J/AJ/150/100 WISE YSO candidates near σ and λ Ori (Koenig+, 2015)
Spectroscopic assessment of WISE-based young stellar object selection near
λ and σ Orionis.
Koenig X., Hillenbrand L.A., Padgett D.L., DeFelippis D.
<Astron. J., 150, 100 (2015)>
=2015AJ....150..100K 2015AJ....150..100K (SIMBAD/NED BibCode)
ADC_Keywords: Associations, stellar ; YSOs ; Photometry, infrared
Keywords: circumstellar matter - H II regions - infrared: stars -
stars: formation - stars: pre-main sequence
Abstract:
We have conducted a sensitive search down to the hydrogen burning
limit for unextincted stars over ∼200 square degrees around Lambda
Orionis and 20 square degrees around Sigma Orionis using the
methodology of Koenig & Leisawitz (2014ApJ...791..131K 2014ApJ...791..131K; K14). From
WISE and 2MASS data we identify 544 and 418 candidate young stellar
objects (YSOs) in the vicinity of λ and σ respectively.
Based on our followup spectroscopy for some candidates and the
existing literature for others, we found that ∼80% of the K14-selected
candidates are probable or likely members of the Orion star-forming
region. The yield from the photometric selection criteria shows that
WISE sources with KS-w3>1.5mag and KS between 10 and 12mag are
most likely to show spectroscopic signs of youth, while WISE sources
with KS-w3>4mag and Ks>12 were often active galactic nuclei when
followed up spectroscopically. The population of candidate YSOs traces
known areas of active star formation, with a few new "hot spots" of
activity near Lynds 1588 and 1589 and a more dispersed population of
YSOs in the northern half of the HII region bubble around σ and
ε Ori. A minimal spanning tree analysis of the two regions to
identify stellar groupings finds that roughly two-thirds of the YSO
candidates in each region belong to groups of 5 or more members. The
population of stars selected by WISE outside the MST groupings also
contains spectroscopically verified YSOs, with a local stellar density
as low as 0.5 stars per square degree.
Description:
We used the methodology of Koenig & Leisawitz (2014ApJ...791..131K 2014ApJ...791..131K)
that builds on the heritage of the work of Koenig et al.
(2012ApJ...744..130K 2012ApJ...744..130K), to identify a sample of 544 stars in λ
Orionis and 418 stars in σ Orionis that are candidate Young
Stellar Objects (YSOs).
Tables 3 and 4 present the entire WISE-2MASS derived catalogs of YSO
candidates for the σ and δ Orionis fields respectively.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 261 418 σ Orionis WISE YSO candidates
table4.dat 261 544 λ Orionis WISE YSO candidates
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See also:
B/mk : Catalogue of Stellar Spectral Classifications (Skiff, 2009-2016)
II/328 : AllWISE Data Release (Cutri+ 2013)
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
V/73 : Emission-Line Stars of the Orion Population (Herbig+ 1988)
J/MNRAS/435/1671 : SCUBA-2 850um survey in σ Ori (Williams+, 2013)
J/ApJ/754/30 : VISTA IR photometry of σ Ori (Pena Ramirez+, 2012)
J/ApJ/743/64 : Deep infrared photometry of σ Ori (Bejar+, 2011)
J/A+A/530/A150 : XMM observations of λ Ori (Franciosini+, 2011)
J/ApJS/191/389 : Photometric monitoring in σ Ori cluster (Cody+, 2010)
J/A+A/521/A45 : X-ray detections in the σ Ori (Caballero+, 2010)
J/A+A/493/931 : MAD observations of σ Ori (Bouy+, 2009)
J/ApJ/688/362 : Disks around brown dwarfs in σ Ori (Luhman+, 2008)
J/A+A/488/167 : σ Ori and λ Ori low-mass stars (Sacco+, 2008)
J/A+A/485/931 : Young stars and brown dwarfs in Ori OB1b (Caballero+, 2008)
J/MNRAS/385/2210 : Spectroscopy around lam Ori and sig Ori (Maxted+, 2008)
J/A+A/470/191 : Mid-IR and radio interferometry of S Ori (Wittkowski+, 2007)
J/A+A/446/501 : XMM observations of sigma Ori cluster (Franciosini+, 2006)
J/MNRAS/356/1583 : RV of Sigma Ori low-mass candidate members
(Burningham+, 2005)
J/MNRAS/356/89 : σ Ori low-mass stars (Kenyon+, 2005)
