J/ApJ/754/30 VISTA IR photometry of σ Ori cluster (Pena Ramirez+, 2012)
New isolated planetary-mass objects and the stellar and substellar mass
function of the σ Orionis cluster.
Pena Ramirez K., Bejar V.J.S., Zapatero Osorio M.R., Petr-Gotzens M.G.,
Martin E.L.
<Astrophys. J., 754, 30 (2012)>
=2012ApJ...754...30P 2012ApJ...754...30P
ADC_Keywords: Photometry, infrared ; Clusters, open ; Surveys
Keywords: brown dwarfs; circumstellar matter; infrared: stars;
open clusters and associations: individual: sig Orionis;
stars: low-mass; stars: luminosity function, mass function
Abstract:
We report on our analysis of the VISTA Orion ZY JHKs photometric
data (completeness magnitudes of Z=22.6 and J=21.0 mag) focusing on a
circular area of 2798.4arcmin2 around the young σ Orionis star
cluster (∼3Myr, ∼352pc, and solar metallicity). The combination of the
VISTA photometry with optical, WISE and Spitzer data allows us to
identify a total of 210 σ Orionis member candidates with masses
in the interval 0.25-0.004M☉, 23 of which are new planetary-mass
object findings. These discoveries double the number of cluster
planetary-mass candidates known so far. One object has colors
compatible with a T spectral type. The σ Orionis cluster harbors
about as many brown dwarfs (69, 0.072-0.012M☉) and
planetary-mass objects (37, 0.012-0.004M☉) as very low mass
stars (104, 0.25-0.072M☉). Based on Spitzer data, we derive a
disk frequency of ∼40% for very low mass stars, brown dwarfs, and
planetary-mass objects in σ Orionis. The radial density
distributions of these three mass intervals are alike: all are
spatially concentrated within an effective radius of 12' (1.2pc)
around the multiple star σ Ori, and no obvious segregation
between disk-bearing and diskless objects is observed.
Description:
Our survey of the σ Orionis cluster is based on the VISTA Orion
survey data (Petr-Gotzens et al. 2011Msngr.145...29P 2011Msngr.145...29P). This survey was
a dedicated imaging exploration of 30deg2 in the Orion Belt region,
including σ Orionis, carried out as part of the VISTA science
verification program. VISTA is a near-infrared survey facility
equipped with a wide-field, near-infrared camera (VIRCAM) and mounted
on a 4.2m telescope at ESO's Paranal Observatory. Observations of the
σ Orionis region (tile number 16 according to the nomenclature
of the VISTA Orion survey) were performed between 2009 October 20 and
October 28 employing the VISTA (Vega) system broadband filters ZY JHKs.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 164 145 Properties of σ Orionis candidate members
with youth features
table5.dat 206 145 Near- and mid-infrared photometry of σ Orionis
candidate members with youth features
table6.dat 206 58 *Near- and mid-infrared photometry of known
σ Orionis photometric candidates
table7.dat 110 58 *Information about known σ Orionis photometric
candidates
table8.dat 165 23 Near- and mid-infrared photometry of new
σ Orionis photometric candidates
refs.dat 107 42 References
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Note on table6.dat and table7.dat : All these 58 sources comply with our
ZJ criteria for photometric cluster membership.
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See also:
II/311 : WISE All-Sky Data Release (Cutri+ 2012)
II/319 : UKIDSS-DR9 GCS (LAS and DXS) Surveys (Lawrence+ 2012)
III/177 : H-alpha emission stars in the Orion region (Wiramihardja+ 1993)
J/ApJ/743/64 : Deep infrared photometry of σ Ori cluster (Bejar+, 2011)
J/A+A/525/A47 : U-band photometry in sigma Orionis region (Rigliaco+, 2011)
J/ApJS/191/389 : Photometric monitoring in σ Ori cluster (Cody+, 2010)
J/A+A/493/931 : MAD observations of σ Ori (Bouy+, 2009)
J/ApJ/688/362 : Disks around brown dwarfs in sig Ori cluster (Luhman+, 2008)
J/A+A/488/167 : Low-mass stars in σ Ori and λ Ori (Sacco+, 2008)
J/A+A/478/667 : The Mayrit catalogue (Caballero, 2008)
J/MNRAS/385/2210 : Spectroscopy around lam Ori and sig Ori (Maxted+, 2008)
