J/ApJ/821/52 NIR survey of Spitzer YSOs in Orion Mol. Cloud (Kounkel+, 2016)
An HST survey for 100-1000au companions around young stellar objects in the
Orion molecular clouds: evidence for environmentally dependent multiplicity.
Kounkel M., Megeath S.T., Poteet C.A., Fischer W.J., Hartmann L.
<Astrophys. J., 821, 52-52 (2016)>
=2016ApJ...821...52K 2016ApJ...821...52K (SIMBAD/NED BibCode)
ADC_Keywords: YSOs ; Photometry, infrared ; Stars, double and multiple ;
Photometry, HST ; Surveys
Keywords: binaries: visual; infrared: stars; ISM: individual: Orion A;
stars: formation; stars: protostars
Abstract:
We present a near-infrared survey for the visual multiples in the
Orion molecular clouds region at separations between 100 and 1000au.
These data were acquired at 1.6um with the NICMOS and WFC3 cameras on
the Hubble Space Telescope. Additional photometry was obtained for
some of the sources at 2.05um with NICMOS and in the L' band with
NSFCAM2 on NASA's InfraRed Telescope Facility. Toward 129 protostars
and 197 pre-main-sequence stars with disks observed with WFC3, we
detect 21 and 28 candidate companions between the projected
separations of 100-1000au, of which less than 5 and 8, respectively,
are chance line-of-sight coincidences. The resulting companion
fraction (CF) after the correction for the line-of-sight contamination
is 14.4-1.3+1.1 for protostars and 12.5-0.8+1.2 for the
pre-main-sequence stars. These values are similar to those found for
main-sequence stars, suggesting that there is little variation in the
CF with evolution, although several observational biases may mask a
decrease in the CF from protostars to the main-sequence stars. After
segregating the sample into two populations based on the surrounding
surface density of young stellar objects, we find that the CF in the
high stellar density regions (ΣYSO>45pc-2) is approximately
50% higher than that found in the low stellar density regions
(ΣYSO<45pc-2). We interpret this as evidence for the
elevated formation of companions at 100-1000 au in the denser
environments of Orion. We discuss possible reasons for this elevated
formation.
Description:
As part of program GO 11548, 87 orbits of HST observations were
successfully executed with the NICMOS camera in 2008 August and
September. The remaining protostars in the target catalog were
observed in 126 orbits obtained between 2009 August and 2010 December
with WFC3.
A total of five nights of observations were obtained at the NASA
InfraRed Telescope Facility (IRTF) with the NSFCAM2 camera in the L'
band, centered at 3.76um.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 100 118 List of the candidate multiple systems with
projected separations less than 1000AU
table2.dat 100 341 List of the YSOs without a companion
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See also:
J/ApJS/224/5 : Herschel Orion Protostar Survey (HOPS): SEDs (Furlan+, 2016)
J/ApJ/818/59 : IN-SYNC. IV. YSOs in Orion A (Da Rio+, 2016)
J/ApJ/767/36 : APEX observations of HOPS protostars (Stutz+, 2013)
J/AJ/144/192 : Spitzer survey of Orion A & B. I. YSO catalog (Megeath+, 2012)
J/AJ/144/31 : Spitzer+2MASS photom. of protostar candidates (Kryukova+, 2012)
J/ApJ/731/8 : Multiple star formation in Taurus-Auriga (Kraus+, 2011)
J/ApJS/184/18 : Spitzer survey of young stellar clusters (Gutermuth+, 2009)
J/AJ/135/2496 : Near-IR survey of Class I protostars (Connelley+, 2008)
J/AJ/134/2272 : Visual binaries in the Orion Nebula Cluster (Reipurth+, 2007)
Byte-by-byte Description of file: table[12].dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1 A1 --- Type Source type (0=protostars, 1=stars with disks)
3- 11 A9 --- Name Source identifier (2)
13 I1 h RAh Hour of Right Ascension (J2000)
15- 16 I2 min RAm Minute of Right Ascension (J2000)
18- 22 F5.2 s RAs Second of Right Ascension (J2000)
24 A1 --- DE- Sign of the Declination (J2000)
25 I1 deg DEd Degree of Declination (J2000)
27- 28 I2 arcmin DEm Arcminute of Declination (J2000)
30- 34 F5.2 arcsec DEs Arcsecond of Declination (J2000)
36- 41 F6.3 mag WF160W [8.2/23.2]? HST/WFC3 F160W band magnitude
43- 47 F5.3 mag e_WF160W [0.01/0.3]? Uncertainty in WF160Wmag
49- 54 F6.3 mag NF160W [8.8/20.8]? HST/NICMOS F160W band magnitude
56- 60 F5.3 mag e_NF160W [0.001/0.09]? Uncertainty in NF160Wmag
62- 67 F6.3 mag NF205W [8.2/22]? HST/NICMOS F205W band magnitude
69- 73 F5.3 mag e_NF205W [0.001/0.4]? Uncertainty in NF205Wmag
75- 80 F6.3 mag Lmag [5.1/14.5]? IRTF/NSFCAM2 L' (3.76um) band
magnitude
82- 86 F5.3 mag e_Lmag [0/0.5]? Uncertainty in Lmag
88- 90 I3 AU Sep [80/997]? Projected separation
(only for table 1)
92-100 A9 --- CName Common identifier
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Note (2):
MGM = Megeath et al. (2012, J/AJ/144/192; <[MGM2012] NNNN> in Simbad).
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 20-Jun-2016