J/A+A/604/A52 B213 filament 150 and 260GHz emission maps (Bracco+, 2017)
Probing changes of dust properties along a chain of solar-type prestellar and
protostellar cores in Taurus with NIKA.
Bracco A., Palmeirim P., Andre P., Adam R., Ade P., Bacmann A., Beelen A.,
Benoeet A., Bideaud A., Billot N., Bourrion O., Calvo M., Catalano A.,
Coiffard G., Comis B., D'Addabbo A., Desert F.-X., Didelon P., Doyle S.,
Goupy J., Konyves V., Kramer C., Lagache G., Leclercq S., Macias-Perez J.F.,
Maury A., Mauskopf P., Mayet F., Monfardini A., Motte F., Pajot F.,
Pascale E., Peretto N., Perotto L., Pisano G., Ponthieu N., Reveret V.,
Rigby A., Ritacco A., Rodriguez L., Romero C., Roy A., Ruppin F.,
Schuster K., Sievers A., Triqueneaux S., Tucker C., Zylka R.
<Astron. Astrophys. 604, A52 (2017)>
=2017A&A...604A..52B 2017A&A...604A..52B (SIMBAD/NED BibCode)
ADC_Keywords: Molecular clouds ; Interstellar medium
Keywords: dust, extinction - ISM: structure - stars: protostars -
stars: formation - ISM: individual objects: B213 in Taurus
Abstract:
The characterization of dust properties in the interstellar medium
(ISM) is key for understanding the physics and chemistry of star
formation. Mass estimates are crucial to determine gravitational
collapse conditions for the birth of new stellar objects in molecular
clouds. However, most of these estimates rely on dust models that need
further observational constraints to capture the relevant parameters
variations depending on the local environment: from clouds to
prestellar and protostellar cores.
We present results of a new study of dust emissivity changes based on
millimeter (mm) continuum data obtained with the NIKA camera at the
IRAM-30m telescope. Observing dust emission at 1.15mm and 2mm allows
us to constrain the dust emissivity index, β, in the
Rayleigh-Jeans tail of the dust spectral energy distribution (SED) far
from its peak emission, where the contribution of other parameters
(i.e. dust temperature) is more important. Focusing on the Taurus
molecular cloud, one of the most famous low-mass star-forming regions
in the Gould Belt, we analyze the emission properties of several
distinct objects in the B213 filament. This sub-parsec size region is
of particular interest since it is characterized by the presence of a
collection of evolutionary stages of early star formation: three
prestellar cores, two Class-0/I protostellar cores and one Class-II
object. We are therefore able to compare dust properties among a
sequence of sources that likely derive from the same parent filament.
By means of the ratio of the two NIKA channel-maps, we show that in
the Rayleigh-Jeans approximation, βRJ varies among the objects:
it decreases from prestellar cores (βRJ∼2) to protostellar
cores (βRJ∼1) and the Class-II object (βRJ∼0). For one
prestellar and two protostellar cores, we produce a robust study using
available Herschel data to constrain the dust temperature of the
sources. By using the Abel transform inversion technique we get
accurate radial temperature profiles that allow us to obtain radial
β profiles. We find systematic spatial variations of β in
the protostellar cores that is not observed in the prestellar core.
While in the former case β decreases toward the center (with
β varying between 1 and 2), in the latter it remains constant
(β=2.4±0.3). Moreover, the dust emissivity index appears
anticorrelated with the dust temperature. We discuss the implication
of these results in terms of dust grain evolution between pre- and
protostellar cores.
Description:
We present the continuum emission maps at 150 and 260GHz of the B213
filament in the Taurus molecular complex obtained with the NIKA camera
at IRAM 30m. Observations were performed during the first NIKA open
pool, in February 2014, and are presented in the paper. The maps FWHM
angular resolution is 24" (see Fig. 1). Due to the scanning strategy,
the noise rms is relatively constant in the central part of maps but
rapidly increase towards the edge.
Scales larger than 2' are filtered during the data reduction. The
image coordinates can be found in the FITS header. Three maps per
frequency are provided: flux density, noise, and time-per-pixel. Units
are MJy/sr and second, respectively.
Objects:
-----------------------------------------
RA (2000) DE Designation(s)
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04 20 51 +27 16.3 B213 = Barnard 213
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
list.dat 182 2 List of datacubes
fits/* . 2 Individual fits datacubes
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See also:
J/A+A/554/A55 : C18O(1-0) and N2H+(1-0) in L1495/B213 (Hacar+, 2013)
J/A+A/574/A104 : Dense cores in L1495/B213 complex (Tafalla+, 2015)
Byte-by-byte Description of file: list.dat
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Bytes Format Units Label Explanations
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1- 9 F9.5 deg RAdeg Right Ascension of center (J2000)
10- 18 F9.5 deg DEdeg Declination of center (J2000)
20- 22 I3 --- Nx Number of pixels along X-axis
24- 26 I3 --- Ny Number of pixels along Y-axis
28 I1 --- Nz Number of slices
30- 32 I3 Kibyte size Size of FITS file
34- 61 A28 --- FileName Name of FITS file, in subdirectory fits
63-182 A120 --- Title Title of the FITS file
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Acknowledgements:
Andra Bracco, andrea.bracco(at)cea.fr
(End) Patricia Vannier [CDS] 05-Jul-2017