J/MNRAS/375/1220 : BVI photometry of young stars in 10 clusters (Mayne+, 2007)
J/ApJ/662/1067 : Spitzer observations of sigma Orionis (Hernandez+, 2007)
J/A+A/446/501 : XMM observations of sigma Ori cluster (Franciosini+, 2006)
J/MNRAS/356/1583 : RV of sig Ori low-mass candidate members (Burningham+, 2005)
J/MNRAS/356/89 : sigma Ori low-mass stars (Kenyon+, 2005)
J/A+A/419/249 : RJHKs photometry of sigma Ori low-mass stars (Scholz+, 2004)
J/AN/325/705 : RIJHKs of low-mass stars in sigma Ori (Bejar+, 2004)
J/AJ/128/2316 : BVRIJHKs photometry in sigma Ori cluster (Sherry+, 2004)
Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 2 I2 h RAh Hour of right ascension (J2000)
4- 5 I2 min RAm Minute of right ascension (J2000)
7- 11 F5.2 s RAs Second of right ascension (J2000)
13 A1 --- DE- Sign of declination (J2000)
14- 15 I2 deg DEd Degree of declination (J2000)
17- 18 I2 arcmin DEm Arcminute of declination (J2000)
20- 23 F4.1 arcsec DEs Arcsecond of declination (J2000)
25- 41 A17 --- Feat Youth features (1)
43 A1 --- Env [c] Enveloppe (1)
45- 61 A17 --- IRe Infrared excess (G1)
63-142 A80 --- OName Other name(s)
144-164 A21 --- Ref Reference(s) (see refs.dat file)
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Note (1): Flag as follows:
RV = radial velocity consistent with the systemic cluster radial velocity;
Li = lithium absorption at 607.82nm;
g = spectroscopic evidence for a low-gravity atmosphere;
Halpha = strong, broad Hα emission likely related to accretion/jet
events;
d = presence of a disk.
c = object located in the ZJ eligible zone of cluster members according
to our photometric criteria.
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Byte-by-byte Description of file: table[56].dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 2 I2 h RAh Hour of right ascension (J2000)
4- 5 I2 min RAm Minute of right ascension (J2000)
7- 11 F5.2 s RAs Second of right ascension (J2000)
13 A1 --- DE- Sign of declination (J2000)
14- 15 I2 deg DEd Degree of declination (J2000)
17- 18 I2 arcmin DEm Arcminute of declination (J2000)
20- 23 F4.1 arcsec DEs Arcsecond of declination (J2000)
25- 26 A2 --- l_Zmag [≥ ] Limit flag on Zmag
28- 33 F6.3 mag Zmag [14/23.1] VISTA Z-band magnitude
35- 39 F5.3 mag e_Zmag [0.002/0.2]? Zmag uncertainty
41- 46 F6.3 mag Ymag [13.5/21.3] VISTA Y-band magnitude
48- 52 F5.3 mag e_Ymag [0.001/0.3] Ymag uncertainty
54- 59 F6.3 mag Jmag [13/20.4] VISTA J-band magnitude
61- 65 F5.3 mag e_Jmag [0.001/0.2] Jmag uncertainty
67- 68 A2 --- l_Hmag [≥ ] Limit flag on Hmag
70- 75 F6.3 mag Hmag [12.1/19.9] VISTA H-band magnitude
77- 81 F5.3 mag e_Hmag [0.001/0.3]? Hmag uncertainty
83- 84 A2 --- l_Ksmag [≥ ] Limit flag on Ksmag
86- 91 F6.3 mag Ksmag [11.6/18.9] VISTA Ks-band magnitude
93- 97 F5.3 mag e_Ksmag [0.002/0.3]? Ksmag uncertainty
99-104 F6.3 mag [3.6] [10.4/18.2]? Spitzer/IRAC 3.6um magnitude
106-110 F5.3 mag e_[3.6] [0.01/0.3]? [3.6] uncertainty
112-117 F6.3 mag [4.5] [9.8/17]? Spitzer/IRAC 4.5um magnitude
119-123 F5.3 mag e_[4.5] [0.02/0.3]? [4.5] uncertainty
125-126 A2 --- l_[5.8] [≥ ] Limit flag on [5.8]
128-133 F6.3 mag [5.8] [9.1/16.1]? Spitzer/IRAC 5.8um magnitude
135-139 F5.3 mag e_[5.8] [0.01/0.6]? [5.8] uncertainty
141-142 A2 --- l_[8.0] [≥ ] Limit flag on [8.0]
144-149 F6.3 mag [8.0] [8.4/15.2]? Spitzer/IRAC 8um magnitude
151-155 F5.3 mag e_[8.0] [0.02/0.6]? [8.0] uncertainty
157-162 F6.3 mag W1mag [10.7/16.9]? WISE W1 (3.4um) magnitude (2)
164-168 F5.3 mag e_W1mag [0.01/0.2]? W1mag uncertainty (2)
170-175 F6.3 mag W2mag [9.8/15.7]? WISE W2 (4.6um) magnitude (2)
177-181 F5.3 mag e_W2mag [0.01/0.2]? W2mag uncertainty (2)
183-188 F6.3 mag W3mag [7.6/12.7]? WISE W3 (12um) magnitude (2)
190-194 F5.3 mag e_W3mag [0.02/0.3]? W3mag uncertainty (2)
196-200 F5.3 mag W4mag [3/8.4]? WISE W4 (22um) magnitude (2)
202-206 F5.3 mag e_W4mag [0.04/0.3]? W4mag uncertainty (2)
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Note (2): No WISE photometry implies signal-to-noise ratio below 4.
