J/ApJ/751/115 Millimeter emission from Taurus binary systems (Harris+, 2012)
A resolved census of millimeter emission from Taurus multiple star systems.
Harris R.J., Andrews S.M., Wilner D.J., Kraus A.L.
<Astrophys. J., 751, 115 (2012)>
=2012ApJ...751..115H 2012ApJ...751..115H
ADC_Keywords: Stars, double and multiple ; Stars, masses ;
Millimetric/submm sources
Keywords: binaries: general - protoplanetary disks - stars: formation
Abstract:
We present a high angular resolution millimeter-wave dust continuum
imaging survey of circumstellar material associated with the
individual components of 23 multiple star systems in the Taurus-Auriga
young cluster. Combined with previous measurements in the literature,
these new data permit a comprehensive look at how the millimeter
luminosity (a rough tracer of disk mass) relates to the separation and
mass of a stellar companion. Approximately one-third (28%-37%) of the
individual stars in multiple systems have detectable millimeter
emission, an incidence rate half that for single stars (∼62%) which
does not depend on the number of companions. There is a strong,
positive correlation between the luminosity and projected separation
(ap) of a stellar pair. Wide pairs (ap>300AU) have a similar
luminosity distribution as single stars, medium pairs
(ap~30-300AU) are a factor of five fainter, and close pairs
(ap<30AU) are ∼5x fainter yet (aside from a small, but notable
population of bright circumbinary disks). In most cases, the emission
is dominated by a disk around the primary (or a wide tertiary in
hierarchical triples), but there is no clear relationship between
luminosity and stellar mass ratio.
Description:
23 multiple systems were observed with the Submillimeter Array (SMA)
interferometer in a variety of observing configurations and receiver
settings over the past six years (from 2005 Dec 17 to 2012 Jan 14),
with most of the data obtained in the past 20 months. All but 4 of
these 23 systems were observed with the 345GHz (880um) receivers: the
pairs in the HP Tau, GI/GK Tau, MHO 1/2, and GG Tau systems that we
aimed to probe have wide enough separations that they were instead
observed with slightly lower resolution at 230GHz (1.3mm).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table4.dat 68 14 Resolved disk properties
table5.dat 52 49 Unresolved disk properties
table6.dat 109 111 Properties of stellar pairs in Taurus
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See also:
J/ApJ/745/19 : Binary systems in Taurus-Auriga (Kraus+, 2012)
J/ApJ/731/8 : Multiple star formation in Taurus-Auriga (Kraus+, 2011)
J/ApJ/720/480 : DISCS. I. Taurus protoplanetary disk data (Oberg+, 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/AJ/129/2294 : RVs of weak-lines T Tauri stars (Massarotti+, 2005)
Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 11 A11 --- Name Stellar component name
13- 14 I2 h RAh Hour of right ascension (J2000) (1)
16- 17 I2 min RAm Minute of right ascension (J2000)
19- 23 F5.2 s RAs Second of right ascension (J2000)
25 A1 --- DE- Sign of declination (J2000) (1)
26- 27 I2 deg DEd Degree of declination (J2000) (1)
29- 30 I2 arcmin DEm Arcminute of declination (J2000)
32- 36 F5.2 arcsec DEs Arcsecond of declination (J2000)
38- 40 I3 mJy Fd [24/557] Flux density at 880um (or 1.3mm)
42 I1 mJy e_Fd [1/6] Fd uncertainty
44 A1 --- f_Fd [n] n: measurements at a wavelength of 1.3mm
46- 48 I3 AU Rad [57/305] Disk radius
50- 51 I2 AU- e_Rad [1/63] Rad uncertainty
53- 54 I2 deg inc [6/84] Disk inclination angle, where 0° is
face-on
56- 57 I2 deg e_inc [1/21]? inc uncertainty
59 A1 --- f_inc [f] f: fixed in the modeling (see Section 4)
61- 63 I3 deg PA [7/174] Position angle (E of N) of the disk
major axis projected on the sky
65- 66 I2 deg e_PA [1/36]? PA uncertainty
68 A1 --- f_PA [f] f: fixed in the modeling (see Section 4)
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Note (1): Adopted disk center coordinates.
