J/ApJ/817/113 RIOTS4: spectroscopic survey of SMC field OB stars (Lamb+, 2016)
The Runaways and Isolated O-Type Star Spectroscopic Survey of the SMC (RIOTS4).
Lamb J.B., Oey M.S., Segura-Cox D.M., Graus A.S., Kiminki D.C.,
Golden-Marx J.B., Parker J.W.
<Astrophys. J., 817, 113 (2016)>
=2016ApJ...817..113L 2016ApJ...817..113L (SIMBAD/NED BibCode)
ADC_Keywords: Stars, early-type ; Radial velocities ; Spectral types ; Surveys
Keywords: binaries: spectroscopic; galaxies: stellar content; Magellanic Clouds;
stars: early-type; stars: emission-line, Be;
stars: fundamental parameters
Abstract:
We present the Runaways and Isolated O-Type Star Spectroscopic Survey
of the SMC (RIOTS4), a spatially complete survey of uniformly selected
field OB stars that covers the entire star-forming body of the Small
Magellanic Cloud (SMC). Using the IMACS (Inamori-Magellan Areal Camera
and Spectrograph) multislit spectrograph and MIKE (Magellan Inamori
Kyocera Echelle) echelle spectrograph on the Magellan telescopes, we
obtained spectra of 374 early-type field stars that are at least 28pc
from any other OB candidates. We also obtained spectra of an
additional 23 field stars in the SMC bar identified from slightly
different photometric criteria. Here, we present the observational
catalog of stars in the RIOTS4 survey, including spectral
classifications and radial velocities. For three multi-slit fields
covering 8% of our sample, we carried out monitoring observations over
9-16 epochs to study binarity, finding a spectroscopic, massive binary
frequency of at least ∼60% in this subsample. Classical Oe/Be stars
represent a large fraction of RIOTS4 (42%), occurring at much higher
frequency than in the Galaxy, consistent with expectation at low
metallicity. RIOTS4 confirmed a steep upper initial mass function in
the field, apparently caused by the inability of the most massive
stars to form in the smallest clusters. Our survey also yields
evidence for in situ field OB star formation, and properties of field
emission-line star populations, including sgB[e] stars and classical
Oe/Be stars. We also discuss the radial velocity distribution and its
relation to SMC kinematics and runaway stars. RIOTS4 presents a first
quantitative characterization of field OB stars in an external galaxy,
including the contributions of sparse, but normal, star formation;
runaway stars; and candidate isolated star formation.
Description:
Runaways and Isolated O-Type Star Spectroscopic Survey of the SMC
(RIOTS4) targets a spatially complete sample of 374 uniformly selected
candidate field OB stars in the SMC. Our targets are identified by Oey
et al. (2004, J/AJ/127/1632).
We observed the RIOTS4 survey targets over a five-year period from
2006 September to 2011 October using spectrographs on the Magellan
telescopes at Las Campanas Observatory.
The majority of our observations were obtained with the
Inamori-Magellan Areal Camera and Spectrograph (IMACS) in the f/4
multi-slit mode on the Magellan Baade telescope (slit widths of either
0.7" or 1.0", yielding spectral resolutions of R∼3700 and R∼2600,
respectively). With IMACS f/4 out of commission during our 2011
observations, we also operated IMACS in f/2 mode (we used either a
0.5" or 0.7" slit width, which yield spectral resolutions of R∼1000
and R∼1300, respectively).
The remaining targets were observed using the Magellan Inamori Kyocera
Echelle (MIKE) Spectrograph on the Magellan Clay telescope (R∼28000).
All MIKE observations occurred in 2010 November.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 81 374 Runaways and Isolated O-Type Star Spectroscopic
Survey of the SMC (RIOTS4) catalog
table2.dat 81 23 Additional UV-optically selected stars in the SMC bar
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See also:
II/236 : UBVR CCD survey of the Magellanic clouds (Massey, 2002)
III/195 : Atlas of Optical Spectral Classification OB Stars (Walborn+ 1990)
V/13 : Probable Members of the SMC (Azzopardi+ 1975, 1979)
III/23 : MK Classification for OB Stars (Lesh 1968)
J/A+A/562/A125 : OGLE-III SMC massive stars VI LCs (Kourniotis+, 2014)
J/ApJ/771/111 : SMC dusty OB stars. I. Optical spectroscopy (Sheets+, 2013)
J/ApJ/763/101 : Massive field OB stars in the SMC (Lamb+, 2013)
J/A+A/509/A11 : Ha emission-line objects in SMC clusters (Martayan+, 2010)
J/AJ/140/416 : IR photometry of massive stars in the SMC (Bonanos+, 2010)
J/AJ/137/3358 : Speckle interferometry of massive stars (Mason+, 2009)
J/ApJ/697/1695 : The Chandra survey of the SMC "Bar". II. (Antoniou+, 2009)
J/MNRAS/386/826 : Radial velocities of SMC massive stars (Evans+, 2008)
J/ApJ/652/458 : BVRHα photometry of cand. Be stars (Wisniewski+, 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/AJ/116/180 : Magellanic clouds ultraviolet observations (Parker+ 1998)
J/AcA/48/147 : OGLE SMC BVI photometry (Udalski+ 1998)
J/MNRAS/121/337 : Radcliffe Catalog of stars in Magellanic Clouds (Feast+ 1960)
Byte-by-byte Description of file: table[12].dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 5 I5 --- [M2002] [107/84544] Massey 2002 (Cat. II/236) identifier
(<[M2002] SMC NNNNN> in Simbad)
7- 11 F5.2 mag Bmag [12.4/15.3] Massey 2002 (Cat. II/236)
B band magnitude
13- 17 F5.2 mag Vmag [11.5/15.5] Massey 2002 (Cat. II/236)
V band magnitude
19- 23 F5.2 --- Q [-1.8/-0.8] The reddening-free QUBR parameter
(QUBR=(U-R)-1.396*(B-R))
25- 28 F4.2 mag Av [0/2.1] The V band extinction (1)
30- 48 A19 --- SpT MK spectral type
50 A1 --- f_SpT [f] Flag on SpT (2)
52- 54 I3 km/s RVel [44/395]? Radial velocity
56- 58 I3 km/s RVelHI [97/215]? The H I radial velocity (3)
60- 68 A9 --- Inst Instrument used in the observation (IMACS f/4;
and IMACS f/2 or MIKE for table 1)
70- 79 A10 "Y/M/D" Date ? UT date of the observation
81 A1 --- Flag [e] Multiple observation flag (2)
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Note (1): From Zaritsky et al. 2002, J/AJ/123/855
Note (2): Flag as follows:
e = Observed multiple times for binary monitoring; see Table 3.
f = From Massey (2012, II/236)
Note (3): From Stanimirovic et al. (1999MNRAS.302..417S 1999MNRAS.302..417S)
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 18-Apr-2016