J/A+A/322/159 H2O maser emission from irregular variables (Szymczak+ 1997)
H2O maser emission from irregular variables
Szymczak M., Engels D.
<Astron. Astrophys. 322, 159 (1997)>
=1997A&A...322..159S 1997A&A...322..159S (SIMBAD/NED BibCode)
ADC_Keywords: Stars, variable ; Stars, masers
Keywords: masers - stars: circumstellar matter - stars: mass-loss -
stars: AGB, post-AGB - radio lines: stars
Abstract:
We have performed a search for the 22 GHz water maser line among 72
optically identified irregular and semiregular red variables. New
detections were made of five stars, while only four of nine objects
previously known as maser sources were redetected. The probability for
the detection of H2O maser emission increases with V light
amplitude, and with H-K and K-[12] colours just as in regular Mira and
semiregular variables of SRa- and SRb-types. The detection rate of
water masers is about 25% for nearby Lb objects (D<400pc) in the
sample, comparable to that observed in the SRa and SRb stars. No
masers were detected in objects with mass loss rates
≤4x10-8M☉/yr. Maser luminosities are 1041-1043photons/s
similar to that of the bluest Miras and typical SRa and SRb stars
showing water maser emission. A comparison of our data on irregular
stars with those previously obtained on SRa and SRb variables suggests
that most radio and infrared properties are indistinguishable among
both classes of objects.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2 37 70 Upper limits for the undetected irregular and
semiregular stars
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Byte-by-byte Description of file: table2
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Bytes Format Units Label Explanations
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1- 10 A10 --- GCVS GCVS name
11- 12 A2 --- ref references for H2O detection (1)
13- 23 A11 --- IRAS IRAS name
24- 26 A3 --- Mtype Morphological type
28- 32 A5 "M/YY" Date Observation date
33- 35 F3.1 Jy 3sigma 3 sigma upper limit
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Note (1): References:
a: H2O maser (unpublished Effelsberg data)
b: H2O maser (Dickinson 1976ApJS...30..259D 1976ApJS...30..259D)
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Acknowledgements: Marian Szymczak <msz@.astro.uni.torun.pl>
(End) Patricia Bauer [CDS] 27-May-1997