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J/ApJ/823/160 ALMA 106GHz continuum observations in Chamaeleon I (Dunham+, 2016)

An ALMA search for substructure, fragmentation, and hidden protostars in starless cores in Chamaeleon I. Dunham M.M., Offner S.S.R., Pineda J.E., Bourke T.L., Tobin J.J., Arce H.G., Chen X., Di Francesco J., Johnstone D., Lee K.I., Myers P.C., Price D., Sadavoy S.I., Schnee S. <Astrophys. J., 823, 160 (2016)> =2016ApJ...823..160D (SIMBAD/NED BibCode)
ADC_Keywords: Molecular clouds ; Millimetric/submm sources ; Morphology Keywords: ISM: clouds - stars: formation - stars: low-mass - submillimeter: ISM Abstract: We present an Atacama Large Millimeter/submillimeter Array (ALMA) 106 GHz (Band 3) continuum survey of the complete population of dense cores in the Chamaeleon I molecular cloud. We detect a total of 24 continuum sources in 19 different target fields. All previously known Class 0 and Class I protostars in Chamaeleon I are detected, whereas all of the 56 starless cores in our sample are undetected. We show that the Spitzer+Herschel census of protostars in Chamaeleon I is complete, with the rate at which protostellar cores have been misclassified as starless cores calculated as <1/56, or <2%. We use synthetic observations to show that starless cores collapsing following the turbulent fragmentation scenario are detectable by our ALMA observations when their central densities exceed ∼108/cm3, with the exact density dependent on the viewing geometry. Bonnor-Ebert spheres, on the other hand, remain undetected to central densities at least as high as 1010/cm3. Our starless core non-detections are used to infer that either the star-formation rate is declining in Chamaeleon I and most of the starless cores are not collapsing, matching the findings of previous studies, or that the evolution of starless cores are more accurately described by models that develop less substructure than predicted by the turbulent fragmentation scenario, such as Bonnor-Ebert spheres. We outline future work necessary to distinguish between these two possibilities. Description: We obtained ALMA observations of every source in Chamaleon I detected in the single-dish 870 µm LABOCA survey by Belloche et al. (2011, J/A+A/527/A145), except for those listed as likely artifacts (1 source), residuals from bright sources (7 sources), or detections tentatively associated with YSOs (3 sources). We observed 73 sources from the initial list of 84 objects identified by Belloche et al. (2011, J/A+A/527/A145). We observed the 73 pointings using the ALMA Band 3 receivers during its Cycle 1 campaign between 2013 November 29 and 2014 March 08. Between 25 and 27 antennas were available for our observations, with the array configured in a relatively compact configuration to provide a resolution of approximately 2" FWHM (300 AU at the distance to Chamaeleon I). Each target was observed in a single pointing with approximately 1 minute of on-source integration time. Three out of the four available spectral windows were configured to measure the continuum at 101, 103, and 114 GHz, each with a bandwidth of 2 GHz, for a total continuum bandwidth of 6 GHz (2.8 mm) at a central frequency of 106 GHz. Objects: ------------------------------------------------------- RA (ICRS) DE Designation(s) ------------------------------------------------------- 11 06 48 -77 18.0 Chamaeleon I = NAME Cha I ------------------------------------------------------- File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 62 73 ALMA 106 GHz Continuum Observations table2.dat 85 24 Observed Properties of ALMA 106 GHz Continuum Detections