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Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
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1- 13 A13 --- Name Stellar component name
15 A1 --- f_Name [i] i: Fd values from single-dish photometry
(Andrews & Williams 2005ApJ...631.1134A 2005ApJ...631.1134A)
17- 18 I2 h RAh Hour of right ascension (J2000) (1)
20- 21 I2 min RAm Minute of right ascension (J2000)
23- 27 F5.2 s RAs Second of right ascension (J2000)
29 A1 --- DE- Sign of declination (J2000) (1)
30- 31 I2 deg DEd Degree of declination (J2000) (1)
33- 34 I2 arcmin DEm Arcminute of declination (J2000)
36- 40 F5.2 arcsec DEs Arcsecond of declination (J2000)
42 A1 --- l_Fd Limit flag on Fd
44- 47 I4 mJy Fd [3/2360] 880um (or 1.3mm) flux density
49- 50 I2 mJy e_Fd [1/90]? Fd uncertainty
52 A1 --- f_Fd [n] n: measurements at a wavelength of 1.3mm
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Note (1): Disk center coordinates.
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Byte-by-byte Description of file: table6.dat
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Bytes Format Units Label Explanations
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1- 19 A19 --- Name System name
21- 38 A18 --- comp1 Primary designation of specified pair (1)
40- 57 A18 --- comp2 Secondary designation of specified pair (1)
59 A1 --- l_rho Limit flag on rho
61- 67 F7.4 arcsec rho [0.0004/28] Angular separation ρ
69 A1 --- u_q [~] Uncertainty flag on q
71- 74 F4.2 --- q [0.02/1]? Mass ratio of the pair (M2/M1)
76 A1 --- l_M1 Limit flag on M1
78- 81 F4.2 Msun M1 [0.1/4.2] Estimated stellar mass of the
primary component of the pair
83 A1 --- l_Fc Limit flag on Fc
85- 88 I4 mJy Fc [3/2390]? Composite 880um (or 1.3mm) flux
density or upper limit for the pair
90- 91 I2 mJy e_Fc [1/90]? Fc uncertainty
93 A1 --- n_Fc [n] n: Fc measured at 1.3mm (2)
95-103 A9 --- Ref Reference(s) for rho, q and Fc (3)
105-109 A5 --- n_Ref [a-d, ] Individual notes and remarks (4)
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Note (1): Note that this can consist of more than one star; see Section 2.
Note (2): The analysis in Section 5 assumes a conservative scaling by a factor
(1.3/0.88)2∼2.2.
Note (3): Reference as follows:
1 = Kraus et al. (2011, Cat. J/ApJ/731/8),
2 = Boden et al. (2007ApJ...670.1214B 2007ApJ...670.1214B),
3 = Duchene et al. (2003ApJ...592..288D 2003ApJ...592..288D),
4 = Kraus & Hillenbrand (2009, Cat. J/ApJ/703/1511),
5 = Mathieu (1994ARA&A..32..465M 1994ARA&A..32..465M),
6 = Duchene et al. (2006A&A...457L...9D 2006A&A...457L...9D),
7 = Correia et al. (2006A&A...459..909C 2006A&A...459..909C),
8 = Itoh et al. (2005ApJ...620..984I 2005ApJ...620..984I),
9 = Massarotti et al. (2005, Cat. J/AJ/129/2294),
10 = White et al. (1999ApJ...520..811W 1999ApJ...520..811W),
11 = Jensen et al. (2007AJ....134..241J 2007AJ....134..241J),
12 = Kraus & Hillenbrand (2009, Cat. J/ApJ/704/531),
13 = Schaefer et al. (2006AJ....132.2618S 2006AJ....132.2618S),
14 = Mathieu et al. (1997AJ....113.1841M 1997AJ....113.1841M),
15 = White & Hillenbrand (2005ApJ...621L..65W 2005ApJ...621L..65W); and
A = this article,
B = Andrews & Williams (2005ApJ...631.1134A 2005ApJ...631.1134A),
C = Osterloh & Beckwith (1995ApJ...439..288O 1995ApJ...439..288O), and
D = Schaefer et al. (2009ApJ...701..698S 2009ApJ...701..698S).
