J/A+A/576/A109 YSOs APEX-CHAMP+ high-J CO maps (Yildiz+, 2015)
APEX-CHAMP+ high-J CO observations of low-mass young stellar objects.
IV. Mechanical and radiative feedback.
Yildiz U.A., Kristensen L.E., van Dishoeck E.F., Hogerheijde M.R.,
Karska A., Belloche A., Endo A., Frieswijk W., Gusten R., van Kempen T.A.,
Leurini S., Nagy Z., Perez-Beaupuits J.P., Risacher C., van der Marel N.,
van Weeren R.J., Wyrowski F.
<Astron. Astrophys. 576, A109 (2015)>
=2015A&A...576A.109Y 2015A&A...576A.109Y
ADC_Keywords: YSOs ; Carbon monoxide
Keywords: astrochemistry - stars: formation - stars: protostars -
ISM: molecules - techniques: spectroscopic
Abstract:
During the embedded stage of star formation, bipolar molecular
outflows and UV radiation from the protostar are important feedback
processes. Both processes reflect the accretion onto the forming star
and affect subsequent collapse or fragmentation of the cloud.
Our aim is to quantify the feedback, mechanical and radiative, for a
large sample of low-mass sources in a consistent manner. The outflow
activity is compared to radiative feedback in the form of UV heating
by the accreting protostar to search for correlations and evolutionary
trends.
Large-scale maps of 26 young stellar objects, which are part of the
Herschel WISH key program are obtained using the CHAMP+ instrument on
the Atacama Pathfinder EXperiment (12CO and 13CO 6-5; Eup∼100K),
and the HARP-B instrument on the James Clerk Maxwell Telescope (12CO
and 13CO 3-2; Eup∼30K). The maps have high spatial resolution,
particularly the CO 6-5 maps taken with a 9" beam, resolving the
morphology of the outflows. The maps are used to determine outflow
parameters and the results are compared with higher-J CO lines
obtained with Herschel. Envelope models are used to quantify the
amount of UV-heated gas and its temperature from 13CO 6-5
observations.
All sources in our sample show outflow activity, with the spatial
extent decreasing from the Class 0 to the Class I stage. Consistent
with previous studies, the outflow force, FCO, is larger for Class 0
sources than for Class I sources, even if their luminosities are
comparable. The outflowing gas typically extends to much greater
distances than the power-law envelope and therefore influences the
surrounding cloud material directly. Comparison of the CO 6-5 results
with HIFI H2O and PACS high-J CO lines, both tracing currently shocked
gas, shows that the two components are linked, even though the
transitions do not probe the same gas. The link does not extend down
to CO 3-2. The conclusion is that CO 6-5 depends on the shock
characteristics (density and velocity), whereas CO 3-2 is more
sensitive to conditions in the surrounding environment (density). The
radiative feedback is responsible for increasing the gas temperature
by a factor of two, up to 30-50K, on scales of a few thousand AU,
particularly along the direction of the outflow. The mass of the UV
heated gas exceeds the mass contained in the entrained outflow in the
inner ∼3000AU and is therefore at least as important on small scales.
Description:
Files contain the observations of 12CO and 13CO 3-2 from
JCMT-HARP-B and 12CO and 13CO 6-5 from APEX-CHAMP+, toward 26 low
mass protostars as listed below. The data analysis was done via
GILDAS-CLASS, where raw data are processed to obtain regularly sampled
data.
The spectra are given in two formats; fits cube and GILDAS lmv cube.
File names are self explanatory, i.e.,
SOURCENAMEMOLECULETRANSITIONTELESCOPENAMEcube_VELOCITYRESOLUTION.fits
and
SOURCENAMEMOLECULETRANSITIONTELESCOPENAMEcube_VELOCITYRESOLUTION.lmv
File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
list.dat 184 85 List of FITS and GILDAS datacubes
fits/* . 85 Individual FITS datacubes
gildas/* . 85 Individual GILDAS datacubes
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Byte-by-byte Description of file: list.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 2 I2 h RAh Right ascension of centre (J2000)
4- 5 I2 min RAm Right ascension of centre (J2000)
7- 10 F4.1 s RAs Right ascension of centre (J2000)
12 A1 --- DE- Declination sign of centre (J2000)
13- 14 I2 deg DEd Declination of centre (J2000)
16- 17 I2 arcmin DEm Declination of centre (J2000)
19- 22 F4.1 arcsec DEs Declination of centre (J2000)
24- 27 F4.2 arcsec/pix Scale [4.5/9.31] Scale of the image
29- 30 I2 --- Nx [17/99] Number of pixels along X-axis
32- 34 I3 --- Ny [16/137] Number of pixels along Y-axis
36- 39 I4 --- Nz [110/4000] Number of frequencies
41- 47 F7.1 km/s V.min [-549/-19] Lower value of velocity interval
49- 55 F7.1 km/s V.max [30/396] Upper value of velocity interval
57- 59 I3 m/s dV [200/664] Velocity resolution
62- 66 F5.1 Mibyte size [0.5/143] Size of the FITS file
69-101 A33 --- SName Simbad name of the source
103-141 A39 --- FileName Name of the FITS file in subdirectory fits
143-180 A38 --- GName Name of the GILDAS file in subdirectory
gildas
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Acknowledgements:
Umut Yildiz, Umut.Yildiz(at)jpl.nasa.gov
References:
van Kempen et al., Paper I 2009A&A...501..633V 2009A&A...501..633V
van Kempen et al., Paper II 2009A&A...507.1425V 2009A&A...507.1425V
Yildiz et al., Paper III 2012A&A...542A..86Y 2012A&A...542A..86Y
(End) Umut Yildiz [NASA/JPL-Caltech], Patricia Vannier [CDS] 15-Jan-2015