J/ApJ/799/155 Sub-stellar companions in Taurus (Daemgen+, 2015)
Sub-stellar companions and stellar multiplicity in the Taurus star-forming
region.
Daemgen S., Bonavita M., Jayawardhana R., Lafreniere D., Janson M.
<Astrophys. J., 799, 155 (2015)>
=2015ApJ...799..155D 2015ApJ...799..155D
ADC_Keywords: Stars, double and multiple ; Photometry, infrared ; Stars, masses
Keywords: binaries: visual; planets and satellites: detection; stars: formation;
stars: pre-main sequence
Abstract:
We present results from a large, high-spatial-resolution near-infrared
imaging search for stellar and sub-stellar companions in the
Taurus-Auriga star-forming region. The sample covers 64 stars with
masses between those of the most massive Taurus members at ∼3M☉
and low-mass stars at ∼0.2M☉. We detected 74 companion
candidates, 34 of these reported for the first time. Twenty-five
companions are likely physically bound, partly confirmed by follow-up
observations. Four candidate companions are likely unrelated field
stars. Assuming physical association with their host star, estimated
companion masses are as low as ∼2MJup. The inferred multiplicity
frequency within our sensitivity limits between ∼10-1500AU is
26.3-4.9+6.6%. Applying a completeness correction, 62%±14% of
all Taurus stars between 0.7 and 1.4M☉ appear to be multiple.
Higher order multiples were found in 1.8-1.5+4.2% of the cases, in
agreement with previous observations of the field. We estimate a
sub-stellar companion frequency of ∼3.5%-8.8% within our sensitivity
limits from the discovery of two likely bound and three other
tentative very low-mass companions. This frequency appears to be in
agreement with what is expected from the tail of the stellar companion
mass ratio distribution, suggesting that stellar and brown dwarf
companions share the same dominant formation mechanism. Further, we
find evidence for possible evolution of binary parameters between two
identified sub-populations in Taurus with ages of ∼2Myr and ∼20Myr,
respectively.
Description:
All observations were obtained at the Gemini North telescope with the
NIRI instrument in Ks band (1.95-2.30um). The ALTAIR adaptive optics
(AO) system was used to obtain diffraction-limited images.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 76 72 The target sample
table2.dat 125 130 Candidate companion parameters
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See also:
I/322 : UCAC4 Catalogue (Zacharias+, 2012)
II/319 : UKIDSS-DR9 LAS, GCS and DXS Surveys (Lawrence+ 2012)
J/ApJ/757/141 : Companion IR detection limits in associations (Kraus+, 2012)
J/ApJ/751/115 : Millimeter emission from Taurus binary systems (Harris+, 2012)
J/ApJ/745/119 : Close companions to young stars. I. ChaI + Tau (Nguyen+, 2012)
J/ApJ/745/19 : Binary systems in Taurus-Auriga (Kraus+, 2012)
J/ApJ/736/89 : Search for companions around nearby stars (Janson+, 2011)
J/ApJ/731/8 : Multiple star formation in Taurus-Auriga (Kraus+, 2011)
J/ApJ/724/835 : The Spitzer c2d survey of WTTSs. III. (Wahhaj+, 2010)
J/ApJS/190/1 : A survey of stellar families (Raghavan+, 2010)
J/ApJS/186/259 : Taurus Spitzer survey: new candidate members (Rebull+, 2010)
J/ApJ/709/L114 : Protoplanetary disks in PMS binaries (Duchene, 2010)
J/A+A/509/A52 : Search for companions with VLT/NACO (Chauvin+, 2010)
J/ApJ/704/531 : The coevality of young binary systems (Kraus+, 2009)
J/ApJ/703/1511 : Wide binaries in Taurus and Upper Sco (Kraus+, 2009)
J/ApJS/181/321 : Properties of Spitzer c2d dark clouds (Evans+, 2009)
J/ApJS/181/62 : Survey of young solar analogs (Metchev+, 2009)
J/MNRAS/389/869 : Multiplicity among bright stellar systems (Eggleton+, 2008)
J/PASJ/60/209 : Faint companions around YSOs in TMC (Itoh+, 2008)
J/ApJ/662/413 : Wide multiplicity in 3 associations with 2MASS (Kraus+, 2007)
J/ApJ/647/1180 : Infrared photometry of Taurus SFR (Luhman+, 2006)
J/ApJ/645/676 : Spatial distribution of brown dwarfs in Taurus (Luhman+, 2006)
J/A+A/446/485 : New very low-mass members in Taurus (Guieu+, 2006)
J/A+A/376/982 : Near-IR observations of young binaries (Woitas+, 2001)
J/A+A/337/403 : Low-mass stars evolutionary models (Baraffe+ 1998)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 3 A3 --- Mm Membership (G1)
5- 22 A18 --- Name Target name
24 A1 --- f_Name [c] Binary system (1)
26- 27 I2 h RAh Hour of right ascension (J2000)
29- 30 I2 min RAm Minute of right ascension (J2000)
32- 36 F5.2 s RAs Second of right ascension (J2000)
38 A1 --- DE- Sign of declination (J2000)
39- 40 I2 deg DEd Degree of declination (J2000)
42- 43 I2 arcmin DEm Arcminute of declination (J2000)
45- 48 F4.1 arcsec DEs Arcsecond of declination (J2000)
50- 54 F5.2 mag Ksmag [5.9/11.2] 2MASS Ks-band magnitude
56- 59 A4 --- SpT MK spectral type
61 I1 --- r_SpT [1/6] SpT reference (2)
63- 76 A14 --- Evidence Membership evidence (3)
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Note (1):
c = DI Tau is in a binary system with classical T Tauri star DH Tau.
