J/ApJ/794/81 Maser and infrared studies of oxygen-rich AGB stars (Yung+, 2014)
Maser and infrared studies of oxygen-rich late/post-asymptotic giant branch
stars and water fountains: development of a new identification method.
Yung B.H.K., Nakashima J.-I., Henkel C.
<Astrophys. J., 794, 81 (2014)>
=2014ApJ...794...81Y 2014ApJ...794...81Y (SIMBAD/NED BibCode)
ADC_Keywords: Masers ; Stars, giant ; Photometry, infrared
Keywords: infrared: stars - masers - stars: AGB and post-AGB -
stars: evolution - stars: winds, outflows
Abstract:
We explored an efficient method to identify evolved stars with
oxygen-rich envelopes in the late asymptotic giant branch (AGB) or
post-AGB phase of stellar evolution, which include a rare class of
objects - the "water fountains (WF)." Our method considers the OH and
H2O maser spectra, the near-infrared Q-parameters (these are color
indices accounting for the effect of extinction), and far-infrared
AKARI colors. Here we first present the results of a new survey on OH
and H2O masers. There were 108 color-selected objects: 53 of them
were observed in the three OH maser lines (1612, 1665, and 1667 MHz),
with 24 detections (16 new for 1612 MHz); and 106 of them were
observed in the H2O maser line (22 GHz), with 24 detections (12 new).
We identify a new potential WF source, IRAS 19356+0754, with large
velocity coverages of both OH and H2O maser emission. In addition,
several objects with high-velocity OH maser emission are reported for
the first time. The Q-parameters as well as the infrared [09]-[18] and
[18]-[65] AKARI colors of the surveyed objects are then calculated. We
suggest that these infrared properties are effective in isolating
aspherical from spherical objects, but the morphology may not
necessarily be related to the evolutionary status. Nonetheless, by
considering altogether the maser and infrared properties, the
efficiency of identifying oxygen-rich late/post-AGB stars could be
improved.
Description:
Most of the objects were selected from the AKARI Point Source
Catalogue (Kataza et al. 2010, Cat. II/298 ; Yamamura et al. 2010,
Cat. II/298), according to their [09]-[18] and [18]-[65] colors.
In Paper I (Yung et al. 2013, J/ApJ/769/20), we have defined the
empirical "post-AGB star" color region by 0.5≤[09]-[18]≤4.5 and
-0.5≤[18]-[65]≤2, where [m]-[n]=2.5log(Fn/Fm), with Fm and Fn
representing the band fluxes at m and n um, respectively. However,
this region still suffers from contamination by YSOs. Therefore, we
have also checked the mid-infrared images of all the objects during
the selection, in order to exclude obvious YSO candidates. The OH and
H2O maser observations were carried out with the Effelsberg 100 m
radio telescope from 2012 October 11 to 18. For the OH observations,
an 1.3-1.7 GHz HEMT receiver was used with a fast-Fourier-transform
(FFT) spectrometer as backend.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 95 108 Parameters of the Objects Observed
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See also:
II/298 : AKARI/FIS All-Sky Survey Point Source Catalogues
(ISAS/JAXA, 2010)
J/ApJ/769/20 : 22GHz H2O maser survey toward IR sources (Yung+, 2013)
J/ApJS/211/15 : SiO and H2O maser survey toward AGB + post-AGB stars
(Yoon+, 2014)
J/A+A/578/A119 : Water maser emission toward post-AGB and PN (Gomez+, 2015)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 16 A16 --- Name Object name (HHMMSSs+DDMMSS)
18- 42 A25 --- OName Other object name
44- 45 I2 h RAh Hour of Right Ascension (J2000)
47- 48 I2 min RAm Minute of Right Ascension (J2000)
50- 54 F5.2 s RAs Second of Right Ascension (J2000)
56 A1 --- DE- Sign of the Declination (J2000)
57- 58 I2 deg DEd Degree of Declination (J2000)
60- 61 I2 arcmin DEm Arcminute of Declination (J2000)
63- 66 F4.1 arcsec DEs Arcsecond of Declination (J2000)
68- 72 F5.2 --- AC12 ? AKARI [09]-[18] color
74- 78 F5.2 --- AC23 ? AKARI [18]-[65] color
80- 84 F5.2 --- Q1 ? Near-infrared Q1 parameter (1)
86- 91 F6.2 --- Q2 ? Near-infrared Q2 parameter (1)
93 A1 --- OH [YN-] Detection of OH maser emission in the
current observation (2)
95 A1 --- H2O [YN-] Detection of H2O maser emission in the
current observation (2)
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Note (1): Q1 and Q2 parameters are defined in Messineo et al.
(2012A&A...537A..10M 2012A&A...537A..10M); see Section 4.1.
Q1 is a measure of the deviation from the interstellar reddening vector in
the J-H versus H-Ks diagram,
Q2 is a measure of the deviation from the interstellar reddening vector in
the J-Ks versus Ks-[8.0] diagram.
Note (2): Maser emision as follows:
Y = detection ;
N = non-detection;
- = the object is not observed.
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History:
From electronic version of the journal
References:
Yung et al., Paper I, 2013ApJ...769...20Y 2013ApJ...769...20Y, J/ApJ/769/20
(End) Prepared by Tiphaine Pouvreau [CDS] 28-Apr-2017