J/A+A/629/A94 CO spectra of 49 semi-regular variables (Diaz-Luis+, 2019)
Circumstellar envelopes of semi-regular long-period variables:
mass-loss rate estimates and general model fitting of the molecular gas.
Diaz-Luis J.J., Alcolea J., Bujarrabal V., Santander-Garcia M.,
Castro-Carrizo A., Gomez-Garrido M., Desmurs J.-F.
<Astron. Astrophys. 629, A94 (2019)>
=2019A&A...629A..94D 2019A&A...629A..94D (SIMBAD/NED BibCode)
ADC_Keywords: Stars, variable ; Carbon monoxide ; Spectra, radio
Keywords: stars: AGB and post-AGB - circumstellar matter - stars: evolution -
stars: mass-loss - radio lines: stars
Abstract:
We aim to study the main properties of a volume-limited unbiased
sample of well characterized semi-regular variables (SRs) in order to
clarify important issues that need to be further explained, such as
the formation of axially symmetric planetary nebulae (PNe) from
spherical circumstellar envelopes (CSEs) that takes place during the
mass loss process along the AGB phase.
We present new high S/N IRAM 30m observations of the 12CO J=2-1,
12CO J=1-0, and 13CO J=1-0 lines, in a volume-limited sample of SRs
for which the Hipparcos distances are between 100-500 pc and
declinations above -25°. We analyzed the data by characterizing
the main properties of the CSEs. The 12CO J=2-1 data have been used
to study the profiles, while the 12CO J=1-0 data have been used to
estimate mass-loss rates for the complete sample. Moreover, the 12CO
J=2-1 line has been used to determine the possible structures
responsible for such profiles.
We have classified the sources into four groups according to the
different profiles and final gas expansion velocities. Type 1 and 2
profiles are broad and narrow symmetric lines, respectively. Type 1
profiles, furthermore, are more related to standard spherically
symmetric envelopes already studied. Type 3 profiles, on the contrary,
are strange profiles with very pronounced asymmetries. Type 4
profiles, finally, are those which show two different components: a
narrow line profile superimposed on a broad pedestal component. We
find that for sources which show this kind of profile, with two
different components, the variation amplitude is very low, what means
that these SRs do not have a well developed inner envelope
differentiated from the outer one. Interestingly, we report a moderate
correlation between mass-loss rates and 12CO J=1-0/12CO J=2-1 line
intensity ratios for O-rich SRs, suggesting a different behaviour
between C- and O-rich SRs. By using SHAPE+shapemol, we find a unified
simple model based on an oblate spheroid, placed in different
orientations, that may explain all the 12CO profiles in the sample,
indicating that the gas expansion is, in general, predominantly
equatorial. Moreover, in order to explain the type 4 profiles, we
define an extra component which may somehow be a biconical structure
or similar according to the structures already found in this kind of
sources. Type 1 and 2 profiles, curiously, may also be explained by
standard spherically symmetric envelopes, but often requiring
anomalously low velocities. Type 3 and 4 profiles, however, need axial
symmetry to be explained. We conclude that most circumstellar shells
around SRs show axial, strongly non-spherical symmetry. More
interferometric observations are needed in order to make firm
conclusions about mass-loss processes and possible morphologies of
SRs.
Description:
The table contains all the spectra for the 49 sources of the sample
(with a blank space between them). We include the name of the source
and the line (note that we are using three different lines: 12CO
J=2-1, 12CO J=1-0, and 13CO J=1-0) in the first line of every
dataset. Moreover, the columns contain the velocity in km/s (first
column) and the main-beam brightness temperature in K (second column).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 66 49 Main properties of the observed sample of SRs
spectra.dat 53 14700 *All spectra for the 49 sources of the sample
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Note on spectra.dat: blank line between spectra.
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Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- Star Star name
12- 13 I2 h RAh Simbad right ascension (J2000)
15- 16 I2 min RAm Simbad right ascension (J2000)
18- 19 I2 s RAs Simbad right ascension (J2000)
21 A1 --- DE- Declination sign (J2000)
22- 23 I2 deg DEd Declination (J2000)
25- 26 I2 arcmin DEm Declination (J2000)
28- 29 I2 arcsec DEs Declination (J2000)
31- 33 A3 --- Vtype [SRa SRb SRc] Variable type
35- 37 I3 d Per Period of variability
39 A1 --- SpType [CMS] Spectral type
41- 43 F3.1 mag DVmag Variation amplitude, from GCVS
(Samus et al., Cat. B/gcvs)
45- 47 I3 Jy F12 IRAS 12um flux
49- 51 I3 Jy F25 IRAS 25um flux
53- 54 I2 Jy F60 IRAS 60um flux
56- 57 I2 Jy F100 IRAS 100um flux
59- 61 I3 pc DistH Distance derived from Hipparcos
(van Leeuwen, 2007, Cat. I/311) parallax
63- 66 I4 pc DistG Distance derived from Gaia DR2
(Gaia Collaboration, 2018, Cat. I/345) parallax
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Byte-by-byte Description of file: spectra.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- Star Star name
13- 21 A9 --- Line Line (12CO(1-0), 12CO(2-1) or 13CO(1-0))
32- 40 F9.4 km/s Vel Velocity
43- 53 E11.6 K Tmb Main-beam brightness temperature
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Acknowledgements:
Jose Jairo Diaz-Luis, jjairo(at)oan.es
(End) Patricia Vannier [CDS] 24-Jul-2019