J/ApJ/610/1064 : Substellar population of λ Ori (Barrado+, 2004)
J/AN/325/705 : RIJHKs of low-mass stars in sigma Ori (Bejar+, 2004)
J/AJ/128/2316 : BVRIJHKs photometry in σ Ori cluster (Sherry+, 2004)
J/AJ/123/387 : VRI photometry of λ Ori SFR (Dolan+, 2002)
J/AJ/121/2124 : λ Ori PMS stars photometry (Dolan+, 2001)
J/AJ/118/2409 : VRI photometry of λ Ori PMS stars (Dolan+, 1999)
Byte-by-byte Description of file: table[34].dat
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Bytes Format Units Label Explanations
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1- 19 A19 --- WISE AllWISE catalog designation (JHHMMSS.ss+DDMMSS.s)
21- 29 F9.6 deg RAdeg Right Ascension in decimal degrees (J2000)
31- 39 F9.6 deg DEdeg Declination in decimal degrees (J2000)
41- 48 F8.3 mag Jmag [8.6/18.7]?=-100.000 2MASS J band magnitude
50- 57 F8.3 mag e_Jmag [0.01/0.3]?=-100.000 Uncertainty in Jmag
59- 66 F8.3 mag Hmag [7.9/16.5]?=-100.000 2MASS H band magnitude
68- 75 F8.3 mag e_Hmag [0.01/0.3]?=-100.000 Uncertainty in Hmag
77- 84 F8.3 mag Kmag [7.1/16.1]?=-100.000 2MASS Ks band magnitude
86- 93 F8.3 mag e_Kmag [0.01/0.2]?=-100.000 Uncertainty in Kmag
95-102 F8.3 mag W1mag [6.5/15.4]?=-100 WISE W1 3.4µm band magnitude
104-111 F8.3 mag e_W1mag [0.02/0.2]?=-100.000 Uncertainty in W1mag
113-120 F8.3 mag W2mag [5.6/13.2]?=-100 WISE W2 4.6µm band magnitude
122-129 F8.3 mag e_W2mag [0.01/0.2]?=-100.000 Uncertainty in W2mag
131-138 F8.3 mag W3mag [-4.5/12]?=-100.000 WISE W3 12µm band magnitude
140-147 F8.3 mag e_W3mag [0.01/0.5]?=-100.000 Uncertainty in W3mag
149-156 F8.3 mag W4mag [-1.7/9.2]?=-100 WISE W4 22µm band magnitude
158-165 F8.3 mag e_W4mag [0.01/0.6]?=-100.000 Uncertainty in W4mag
167-168 A2 --- Cl YSO classification (1)
170-174 F5.2 --- alpha [-3.51/2.4]? 2MASS-WISE spectral index α
176-182 F7.2 0.1nm EWHa [-181/16]?=999 Hα line equivalent width
(in Å) (2)
184-190 F7.2 0.1nm EWCaII [-47.1/3.1]?=999 CaII 854.2nm line equivalent
width (in Å) (2)
192 A1 --- Mm Likelihood of membership in the Orion star-forming
region (y=yes, m=maybe, n=no, -=unknown) (3)
194-206 A13 --- SpT Spectral type where available in the literature
208-261 A54 --- r_SpT Reference for SpT (4)
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Note (1): From the class scheme of Koenig & Leisawitz (2014ApJ...791..131K 2014ApJ...791..131K):
I = Class I/protostar;
II = Class II/T Tauri/Herbig AeBe star;
TD = Transition disk;
The flags 1-6 in Table4 were not documented by the authors.
Note (2): Negative equivalent width values denote line is in emission above the
continuum.
Note (3): We consulted Palomar DSS and SDSS images to determine whether sources
could be readily identified as galaxies, and also SIMBAD for previous
information in the literature regarding possible status as a contaminant or
a young star. In λ Ori, of 545 Koenig & Leisawitz
(2014ApJ...791..131K 2014ApJ...791..131K)-selected candidates, 349 have no
additional membership information from either the literature or our
spectra. Of the 196 with supplemental information beyond just the
photometry, we designate 149 as probable members (including 50 from our
spectra) and 26 (including 17 from our spectra) as possible members for a
confirmation rate of 76%-89%. In σ Ori, of 418 Koenig & Leisawitz
(2014ApJ...791..131K 2014ApJ...791..131K)-selected candidates, 147 have no additional
membership information from either the literature or our spectra. Of the
271 with supplemental information, 233 are probable members (including 38
from our spectra) and 33 (including 6 from our spectra) are possible
members, resulting in a confirmation rate of 86%-98%. Only 20 sources in
λ Ori and 4 in σ Ori are ruled out as galaxies or evolved
stars.
Note (4): Specific literature references given for objects with a spectral type.
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History:
From electronic version of the journal
(End) Prepared by [AAS]; Sylvain Guehenneux [CDS] 23-Oct-2015