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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 (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:
FileName Lrecl Records Explanations
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
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.
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
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
Byte-by-byte Description of file: tablec2.dat
Bytes Format Units Label Explanations
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)
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) 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.
Byte-by-byte Description of file: refs.dat
Bytes Format Units Label Explanations
1- 3 A3 --- Ref Reference code 5- 23 A19 --- BibCode BibCode 25- 46 A22 --- Aut Author's name 49- 67 A19 --- Com Comments
History: From electronic version of the journal
(End) Patricia Vannier [CDS] 24-May-2017
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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