J/MNRAS/469/3881 Embedded binaries and their dense cores (Sadavoy+, 2017)
Embedded binaries and their dense cores.
Sadavoy S.I., Stahler S.W.
<Mon. Not. R. Astron. Soc., 469, 3881-3900 (2017)>
=2017MNRAS.469.3881S 2017MNRAS.469.3881S (SIMBAD/NED BibCode)
ADC_Keywords: Molecular clouds ; Stars, double and multiple ;
Photometry, millimetric/submm
Keywords: binaries: general - stars: formation - ISM: clouds - dust, extinction
Abstract:
We explore the relationship between young, embedded binaries and their
parent cores, using observations within the Perseus Molecular Cloud.
We combine recently published Very Large Array observations of young
stars with core properties obtained from Submillimetre Common-User
Bolometer Array 2 observations at 850µm. Most embedded binary
systems are found towards the centres of their parent cores, although
several systems have components closer to the core edge. Wide
binaries, defined as those systems with physical separations greater
than 500au, show a tendency to be aligned with the long axes of their
parent cores, whereas tight binaries show no preferred orientation. We
test a number of simple, evolutionary models to account for the
observed populations of Class 0 and I sources, both single and binary.
In the model that best explains the observations, all stars form
initially as wide binaries. These binaries either break up into
separate stars or else shrink into tighter orbits. Under the
assumption that both stars remain embedded following binary break-up,
we find a total star formation rate of 168Myr-1. Alternatively, one
star may be ejected from the dense core due to binary break-up. This
latter assumption results in a star formation rate of 247Myr-1.
Both production rates are in satisfactory agreement with current
estimates from other studies of Perseus. Future observations should be
able to distinguish between these two possibilities. If our model
continues to provide a good fit to other star-forming regions, then
the mass fraction of dense cores that becomes stars is double what is
currently believed.
Description:
We combine the uniform and complete binary data base from the VANDAM
survey (Tobin et al., 2016, Cat. J/ApJ/818/73) with newly identified
cores from SCUBA-2 observations at 850um (Chen et al.,
2016ApJ...826...95C 2016ApJ...826...95C) for the Perseus molecular cloud.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 70 55 Embedded binary systems
table2.dat 53 24 Dense cores associated with embedded multiples
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See also:
J/ApJ/818/73 : Study of protostars in Perseus molecular cloud (Tobin+, 2016)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 12 A12 --- Source Source name, Taken from Tobin et al.
(2016, Cat. J/ApJ/818/73),
14 A1 --- n_Source [d] Note on Source (1)
17- 20 A4 --- Class Class, Taken from Tobin et al. (2016,
Cat. J/ApJ/818/73) (2)
22 A1 --- n_Class [d] Note on Class (1)
25- 28 I4 AU D Separation between each embedded source and
the core centre (3)
33- 56 A24 --- CoreName Core IAU designation, JCMTLSG JHHMMSS.s+DDMMSS
65- 70 A6 --- CoreId Core identification number, SC2_NN (4)
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Note (1): d: B1-bS and B1-bN binary are identified as two distinct objects
with getsources, although they share a common envelope (see text).
We consider B1-bS and B1-bN to be part of the same system and use the core
centred on B1-bS for our analysis. These objects are classified as first
hydrostatic cores (FHSC) in Tobin et al. (2016, Cat. J/ApJ/818/73).
Note (2): For simplicity, we consider the stellar components identified as
Class 0/I to be Class I objects and all components identified as first
hydrostatic cores (e.g. Larson 1969MNRAS.145..271L 1969MNRAS.145..271L; Pezzuto et al.,
2012A&A...547A..54P 2012A&A...547A..54P) to be Class 0 sources. We also assume all sources within
the same core are at the same evolutionary stage (see Section 3.3).
Note (3): Separation between each embedded source and the core centre (given by
the RA/Dec coordinates) assuming a distance of 235 pc (Hirota et al.,
2008PASJ...60...37H 2008PASJ...60...37H).
Stars are ordered by increasing distance from the core centre (see Table 2).
Note (4): For brevity, we refer to the cores by their running number rather
than their full IAU name.
We also assume all sources within the same core are at the same evolutionary
stage.
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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- 6 A6 --- CoreId Core number, SC2_NN
7 A1 --- n_CoreId [b] Note on CoreId (1)
9- 10 I2 h RAh Right ascension (J2000)
12- 13 I2 min RAm Right ascension (J2000)
15- 18 F4.1 s RAs Right ascension (J2000)
20 A1 --- DE- Declination sign (J2000)
21- 22 I2 deg DEd Declination (J2000)
24- 25 I2 arcmin DEm Declination (J2000)
27- 28 I2 arcsec DEs Declination (J2000)
30- 34 F5.2 mJy/arcsec2 Speak Peak 850um flux
36- 39 F4.2 Jy Stot Total 850um flux density
41- 44 F4.1 arcsec amaj Semimajor axis
46- 49 F4.1 arcsec Bmin Semiminor axis
51- 53 I3 deg theta Position angle
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Note (1): b: The B1-b core was split into two objects with getsources.
We use the brighter core, centred with B1-bS (see the text).
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 17-Apr-2020