J/A+A/659/A134 Binary post-AGB stars spectra (Gallardo Cava+, 2022)
Chemistry of nebulae around binary post-AGB stars:
A molecular survey of mm-wave lines.
Gallardo Cava I., Bujarrabal V., Alcolea J., Gomez-Garrido M.,
Santander-Garcia M.
<Astron. Astrophys. 659, A134 (2022)>
=2022A&A...659A.134G 2022A&A...659A.134G (SIMBAD/NED BibCode)
ADC_Keywords: Stars, giant ; Stars, double and multiple ; Spectra, radio
Keywords: stars: AGB and post-AGB - binaries: general - circumstellar matter -
radio lines: stars - ISM: planetary nebulae: general
Abstract:
There is a class of binary post-asymptotic giant branch (post-AGB)
stars that exhibit remarkable near-infrared excess. Such stars are
surrounded by Keplerian or quasi-Keplerian disks, as well as extended
outflows composed of gas escaping from the disk. This class can be
subdivided into disk- and outflow-dominated sources, depending on
whether it is the disk or the outflow that represents most of the
nebular mass, respectively. The chemistry of this type of source has
been practically unknown thus far.
Our objective is to study the molecular content of nebulae around
binary post-AGB stars that show disks with Keplerian dynamics,
including molecular line intensities, chemistry, and abundances.
We focused our observations on the 1.3, 2, 3mm bands of the 30mIRAM
telescope and on the 7 and 13 mm bands of the 40m Yebes telescope.
Our observations add up ∼600 h of telescope time. We investigated the
integrated intensities of pairs of molecular transitions for CO, other
molecular species, and IRAS fluxes at 12, 25, and 60um. Additionally,
we studied isotopic ratios, in particular 17O/18O, to analyze the
initial stellar mass, as well as 12CO/13CO, to study the line and
abundance ratios.
We present the first single-dish molecular survey of mm-wave lines in
nebulae around binary post-AGB stars. We conclude that the molecular
content is relatively low in nebulae around binary post-AGB stars, as
their molecular lines and abundances are especially weaker compared
with AGB stars. This fact is very significant in those sources where
the Keplerian disk is the dominant component of the nebula. The study
of their chemistry allows us to classify nebulae around AC Her, the
Red Rectangle, AI CMi, R Sct, and IRAS 20056+1834 as O-rich, while
that of 89 Her is probably C-rich. The calculated abundances of the
detected species other than CO are particularly low compared with AGB
stars. The initial stellar mass derived from the 17O/18O ratio for
the Red Rectangle and 89 Her is compatible with the central total
stellar mass derived from previous mm-wave interferometric maps. The
very low 12CO/13CO ratios found in binary post-AGB stars reveal a
high 13CO abundance compared to AGB and other post-AGB stars.
Description:
We performed single-dish observations of ten sources (stars.dat) using
the 30mIRAM and the 40mYebes telescopes. These sources are identified
as binary post-AGB stars with far-infrared (FIR) excess that is
indicative of material ejected by the star.
Our observations were performed using the 30m IRAM telescope (Granada,
Spain) and the 40m Yebes telescope (Guadalajara, Spain). We observed
at the 1.3, 2, 3, 7, and 13mm bands. Our observations required a total
telescope time of ∼600h distributed over two the telescopes and for
several projects.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
stars.dat 39 10 List of studied stars
list.dat 179 48 List of spectra
fits/* . 48 Individual spectra
--------------------------------------------------------------------------------
Byte-by-byte Description of file: stars.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 15 A15 --- Star Star name
17- 18 I2 h RAh Simbad right ascension (J2000)
20- 21 I2 min RAm Simbad right ascension (J2000)
23- 27 F5.2 s RAs Simbad right ascension (J2000)
29 A1 --- DE- Simbad declination sign (J2000)
30- 31 I2 deg DEd Simbad declination (J2000)
33- 34 I2 arcmin DEm Simbad declination (J2000)
36- 39 F4.1 arcsec DEs Simbad declination (J2000)
--------------------------------------------------------------------------------
Byte-by-byte Description of file: list.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 15 A15 --- Star Star name
17- 25 F9.5 deg RAdeg Right Ascension of center (J2000)
26- 34 F9.5 deg DEdeg Declination of center (J2000)
36- 41 I6 --- Nx Number of measurements
43- 65 A23 "datime" Obs.date Observation date
67- 78 E12.6 Hz bFreq Lower value of frequency interval
80- 90 E11.6 Hz BFreq Upper value of frequency interval
92-100 F9.2 Hz dFreq Frequency resolution
102-105 I4 Kibyte size Size of FITS file
107-137 A31 --- FileName Name of FITS file, in subdirectory fits
139-179 A41 --- Title Title of the FITS file
--------------------------------------------------------------------------------
Acknowledgements:
Ivan Gallardo Cava, i.gallardocava(at)oan.es
(End) Patricia Vannier [CDS] 28-Jan-2022