 A1 --- f_Name [ui] Previously (u)ncatalogued or
(i)dentified PNe
3- 21 A19 --- Name Name (JHHMMSS.ss+DDMMSS.s)
22 A1 --- n_Name [*] Note on Name (1)
24- 52 A29 --- ONames Previous identification (G1)
54 A1 --- Ha [e0a] Hα 6563Å line information (G2)
55 A1 --- u_Ha [:?] Uncertainty flag on Ha (G3)
57 A1 --- Hb [e0a] Hβ 4861Å line information (G2)
58 A1 --- u_Hb [:?] Uncertainty flag on Hb (G3)
60 A1 --- Hg [e0a] Hγ 4341Å line information (G2)
61 A1 --- u_Hg [:?] Uncertainty flag on Hg (G3)
63 A1 --- [OIII]1 [e0a] [OIII] 4659Å line information (G2)
64 A1 --- u_[OIII]1 [:?] Uncertainty flag on [OIII]1 (G3)
66 A1 --- [OIII]2 [e0a] [OIII] 5007Å line information (G2)
67 A1 --- u_[OIII]2 [:?] Uncertainty flag on [OIII]2 (G3)
69 A1 --- HeI1 [e0a] HeI 4471Å line information (G2)
70 A1 --- u_HeI1 [:?] Uncertainty flag on HeI1 (G3)
72 A1 --- HeI2 [e0a] HeI 5876Å line information (G2)
73 A1 --- u_HeI2 [:?] Uncertainty flag on HeI2 (G3)
75 A1 --- [SII]1 [e0a] [SII] 6717Å line information (G2)
76 A1 --- u_[SII]1 [:?] Uncertainty flag on [SII]1 (G3)
78 A1 --- [SII]2 [e0a] [SII] 6731Å line information (G2)
79 A1 --- u_[SII]2 [:?] Uncertainty flag on [SII]2 (G3)
81 A1 --- [NII]1 [e0a] [NII] 6548Å line information (G2)
82 A1 --- u_[NII]1 [:?] Uncertainty flag on [NII]1 (G3)
84 A1 --- [NII]2 [e0a] [NII] 6584Å line information (G2)
85 A1 --- u_[NII]2 [:?] Uncertainty flag on [NII]2 (G3)
87 A1 --- CaII1 [e0a] CaII 8498Å line information (G2)
88 A1 --- u_CaII1 [:?] Uncertainty flag on CaII1 (G3)
90 A1 --- CaII2 [e0a] CaII 8542Å line information (G2)
91 A1 --- u_CaII2 [:?] Uncertainty flag on CaII2 (G3)
93 A1 --- CaII3 [e0a] CaII 8662Å line information (G2)
94 A1 --- u_CaII3 [:?] Uncertainty flag on CaII3 (G3)
96 A1 --- Li [e0a] Li 6708Å line information (G2)
97 A1 --- u_Li [:?] Uncertainty flag on Li (G3)
99 A1 --- Ba [e0a] Ba 4554Å line information (G2)
100 A1 --- u_Ba [:?] Uncertainty flag on Ba (G3)
102 A1 --- Pa [e0a] Pa line information (G2)
103-104 A2 --- u_Pa [:?] Uncertainty flag on Pa (G3)
--------------------------------------------------------------------------------
Note (1): * indicates that these objects are likely to be symbiotic stars as
their spectra show a photosphere of a cool star with a red continuum and
strong emission lines.
--------------------------------------------------------------------------------
Global notes:
Note (G1): Catalogue identifications:
Em*,EmO = object with emission features
PN = planetary nebula
G = Galaxy
HII = HII region
IR = Infrared source
I12 = IRAS12um source
I25 = IRAS25um source
I60 = IRAS60um source
I100 = IRAS100um source
YSO = Young stellar object
YSOd = Definite YSO
YSOp = Probable YSO
FIR = far-IR object (defined in Boyer et al. 2011, J/AJ/142/103)
RGB = red giant branch star (defined in Boyer et al. 2011, J/AJ/142/103)
RSG = red supergiant
x-AGB = dusty AGB star with superwind mass-loss
(defined in Boyer et al. 2011, J/AJ/142/103)
A positional cross-matching was performed with all the catalogues
mentioned in Table 4. The references, into brackets, are:
1 = Loup et al. (1997A&AS..125..419L 1997A&AS..125..419L, Cat. J/A+AS/125/419)
2 = Morgan & Good (1985MNRAS.213..491M 1985MNRAS.213..491M)
3 = Morgan (1995A&AS..112..445M 1995A&AS..112..445M)
4 = Wilke et al. (2003A&A...401..873W 2003A&A...401..873W, 25um, Cat. J/A+A/401/873)
5 = Wilke et al. (2003A&A...401..873W 2003A&A...401..873W, 100um, Cat. J/A+A/401/873)
6 = Boyer et al. (2011AJ....142..103B 2011AJ....142..103B, Cat. J/AJ/142/103)
7 = Wilke et al. (2003A&A...401..873W 2003A&A...401..873W, 60um, Cat. J/A+A/401/873)
8 = Meyssonnier & Azzopardi (1993A&AS..102..451M 1993A&AS..102..451M, Cat. J/A+AS/102/451)
9 = Murphy & Bessell (2000MNRAS.311..741M 2000MNRAS.311..741M, Cat. J/MNRAS/311/741)
10 = Lagadec et al. (2007MNRAS.376.1270L 2007MNRAS.376.1270L)
11 = Jacoby & De Marco (2002AJ....123..269J 2002AJ....123..269J, Cat. J/AJ/123/269)
12 = van Loon et al. (2010AJ....139.1553V 2010AJ....139.1553V)
13 = Volk et al. (2011ApJ...735..127V 2011ApJ...735..127V)
14 = Oliveira et al. (2013MNRAS.428.3001O 2013MNRAS.428.3001O)
16 = Jacoby (1980ApJS...42....1J 1980ApJS...42....1J)
17 = Sanduleak & Pesch (1981PASP...93..431S 1981PASP...93..431S)
18 = Simon et al. (2007ApJ...669..327S 2007ApJ...669..327S)
19 = Sanduleak (1978ApJ...221..586S 1978ApJ...221..586S)
Note (G2): Line information as follows:
a = absorption
e = emission
0 = feature is not observed
Note (G3): Line information uncertainty flag is (the low-resolution
could possibly affect the identification of a given line):
? = nature of the spectral line is uncertain
p = P-Cygni line profile
: = there is some line blending that has taken place or there is an
absorption line with an emission core or the line indicates signs
of strong winds and therefore mass-loss
--------------------------------------------------------------------------------
History:
* 18-Dec-2014: From electronic version of the journal
(with corrputed spectra)
* 05-Aug-2015: correct spectra supplied by Devika Kamath
(except for J005908.99-710648.6)
* 18-Aug-2015: missing spectrum and figure for J005908.99-710648.6
kindly supplied by Devika Kamath
(End) Patricia Vannier [CDS] 18-Dec-2014