J/A+A/599/A14 Taurus ultra-wide pairs (Joncour+, 2017)
Multiplicity and clustering in Taurus star-forming region.
I. Unexpected ultra-wide pairs of high-order multiplicity in Taurus.
Joncour I., Duchene G., Moraux E.
<Astron. Astrophys., 599, A14-14 (2017)>
=2017A&A...599A..14J 2017A&A...599A..14J (SIMBAD/NED BibCode)
ADC_Keywords: Molecular clouds ; Stars, double and multiple
Keywords: stars: variables: T Tauri, Herbig Ae/Be - binaries: general -
binaries: visual - methods: data analysis - stars: statistics
Abstract:
This work analyses the spatial distribution of stars in Taurus with a
specific focus on multiple stars and wide pairs in order to derive new
constraints on star formation and early dynamical evolution scenarios.
We collected the multiplicity data of stars in Taurus to build an
up-to-date stellar/multiplicity catalog. We first present a general
study of nearest-neighbor statistics on spatial random distribution,
comparing its analytical distribution and moments to those obtained
from Monte Carlo samplings. We introduce the one-point correlation
Ψ function to complement the pair correlation function and define
the spatial regimes departing from randomness in Taurus. We then
perform a set of statistical studies to characterize the binary regime
that prevails in Taurus.
The Ψ function in Taurus has a scale-free trend with a similar
exponent as the correlation function at small scale. It extends almost
3 decades up to ∼60kAU showing a potential extended wide binary
regime. This was hidden in the correlation function due to the
clustering pattern blending. Distinguishing two stellar populations,
single stars versus multiple systems (separation ≤1kAU), within Class
II/III stars observed at high angular resolution, we highlight a major
spatial neighborhood difference between the two populations using
nearest-neighbor statistics. The multiple systems are three times more
likely to have a distant companion within 10kAU when compared to
single stars. We show that this is due to the presence of most
probable physical ultra-wide pairs (UWPs, defined as such from their
mutual nearest neighbor property), that are themselves generally
composed of multiple systems containing up to five stars altogether.
More generally, our work highlights; 1) a new large population of
candidate UWPs in Taurus within the range 1-60kAU in Taurus and 2) the
major local structural role they play up to 60kAU. There are three
different types of UWPs; either composed of two tight and
comparatively massive stars (MM), by one single and one multiple (SM),
or by two distant low-mass singles (SS) stars. These UWPs are biased
towards high multiplicity and higher-stellar-mass components at
shorter separations. The multiplicity fraction per ultra-wide pair
with separation less than 10kAU may be as high as 83.5±19.6%.
We suggest that these young pre-main sequence UWPs may be pristine
imprints of their spatial configuration at birth resulting from a
cascade fragmentation scenario of the natal molecular core. They could
be the older counterparts, at least for those separated by less than
10kAU, to the ≤0.5Myr prestellar cores/Class 0 multiple objects
observed at radio/millimeter wavelengths.
Description:
Although a recent catalog of Taurus members has been released
including newly detected mid-infrared Wide-field Infrared Survey
Explorer (WISE) sources (Esplin et al., 2014, Cat. J/ApJ/784/126), we
adopted the catalog containing 352 Taurus members that offers a full
census of members down to 0.02 M☉(Luhman et al., 2010, Cat.
J/ApJS/186/111; Rebull et al., 2010, Cat. J/ApJS/186/259), which we
supplemented with stellar multiplicity data.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablec1.dat 124 338 *Taurus stars catalog
tablec2.dat 85 245 *Catalog of the first nearest neighbor couples
of stars
refs.dat 67 34 References
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Note on tablec1.dat: This catalog was built from Luhman et al. (2010, Cat.
J/ApJS/186/111) and Kirk & Myers (2011, Cat. J/ApJ/727/64). All the multiple
systems with a separation less than 1kAU is set to be one entry (see Sect. 2).
The following sources are listed in Luhman et al. (2010, Cat. J/ApJS/186/111)
but not included here: HBC351, HBC352, HBC353, HBC355(+354), HBC356,
V410TauAnon20, LH0422+15, CIDA13.
