J/ApJ/813/42 O and B type stars in W3: first results (Kiminki+, 2015)
The O- and B-type stellar population in W3: beyond the high-density layer.
Kiminki M.M., Kim J.S., Bagley M.B., Sherry W.H., Rieke G.H.
<Astrophys. J., 813, 42 (2015)>
=2015ApJ...813...42K 2015ApJ...813...42K (SIMBAD/NED BibCode)
ADC_Keywords: Stars, early-type ; Photometry, VRI ; Spectroscopy ;
Spectral types ; Cross identifications
Keywords: dust, extinction; stars: early-type; stars: formation;
open clusters and associations: individual: "Westerhout 3";
stars: luminosity function, mass function
Abstract:
We present the first results from our survey of the star-forming
complex W3, combining VRI photometry with multiobject spectroscopy to
identify and characterize the high-mass stellar population across the
region. With 79 new spectral classifications, we bring the total
number of spectroscopically confirmed O- and B-type stars in W3 to
105. We find that the high-mass slope of the mass function in W3 is
consistent with a Salpeter IMF, and that the extinction toward the
region is best characterized by an RV of approximately 3.6. B-type
stars are found to be more widely dispersed across the W3 giant
molecular cloud (GMC) than previously realized: they are not confined
to the high-density layer (HDL) created by the expansion of the
neighboring W4 H ii region into the GMC. This broader B-type
population suggests that star formation in W3 began spontaneously up
to 8-10 Myr ago, although at a lower level than the more recent star
formation episodes in the HDL. In addition, we describe a method of
optimizing sky subtraction for fiber spectra in regions of strong and
spatially variable nebular emission.
Description:
We observed W3 with the 90Prime wide-field imager at the Steward
Observatory 2.3m Bok Telescope on 2005 October 7.
We targeted candidate members of W3 for spectroscopic follow-up with
the Hectospec multi-fiber spectrograph on the 6.5m MMT. Thirty-one
Hectospec fiber configurations were observed in queue mode over 27
nights from 2008 to 2012. Exposure times were chosen to achieve a
minimum signal-to-noise ratio (S/N) of 25 at 6500Å.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 128 91 Photometry and spectral types of candidate
O- and B-type stars in W3
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See also:
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
III/195 : Atlas of Optical Spectral Classification OB Stars (Walborn+ 1990)
J/A+A/561/A12 : W3 Main JHKs photometry (Bik+, 2014)
J/ApJS/213/34 : Velocities of Cygnus OB2 massive binaries (Kobulnicky+, 2014)
J/ApJS/213/1 : The MSFRs Omnibus X-ray Catalog (MOXC) (Townsley+, 2014)
J/other/Sci/337.444 : RV curves of Galactic massive O stars (Sana+, 2012)
J/ApJ/751/4 : Radial velocities of massive stars in Cyg OB2 (Kiminki+, 2012)
J/ApJ/743/39 : Spitzer obs. of W3 molecular cloud (Rivera-Ingraham+, 2011)
J/ApJS/196/18 : CO survey of galactic molecular clouds. II. (Bieging+, 2011)
J/ApJ/733/113 : IRAC observations of IC 1795 (Roccatagliata+, 2011)
J/ApJS/194/9 : X-ray star clusters in the Carina complex (Feigelson+, 2011)
J/ApJ/654/338 : Spitzer photometry in W3 molecular cloud (Ruch+, 2007)
J/A+A/457/637 : UBVJHK synthetic photom. of Galactic O stars (Martins+, 2006)
J/AJ/129/907 : New Ori OB1 members (Briceno+, 2005)
J/AJ/129/393 : UBV photometry in W3 (Oey+, 2005)
J/ApJ/454/151 : OB Associations of the Northern Milky Way (Massey+ 1995)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- Seq Identification number from this work
4- 5 I2 h RAh [2] Hour of Right Ascension (J2000)
7- 8 I2 min RAm [22/29] Minute of Right Ascension (J2000)
10- 14 F5.2 s RAs Second of Right Ascension (J2000)
16 A1 --- DE- [+] Sign of the Declination (J2000)
17- 18 I2 deg DEd [61/62] Degree of Declination (J2000)
20- 21 I2 arcmin DEm Arcminute of Declination (J2000)
23- 26 F4.1 arcsec DEs Arcsecond of Declination (J2000)
28- 32 A5 --- --- [2MASS]
34- 50 A17 --- 2MASS 2MASS based IAU Name (JHHMMSSss+DDMMSSs)
52- 65 A14 --- AltID Alternative identification (1)
67- 71 F5.2 mag Vmag [13.9/20.3]? Cousins/Bessell V magnitude
73- 76 F4.2 mag e_Vmag [0.03/0.09]? Uncertainty in Vmag
78- 82 F5.2 mag Rmag [13.2/18]? Cousins/Bessell R magnitude
84- 87 F4.2 mag e_Rmag [0.03/0.05]? Uncertainty in Rmag
89- 93 F5.2 mag Imag [12.4/16]? Cousins/Bessell I magnitude
95- 98 F4.2 mag e_Imag [0.03]? Uncertainty in Imag
100-103 F4.1 mag Av [2.4/12.2]? Magnitudes of extinction
in V for RV=3.6
105-107 F3.1 mag e_Av [0/0.6]? Uncertainty in Av
109-118 A10 --- SpT Spectroscopic classification (2)
120-128 A9 --- f_SpT Comments on spectral properties (3)
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Note (1): Alternate identification references
[OWK2005] = Oey et al. (2005, J/AJ/129/393);
[NFD2011] = Navarete et al. (2011AJ....142...67N 2011AJ....142...67N);
IRS = Named infrared source in W3 Main.
See Ojha et al. (2004ApJ...608..797O 2004ApJ...608..797O); Bik et al. (2012ApJ...744...87B 2012ApJ...744...87B)
Note (2): Spectroscopic classification derived in this work except:
ID 27: from Navarete et al. (2011AJ....142...67N 2011AJ....142...67N);
ID 30 & 31: from Bik et al. (2012ApJ...744...87B 2012ApJ...744...87B).
Note (3): Comments on spectral properties
e = H-alpha emission;
Pa = Paschen emission;
sh = shell features;
pec = peculiar metal line absorption;
I = WISE Class I source from Koenig et al. (2012ApJ...744..130K 2012ApJ...744..130K);
II = WISE Class II source from Koenig et al. (2012ApJ...744..130K 2012ApJ...744..130K)
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 11-Feb-2016