J/ApJ/771/111 SMC dusty OB stars. I. Optical spectroscopy (Sheets+, 2013)
Dusty OB stars in the Small Magellanic Cloud.
I. Optical spectroscopy reveals predominantly main-sequence OB stars.
Sheets H.A., Bolatto A.D., van Loon J.TH., Sandstrom K., Simon J.D.,
Oliveira J.M., Barba R.H.
<Astrophys. J., 771, 111 (2013)>
=2013ApJ...771..111S 2013ApJ...771..111S
ADC_Keywords: Photometry, infrared ; Radial velocities ; Spectral types ;
Stars, OB ; Magellanic Clouds
Keywords: circumstellar matter; infrared: ISM; infrared: stars;
Magellanic Clouds; protoplanetary disks; stars: early-type
Abstract:
We present the results of optical spectroscopic follow-up of 125
candidate main sequence OB stars in the Small Magellanic Cloud (SMC)
that were originally identified in the S3MC infrared imaging survey
as showing an excess of emission at 24µm indicative of warm dust,
such as that associated with a transitional or debris disks. We use
these long-slit spectra to investigate the origin of the 24µm
emission and the nature of these stars. A possible explanation for the
observed 24µm excess, that these are emission line stars with dusty
excretion disks, is disproven for the majority of our sources. We find
that 88 of these objects are normal stars without line emission, with
spectral types mostly ranging from late-O to early-B; luminosity
classes from the literature for a sub-set of our sample indicate that
most are main-sequence stars. We further identify 17 emission-line
stars, 7 possible emission-line stars, and 5 other objects with
forbidden-line emission in our sample. We discover a new O6 Iaf star;
it exhibits strong HeII4686Å emission but relatively weak
NIII4640Å emission which we attribute to the lower nitrogen
abundance in the SMC. Two other objects are identified with planetary
nebulae, one with a young stellar object, and two with X-ray binaries.
To shed additional light on the nature of the observed 24µm excess
we use optical and infrared photometry to estimate the dust properties
of the objects with normal O and B star spectra and compare these
properties to those of a sample of hot spots in the Galactic
interstellar medium (ISM).
Description:
The optical spectra were obtained at the 3.5m New Technology Telescope
at the European Southern Observatory at La Silla, Chile in 2007
September (program 079.C-0485; PI: J. Th. van Loon), using the EMMI
instrument. The set-up provided wavelength coverage from ∼385 to 870nm
with R=570.
The photometry used to create the SEDs for each source is a
combination of B, V, and I data from the OGLE II survey (Udalski et
al. 1998, Cat. J/AcA/48/147) and the Magellanic Clouds Photometric
Survey (Zaritsky et al. 2002, Cat. J/AJ/123/855), J, H, and Ks from
the Two Micron All Sky Survey (2MASS; Skrutskie et al. 2006, Cat.
VII/233), and Spitzer Space Telescope data from both the original
S3MC (Bolatto et al. 2007, Cat. J/ApJ/655/212) survey and the
combined S3MC/SAGE-SMC catalogs (Gordon et al. 2011AJ....142..102G 2011AJ....142..102G),
making use of the IRAC and MIPS instruments.