Note (4): Flag as follows:
a = The marginal detections of millimeter emission in the V773 Tau and
V410 Tau systems by Andrews & Williams (2005ApJ...631.1134A 2005ApJ...631.1134A) are
likely unrelated to circumstellar dust. Both systems are known to
emit relatively strong synchrotron radio signals (Massi et al.
2006A&A...453..959M 2006A&A...453..959M; Bieging et al. 1984ApJ...282..699B 1984ApJ...282..699B). To be
conservative, we consider these systems to have only upper limits on
their millimeter luminosities. Synchrotron contamination from T Tau Sab
is also likely to dominate over thermal emission from dust, even at
millimeter wavelengths (see Loinard et al. 2007ApJ...671..546L 2007ApJ...671..546L).
The millimeter emission from the XZ Tau binary may also be
contaminated, given its relatively bright centimeter-wave signal (see
Carrasco-Gonzalez et al. 2009ApJ...693L..86C 2009ApJ...693L..86C). Moriarty-Schieven et
al. (2006ApJ...645..357M 2006ApJ...645..357M) suggest a smaller 880um flux density of ∼10mJy.
b = The V773 Tau A-B mass ratio was computed assuming the V773 Tau Aab system
mass from Boden et al. (2007ApJ...670.1214B 2007ApJ...670.1214B). V773 Tau C is an "infrared
companion" (Duchene et al. 2003ApJ...592..288D 2003ApJ...592..288D), so there are no reliable
estimates of its mass to compute q. The total mass of LkCa 3 Aab
estimated by Kraus et al. (2011, Cat. J/ApJ/731/8) was used to help
determine the mass ratio of the spectroscopic binary. The Duchene et al.
(2006A&A...457L...9D 2006A&A...457L...9D) results were used in conjunction with the
measurements of White & Ghez (2001ApJ...556..265W 2001ApJ...556..265W) to estimate the T Tau
Sab-N mass ratio. The DH Tau AB and GG Tau Bab mass ratios implicitly
assume the Mp values derived by Kraus et al. (2011, Cat. J/ApJ/731/8).
The mass ratio for J1-4872 Bab was estimated from the spectral type and
K-band magnitude difference from Correia et al. (2006A&A...459..909C 2006A&A...459..909C),
as described by Kraus et al. (2011, Cat. J/ApJ/731/8).
c = The single-lined spectroscopic binaries LkCa 3 Aab and UZ Tau Eab have
a separation weighted by an unknown factor of sini and a mass ratio
proportional to (sini)3 (although an independent inclination estimate
is available for UZ Tau Eab, assuming its gas disk is coplanar; see
Simon et al. 2000ApJ...545.1034S 2000ApJ...545.1034S). The double-lined spectroscopic
binaries V826 Tau AB and DQ Tau have only their separations weighted by
sini; the mass ratios are determined precisely. White & Hillenbrand
(2005ApJ...621L..65W 2005ApJ...621L..65W) demonstrated that St 34 Aab is a single-lined
spectroscopic binary, but did not have sufficient radial velocity data
to constrain the orbit. The V773 Tau B-C projected separation was
estimated using the weighted mean position offsets at the same epochs
from Duchene et al. (2003ApJ...592..288D 2003ApJ...592..288D).
d = Although the current projected separation for the T Tau Sab-N pair is
∼0.7" (Duchene et al. 2006A&A...457L...9D 2006A&A...457L...9D), astrometric monitoring of
the pair suggests that the true separation is likely substantially
larger. Kohler et al. (2008A&A...482..929K 2008A&A...482..929K) suggest that the pair may
be near periastron on an eccentric orbit with a much larger true
separation, a ∼1500AU, than would be suggested by the projected distance
on the sky. In the analysis of Section 5, we adopt their estimate, but
note that the major features of our statistical analysis do not depend
on that decision.
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History:
From electronic version of the journal
(End) Emmanuelle Perret [CDS] 18-Dec-2013