Note (2): Reference as follows:
1 = Nguyen et al. 2012 (J/ApJ/745/119);
2 = Walter et al. 1988AJ.....96..297W 1988AJ.....96..297W;
3 = Wichmann et al. 2000A&A...359..181W 2000A&A...359..181W;
4 = Hartigan & Kenyon 2003ApJ...583..334H 2003ApJ...583..334H;
5 = Martin & Magazzu 1999A&A...342..173M 1999A&A...342..173M;
6 = Luhman et al. 2003 (J/ApJ/593/1093)
Note (3): Evidence for Taurus membership
(analysis and references in Appendix A):
II = Class II
Li = Lithium abundance
pm = proper motion
pi = Hipparcos parallax
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 3 A3 --- Mm Membership (G1)
5- 22 A18 --- Name Target name (as in table 1)
24- 30 A7 --- m_Name Component (1)
32 A1 --- f_Name [e] Binary system (2)
34- 44 A11 "YYYY/MMM/DD" Date Observation date
46- 47 A2 --- n_Date Problematic detection (3)
49- 54 F6.3 arcsec Sep [0.08/12.6]? Binary separation
56- 60 F5.3 arcsec e_Sep [0.001/0.2]? Sep uncertainty
62- 67 F6.2 deg PA [2/358]? Position angle
69- 72 F4.2 deg e_PA [0.02/2.1]? PA uncertainty
74 A1 --- u_DelK [~] Uncertainty flag on DelK
76- 81 F6.3 mag DelK [0/12.5]? K-band magnitude difference
between the primary and the secondary
83- 87 F5.3 mag e_DelK [0.005/1]? DelK uncertainty
89 A1 --- f_DelK [p] p: primary saturated
91- 94 F4.2 Msun M1 [0.22/2.8]? Primary mass
96-100 F5.3 Msun M2 [0.002/1.3]? Secondary mass (4)
102-106 F5.3 --- M2/M1 [0/1]? Secondary to primary mass ratio (4)
108-113 E6.3 --- Edet [0/21]? Number of expected chance alignments
with unrelated background stars (5)
115-116 I2 --- Ndet [0/33]? Number of actual detections
118-119 A2 --- St Companionship status (6)
121-125 A5 --- Ref Previous reference (7)
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Note (1): When available, a commonly used identifier is used to refer to the
individual components. Other and newly discovered companion candidates
are marked with cc1,cc2, ...
Note (2):
e = The astrometry and photometry are reported with respect to the
astrometric center and combined photometry of the close pair in the
same system.
Note (3): Note as follows:
n1 = not resolved due to bad AO correction
n2 = no clear detection of faint companion
Note (4): Derived secondary masses and mass ratios assume that companions are
coeval and physically associated with their primary.
Note (5): Edet is calculated as the sum over all target stars of the number
of expected background sources that are as bright or brighter and
within the separation of the detected companion. See section 4.1.
Note (6): Companionship status after Lafreniere et al. (2014ApJ...785...47L 2014ApJ...785...47L)
as follows:
C0 = bound companion based on statistics in this paper,
C1 = bound companion based on follow-up observations in this paper,
C2 = bound companion based on other work.
B0 = unrelated background object based on statistics (this paper),
B1 = unrelated background object based on follow-up observations in this
paper.
Note (7): Previous publication of companion or "TP" if first reported in the
current paper. Reference as follows:
TP = This paper
1 = Ghez et al. 1993AJ....106.2005G 1993AJ....106.2005G
2 = Moneti & Zinnecker 1991A&A...242..428M 1991A&A...242..428M
3 = Kraus et al. 2011, Cat. J/ApJ/731/8
4 = White & Ghez 2001ApJ...556..265W 2001ApJ...556..265W
5 = Kraus & Hillenbrand 2009, Cat. J/ApJ/704/531
6 = Itoh et al. 2008, Cat. J/PASJ/60/209
7 = Kohler & Leinert 1998A&A...331..977K 1998A&A...331..977K
8 = Harris et al. 2012, Cat. J/ApJ/751/115
9 = Hartigan et al. 1994ApJ...427..961H 1994ApJ...427..961H
10 = Leinert et al. 1993A&A...278..129L 1993A&A...278..129L
11 = Joy & van Biesbroeck 1944PASP...56..123J 1944PASP...56..123J
12 = Moneti & Zinnecker 1991A&A...242..428M 1991A&A...242..428M
13 = Sartoretti et al. 1998A&A...334..592S 1998A&A...334..592S
14 = Duchene et al. 1999A&A...351..954D 1999A&A...351..954D
15 = Bonavita et al. 2014ApJ...791L..40B 2014ApJ...791L..40B
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Global notes:
Note (G1): Membership as follows:
YM = Young member
Ex = Extended sample
NM? = Likely non-member
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History:
From electronic version of the journal
(End) Emmanuelle Perret [CDS] 17-Jun-2015