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Byte-by-byte Description of file: table7.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 2 I2 h RAh Hour of right ascension (J2000)
4- 5 I2 min RAm Minute of right ascension (J2000)
7- 11 F5.2 s RAs Second of right ascension (J2000)
13 A1 --- DE- Sign of declination (J2000)
14- 15 I2 deg DEd Degree of declination (J2000)
17- 18 I2 arcmin DEm Arcminute of declination (J2000)
20- 23 F4.1 arcsec DEs Arcsecond of declination (J2000)
25- 44 A20 --- IRe Infrared excess (G1)
46- 89 A44 --- OName Other name(s)
91-110 A20 --- Ref Reference(s) (see refs.dat file)
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Byte-by-byte Description of file: table8.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 2 I2 h RAh Hour of right ascension (J2000)
4- 5 I2 min RAm Minute of right ascension (J2000)
7- 11 F5.2 s RAs Second of right ascension (J2000)
13 A1 --- DE- Sign of declination (J2000)
14- 15 I2 deg DEd Degree of declination (J2000)
17- 18 I2 arcmin DEm Arcminute of declination (J2000)
20- 23 F4.1 arcsec DEs Arcsecond of declination (J2000)
25 A1 --- n_SOri Note on source (1)
27- 32 F6.3 mag Zmag [20.4/23.2] VISTA Z-band magnitude
34- 38 F5.3 mag e_Zmag [0.05/0.5] Zmag uncertainty
40- 41 A2 --- l_Ymag [≥ ] Limit flag on Ymag
43- 48 F6.3 mag Ymag [19.2/21.8] VISTA Y-band magnitude
50- 54 F5.3 mag e_Ymag [0.03/0.4]? Ymag uncertainty
56- 61 F6.3 mag Jmag [18.2/20.5] VISTA J-band magnitude
63- 67 F5.3 mag e_Jmag [0.02/0.2] Jmag uncertainty
69- 74 F6.3 mag Hmag [17.6/19.6] VISTA H-band magnitude
76- 80 F5.3 mag e_Hmag [0.04/0.3] Hmag uncertainty
82- 83 A2 --- l_Ksmag [≥ ] Limit flag on Ksmag
85- 90 F6.3 mag Ksmag [17/19] VISTA Ks-band magnitude
92- 96 F5.3 mag e_Ksmag [0.06/0.3]? Ksmag uncertainty
98-103 F6.3 mag [3.6] [16.1/18.2]? Spitzer/IRAC 3.6um magnitude
105-109 F5.3 mag e_[3.6] [0.1/0.4]? [3.6] uncertainty
111-116 F6.3 mag [4.5] [15.8/17.5]? Spitzer/IRAC 4.5um magnitude
118-122 F5.3 mag e_[4.5] [0.1/0.4]? [4.5] uncertainty
124-125 A2 --- l_[5.8] [≥ ] Limit flag on [5.8]
127-130 F4.1 mag [5.8] [16.1]? Spitzer/IRAC 5.8um magnitude
132-133 A2 --- l_[8.0] [≥ ] Limit flag on [8.0]
135-138 F4.1 mag [8.0] [15.2]? Spitzer/IRAC 8um magnitude
140-144 A5 --- --- [S Ori]
146-162 A17 --- SOri Source name (JHHMMSS.s+DDMMSS;
<[BMZ2001] S Ori JHHMMSS.s+DDMMSS> in Simbad)
164-165 A2 --- IRe [Y N OL] Infrared excess (G1)
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Note (1): Flag as follows:
b = W1(3.4um)=16.800±0.138mag.
c = T-type candidate.
d = Found in the extended ZJ search.
e = W1(3.4um)=16.904±0.149mag; W2(4.6um)=16.008±0.222mag.
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Byte-by-byte Description of file: refs.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- Ref Reference code
4- 22 A19 --- BibCode Bibcode
24- 52 A29 --- Aut First author's name(s)
53-107 A55 --- Comm Comment
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Global notes:
Note (G1): Infrared flux excesses ("Y") based on Spitzer (4.5 and 8.0um) and
WISE (12.0um) data. No flux excesses are denoted with "N".
Objects off limits of the Spitzer images are indicated with "OL".
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History:
From electronic version of the journal
(End) Emmanuelle Perret [CDS] 26-Feb-2014