Note on tablec2.dat: Amongst the first-nearest-neighbor couples of stars (A, B),
the ultra wide Pairs (UWPs) are defined as mutual first nearest neighbors.
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See also:
J/AJ/135/2496 : Near-IR survey of Class I protostars (Connelley+, 2008)
J/ApJS/186/111 : Spitzer observations of Taurus members (Luhman+, 2010)
J/ApJS/186/259 : Taurus Spitzer survey: new candidate members (Rebull+, 2010)
J/ApJ/731/8 : Multiple star formation in Taurus-Auriga (Kraus+, 2011)
J/ApJ/727/64 : Young stellar groups 7 their most massive stars (Kirk+, 2011)
J/ApJ/757/141 : Companion IR detection limits in young associations
(Kraus+, 2012)
J/ApJ/784/126 : Infrared photometry of all known members in Taurus
(Esplin+, 2014)
J/ApJ/799/155 : Sub-stellar companions in Taurus (Daemgen+, 2015)
Byte-by-byte Description of file: tablec1.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 I3 --- Seq [1/338] Sequential number
5- 21 A17 --- 2MASS 2MASS name (JHHMMSSss+DDMMSSs)
23- 40 A18 --- Name Name
42- 47 F6.3 deg RAdeg Right ascension (J2000)
49- 53 F5.2 deg DEdeg Declination (J2000)
55- 59 A5 --- SpType Spectral type
61- 65 F5.3 Msun Mass Mass of the primary
67- 69 A3 --- Class Class
71 I1 --- Nstars Total number of stars within 1000AU
(spectroscopic binaries not counted as
membership)
73- 79 F7.4 arcsec Sep1 ? Separation of companions stars with the
primary
80 A1 --- --- [,/]
81- 87 F7.4 arcsec Sep2 ? Separation of companions stars with the
primary
88 A1 --- --- [,]
89- 94 F6.4 arcsec Sep3 ? Separation of companions stars with the
primary
95 A1 --- HAR [Y/N] Flag wether the stellar system/star has
been observed at High Angular Resolution
97-124 A28 --- Ref References papers associated to each
star/stellar system, in refs.dat file
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Byte-by-byte Description of file: tablec2.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- Seq [1/245] Couple sequential number
5- 7 I3 ---- StarA Star A identification number, as in tablec1.dat
9- 10 A2 --- n_StarA [S ] Note on StarA (1)
12- 30 A19 --- NameA Common name for star A
32 I1 ---- NstarsA Total number of stars (2)
34- 36 A3 --- ClassA Star A class (primary star)
38- 40 I3 ---- StarB Star B identification number, as in tablec1.dat
42 A1 --- n_StarB [S] Note on StarB (1)
44- 62 A19 --- NameB Common name for star B
64 I1 ---- NstarsB Total number of stars (2)
66- 68 A3 --- ClassB Star B class
70- 76 I7 AU deltaP Separation of the two stellar components A and B
78 I1 --- Nstars Total number of stars as a (hierarchical) couple
for the two stellar components A and B
80- 81 A2 --- HAR [-* ] Flag (3)
83 A1 --- WP [C] C for ultra wide pair candidate since the
couple are mutual nearest neighbours
85 A1 --- Conf [Y] Y for couple has been confirmed as
gravitationally bound binaries (4)
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Note (1): Presence of a spectroscopic binary associated to the star/stellar
system as follows:
S = one spectroscopic binary
SS = two spectroscopic binaries
Note (2): Total number of stars, above the unity if the star is not single
(spectroscopic binaries are counted as one component)
Note (3): Flag to indicate whether the each star A and B has been observed
as follows:
** = high angular resolution
* = only one component has been observed at HAR
- = none of them have been observed at HAR
Note (4): Y indicates that this couple has been confirmed as gravitationally
bound binaries using astrometric and spectroscopic techniques as reported in
the work of Kraus & Hillenbrand (2009ApJ...703.1511K 2009ApJ...703.1511K) who focused on binaries
with separation less than 4200AU. The delimitation of separation range in
their study is marked by a single horizontal line in the table.
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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- 3 A3 --- Ref Reference code
5- 23 A19 --- BibCode BibCode
25- 46 A22 --- Aut Author's name
49- 67 A19 --- Com Comments
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 24-May-2017