File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 99 125 SMC dusty O and B stars: optical and 2MASS data
table2.dat 122 125 SMC dusty O and B stars: Spitzer data
table4.dat 93 125 SMC dusty O and B stars: spectral type,
radial velocity and identification
table5.dat 80 125 SMC dusty O and B stars: 4.5, 8, and 24um excesses
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See also:
III/274 : Galactic O-Star Spectroscopic Survey (Sota+, 2014)
II/305 : SAGE LMC and SMC IRAC Source Catalog (IPAC 2009)
VII/233 : The 2MASS Extended sources (IPAC/UMass, 2003-2006)
J/A+A/550/A107 : RV catalogue of O stars in 30 Doradus (Sana+, 2013)
J/ApJ/771/13 : UV-IR photometry of SMC stars (Lepo+, 2013)
J/other/Sci/337.444 : RV curves of Galactic massive O stars (Sana+, 2012)
J/AJ/140/416 : IR photometry of massive stars in the SMC (Bonanos+, 2010)
J/ApJ/712/925 : Transition circumstellar disks in Ophiuchus (Cieza+, 2010)
J/ApJS/187/228 : Hα profiles of Be stars (Silaj+, 2010)
J/PASJ/62/273 : AKARI SMC photometry (Ita+, 2010)
J/ApJ/705/1646 : Debris disks in Upper Sco (Carpenter+, 2009)
J/ApJ/700/1216 : Spectroscopy of Be stars in open clusters (McSwain+, 2009)
J/MNRAS/386/826 : Radial velocities of SMC massive stars (Evans+, 2008)
J/A+A/479/541 : VLT-FLAMES survey of massive stars (Hunter+, 2008)
J/A+A/462/683 : Velocities in SMC field of NGC 330 (Martayan+, 2007)
J/ApJ/655/212 : S3MC IRAC and MIPS photometry (Bolatto+, 2007)
J/ApJ/653/675 : Spitzer 24µm photometry of A dwarfs (Su+, 2006)
J/A+A/456/623 : VLT-FLAMES survey of massive stars (Evans+, 2006)
J/MNRAS/353/601 : 2dF survey of the Small Magellanic Cloud (Evans+, 2004)
J/AJ/127/1632 : UBVR(UIT) photometry of O and OB stars in SMC (Oey+, 2004)
J/AJ/123/855 : Magellanic Clouds Photometric Survey: SMC (Zaritsky+, 2002)
J/AcA/48/147 : OGLE SMC BVI photometry (Udalski+ 1998)
J/MNRAS/289/225 : SMC HI shells velocities (Staveley-Smith+ 1997)
J/ApJ/469/355 : Teff, B-V and BC relation (Flower, 1996)
J/A+AS/102/451 : Emission-line stars and PNe in the SMC (Meyssonnier+ 1993)
J/PASP/105/1127 : Distribution of Dust in Solar Neighborhood (Gaustad+ 1993)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1 A1 --- --- [B]
2- 4 I3 --- Seq [1/193] Identifier number
6- 25 A20 --- Name Name
27- 34 F8.5 deg RAdeg Right ascension in decimal degrees (J2000)
36- 44 F9.5 deg DEdeg Declination in decimal degrees (J2000)
46- 53 F8.2 uJy F(B) [644/12398]? OGLE-II B-band flux
55- 61 F7.2 uJy F(V) [945/8529] OGLE-II V-band flux
63- 69 F7.2 uJy F(I) [525/5186] OGLE-II I-band flux
71- 77 F7.2 uJy F(J) [353/5376]? 2MASS J-band flux
79 A1 --- r_F(J) [a] a: Original S3MC data point
81- 87 F7.2 uJy F(H) [253/5601]? 2MASS H-band flux
89 A1 --- r_F(H) [a] a: Original S3MC data point
91- 97 F7.2 uJy F(K) [168/7522]? 2MASS Ks-band flux
99 A1 --- r_F(K) [a] a: Original S3MC data point
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1 A1 --- --- [B]
2- 4 I3 --- Seq [1/193] Identifier number
6- 12 F7.2 uJy F3.6 [47/9138]? Spitzer/IRAC 3.6um flux
14 A1 --- r_F3.6 [b] b: Original S3MC data point
16- 21 F6.2 uJy e_F3.6 [1/467]? F3.6 uncertainty
23- 30 F8.2 uJy F4.5 [32/14030] Spitzer/IRAC 4.5um flux
32 A1 --- r_F4.5 [b] b: Original S3MC data point
34- 39 F6.2 uJy e_F4.5 [1/514] F4.5 uncertainty
41- 48 F8.2 uJy F5.8 [58/37120]? Spitzer/IRAC 5.8um flux
50 A1 --- r_F5.8 [b] b: Original S3MC data point
52- 58 F7.2 uJy e_F5.8 [5/1022]? F5.8 uncertainty
60- 68 F9.2 uJy F8.0 [45/100300]? Spitzer/IRAC 8.0um flux
70 A1 --- r_F8.0 [b] b: Original S3MC data point
72- 78 F7.2 uJy e_F8.0 [8/8321]? F8.0 uncertainty
80- 89 F10.2 uJy F24 [430/1632290] Spitzer/MIPS 24um flux (1)
91 A1 --- r_F24 [b] b: Original S3MC data point
93- 99 F7.2 uJy e_F24 [22/1265] F24 uncertainty (1)
101-111 F11.2 uJy F70 [41055/11107800]? Spitzer/MIPS 70um flux (1)
113 A1 --- r_F70 [b] b: Original S3MC data point
115-122 F8.2 uJy e_F70 [2123/36591]? F70 uncertainty (1)
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Note (1): Includes correction factor from MIPS to IRAC scale.
