J/A+A/600/A71 C17O and C18O spectra of nine AGB stars (De Nutte+, 2017)
Nucleosynthesis in AGB stars traced by oxygen isotopic ratios
I. Determining the stellar initial mass by means of the 17O/18O ratio.
De Nutte, Decin L., Olofsson H., Lombaert R., de Koter A., Karakas A.,
Milam S., Ramstedt S., Stancliffe R.J., Homan W., Van de Sande M.
<Astron. Astrophys. 600, A71 (2017)>
=2017A&A...600A..71D 2017A&A...600A..71D (SIMBAD/NED BibCode)
ADC_Keywords: Stars, late-type ; Spectra, millimetric/submm
Keywords: stars: AGB and post-AGB - stars: evolution -
stars: fundamental parameters - circumstellar matter
Abstract:
We seek to investigate the 17O/18O ratio for a sample of AGB stars
containing M-, S-, and C-type stars. These ratios are evaluated in
relation to fundamental stellar evolution parameters: the stellar
initial mass and pulsation period. Circumstellar 13C16O,
12C17O, and 12C18O line observations were obtained for a
sample of nine stars with various singledish long-wavelength
facilities. Line intensity ratios are shown to relate directly to the
surface 17O/18O abundance ratio. Stellar evolution models predict
the 17O/18O ratio to be a sensitive function of initial mass and
to remain constant throughout the entire TP-AGB phase for stars
initially less massive than 5 solar masses. This makes the measured
ratio a probe of the initial stellar mass. Observed 17O/18O ratios
are found to be well in the range predicted by stellar evolution
models that do not consider convective overshooting. From this,
accurate initial mass estimates are calculated for seven sources. For
the remaining two sources, there are two mass solutions, although
there is a larger probability that the low-mass solution is correct.
Finally, we present hints at a possible separation between M/S- and
C-type stars when comparing the 17O/18O ratio to the stellar
pulsation period.
Description:
The data presented in this study were obtained with three different
telescopes. The Institut de Radio Astronomie Millimetrique (IRAM) 30m
telescope at Pico Veleta, Spain (Program ID 042-12, 164-12) using the
EMIR heterodyne receiver in dual band observation mode in the
E0(90GHz)/E2(230GHz) configuration; the Atacama Pathfinder
EXperiment(APEX) 12m telescope on the Chajnantor Plateau, Chile
(Program ID 090.D-0290, 091.D-0813, 094.D-0851A), in the SHeFI 230GHz
band, and the Caltech Submillimeter Observatory (CSO) at Mauna Kea,
Hawaii, using the 230GHz receiver. The sources were observed using
position switching or wobbler switching mode to attain flat baselines.
The pointing of the telescope was checked repeatedly throughout the
observations using strong CO and continuum sources. The reduction and
analysis of all data were performed using the GILDAS CLASS software
package. After removing faulty scans and spikes, a firstorder
polynomial baseline was subtracted from each scan. The individual
baseline-subtracted scans obtained for a given source were then
averaged using an inverse quadratic system temperature weighting.
Finally the data were rebinned to obtain a suitable signal-to-noise
ratio (S/N), generally S/N=3-5 for a velocity resolution of 2km/s
(the typical linewidth being around 20-40km/s).
Objects:
----------------------------------------------------------
RA (ICRS) DE Designation(s)
----------------------------------------------------------
19 50 33.92 +32 54 50.6 chi Cyg = HD 187796
09 47 57.41 +13 16 43.6 CW Leo = PN G221.4+45.0
06 52 47.04 +08 25 19.1 GX Mon = SV* SON 4010
23 19 12.61 +17 11 33.1 LL Peg = PN G093.5-40.3
23 34 27.53 +43 33 01.2 LP And = RAFGL 3116
10 16 02.28 +30 34 19.0 RW LMi = PN G197.7+55.9
03 26 29.51 +47 31 48.6 V384 Per = SV* SVS 1809
19 15 23.35 -07 02 50.3 W Aql = RAFGL 2349
01 06 25.98 +12 35 53.0 WX Psc = PN G128.6-50.1
----------------------------------------------------------
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
list.dat 128 22 list of spectra
sp/* . 22 Individual spectrum fits files
--------------------------------------------------------------------------------
Byte-by-byte Description of file: list.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 F9.5 deg RAdeg Right Ascension of center (J2000)
10- 18 F9.5 deg DEdeg Declination of center (J2000)
20- 21 I2 --- Nx Number of pixels along X-axis
23- 45 A23 --- Obs.date Observation date (YYYY-MM-DDThh:mm:ss.sss)
47- 58 E12.6 Hz bFreq Lower value of frequency interval
60- 70 E11.6 Hz BFreq Upper value of frequency interval
72- 82 E11.6 Hz dFreq Frequency resolution
84 I1 Kibyte size Size of FITS file
86- 97 A12 --- FileName Name of FITS file, in subdirectory sp
99-128 A30 --- Title Title of the FITS file
--------------------------------------------------------------------------------
Acknowledgements:
Rutger De Nutte, rutger.denutte(at)ster.kuleuven.be
(End) Patricia Vannier [CDS] 09-Feb-2017