See also: J/MNRAS/267/755 : Polarimetry in the Chamaeleon I Dark Cloud (McGregor+, 1994) J/A+A/357/219 : ISOCAM observations in Cha I. (Persi+, 2000) J/AJ/121/974 : JHK photometry in Cha I (Gomez+, 2001) J/AJ/121/2673 : 3µm survey of the Chamaeleon I dark cloud (Kenyon+, 2001) J/A+A/423/1029 : XMM-Newton obs, in Cha I South (Stelzer+, 2004) J/ApJ/602/816 : Chamaeleon I star-forming region census (Luhman, 2004) J/ApJ/614/267 : Chandra sources in Cha I North (Feigelson+, 2004) J/A+A/461/669 : XMM observations of Cha I dark cloud (Robrade+, 2007) J/ApJS/173/104 : Stellar population in Chamaeleon I (Luhman, 2007) J/ApJ/675/1375 : IRAC/MIPS photometry in Cha I (Luhman+, 2008) J/ApJ/684/654 : Low-mass members of Chamaeleon I (Luhman+, 2008) J/A+A/527/A145 : Chamaeleon I 870um sources (Belloche+, 2011) J/A+A/551/A46 : Compiled photometry for Cham I and II members (Lopez Marti+, 2013) J/A+A/556/A144 : Proper motions of young stars in Chamaeleon (Lopez Marti+, 2013) J/A+A/601/A97 : Gaia-ESO Survey: Cha I members (Sacco+, 2017) J/AJ/154/46 : Proper motions and photometry for members of Cha I (Esplin+, 2017) Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
1- 5 A5 --- --- [CHAI-] 6- 7 I2 --- CHAI- [01/84] Source identifier (CHAI-NN) 9- 10 I2 h RAh Hour of Right Ascension (J2000) 12- 13 I2 min RAm Minute of Right Ascension (J2000) 15- 19 F5.2 s RAs Second of Right Ascension (J2000) 21 A1 --- DE- Sign of the Declination (J2000) 22- 23 I2 deg DEd Degree of Declination (J2000) 25- 26 I2 arcmin DEm Arcminute of Declination (J2000) 28- 31 F4.1 arcsec DEs Arcsecond of Declination (J2000) 33- 36 F4.2 arcsec Bmaj Synthesized beam major axis 38- 41 F4.2 arcsec Bmin Synthesized beam minor axis 43- 48 F6.1 deg PA [] Synthesized beam position angle 50- 53 F4.2 mJy/beam rms 1σ rms of our ALMA continuum data 55- 60 F6.4 Msun/beam sigmaM 1σ mass sensitivity 62 A1 --- Status Evolutionary status (1)
Note (1): Status as follows: P = Protostellar core; S = Starless core; D = Disk, not considered a core.
Byte-by-byte Description of file: table2.dat
Bytes Format Units Label Explanations
1- 5 A5 --- --- [CHAI-] 6- 9 A4 --- CHAI- Source identifier (CHAI-NN-A) 11- 12 I2 h RAh Hour of Right Ascension (J2000) 14- 15 I2 min RAm Minute of Right Ascension (J2000) 17- 21 F5.2 s RAs Second of Right Ascension (J2000) 23 A1 --- DE- Sign of the Declination (J2000) 24- 25 I2 deg DEd Degree of Declination (J2000) 27- 28 I2 arcmin DEm Arcminute of Declination (J2000) 30- 33 F4.1 arcsec DEs Arcsecond of Declination (J2000) 35- 38 F4.2 arcsec MajAxis ? Deconvolved major axis 40- 43 F4.2 arcsec e_MajAxis ? Uncertainty in MajAxis 44 A1 --- n_MajAxis [U] Note on MajAxis (1) 46- 49 F4.2 arcsec MinAxis ? Deconvolved minor axis 51- 54 F4.2 arcsec e_MinAxis ? Uncertainty in MinAxis 55 A1 --- n_MinAxis [U] Note on MinAxis (1) 57- 61 F5.1 deg PA ? Deconvolved position angle 63- 66 F4.1 deg e_PA ? Uncertainty in PA 67 A1 --- n_PA [U] Note on PA (1) 69- 72 F4.1 mJy/beam Fpeak Peak flux density at 106 GHz 74- 76 F3.1 mJy/beam e_Fpeak Uncertainty in Fpeak 78- 81 F4.1 mJy/beam Fint Integrated flux density at 106 GHz 83- 85 F3.1 mJy/beam e_Fint Uncertainty in Fint
Note (1): Note as follows: U = Unresolved in one or both dimensions and thus unable to be deconvolved with the beam.
History: From electronic version of the journal
(End) Tiphaine Pouvreau [CDS] 15-Feb-2018
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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