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1 A1 --- --- [B]
2- 4 I3 --- Seq [1/193] Identifier number
6- 10 A5 --- SpT This work MK spectral type (2)
12- 25 A14 --- SpTl MK spectral type(s) from literature
27- 29 I3 km/s RVl [103/250]? Radial velocity from literature
31- 32 I2 km/s e_RVl [3/17]? RVl uncertainty
34- 36 I3 km/s RVl2 ? Second radial velocity from literature
38- 39 I2 km/s e_RVl2 ? RVl2 uncertainty
41- 51 A11 --- Ref Reference(s) (3)
53- 55 I3 km/s RV [119/180]? HI radial velocity
57- 59 I3 km/s RV2 ? Second value of HI radial velocity
61- 63 I3 km/s RV2r ? Upper range of HI radial velocity
(implies RV2 is a lower range)
65- 67 I3 km/s RV3 ? Third value of HI radial velocity
69- 93 A25 --- Comm Comments
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Note (2): "Em" denotes objects with forbidden emission lines.
"OBe" denotes Be stars. "OBe?" denotes stars with unusually weak
Hα absorption. No spectral type information indicates that the
spectra were difficult to extract.
Note (3): References as follows:
A09 = Antoniou et al. (2009ApJ...707.1080A 2009ApJ...707.1080A);
C11 = Coe et al. (2011MNRAS.414.3281C 2011MNRAS.414.3281C);
E06 = Evans et al. (2006, J/A+A/456/623);
EH08 = Evans & Howarth (2008, J/MNRAS/386/826);
H08 = Hunter et al. (2008, J/A+A/479/541);
M07 = Martayan et al. (2007, J/A+A/462/683);
S = Simbad
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Byte-by-byte Description of file: table5.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1 A1 --- --- [B]
2- 4 I3 --- Seq [1/193] Identifier number
6 A1 --- f_Seq [b] Detected at 70um
8- 12 I5 uJy E4.5 [-101/13516] 4.5um excess
14- 16 I3 uJy e_E4.5 [3/517] E4.5 uncertainty
18- 22 F5.2 --- R4.5 [-0.4/36.3] 4.5um excess to expected
photosphere ratio
24- 27 F4.2 --- e_R4.5 [0.05/4] R4.5 uncertainty
29- 34 I6 uJy E8.0 [9/100122]? 8.0um excess
36- 39 I4 uJy e_E8.0 [9/8321]? E8.0 uncertainty
41- 45 F5.1 --- R8.0 [0.2/562]? 8.0um excess to expected
photosphere ratio
47- 50 F4.1 --- e_R8.0 [0.2/78]? R8.0 uncertainty
52- 58 I7 uJy E24 [425/1632264] 24um excess
60- 63 I4 uJy e_E24 [23/1265] E24 uncertainty
65- 69 I5 --- R24 [30/69138] 24um excess to expected
photosphere ratio
71- 74 I4 --- e_R24 [3/7623] R24 uncertainty
76- 80 F5.2 mag K-24 [3.3/11]? K-[24] color index
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History:
From electronic version of the journal
References:
Adams et al. Paper II. 2013ApJ...771..112A 2013ApJ...771..112A
(End) Emmanuelle Perret [CDS] 26-Jan-2015