J/A+A/578/A119 Water maser emission toward post-AGB and PN (Gomez+, 2015)
A search for water maser emission toward obscured post-AGB star and planetary
nebula candidates.
Gomez J.F., Rizzo J.R., Suarez O., Palau A., Miranda L.F., Guerrero M.A.,
Ramos-Larios G., Torrelles J.M.
<Astron. Astrophys., 578, A119-119 (2015)>
=2015A&A...578A.119G 2015A&A...578A.119G (SIMBAD/NED BibCode)
ADC_Keywords: Masers ; Stars, giant ; Planetary nebulae
Keywords: masers - surveys - stars: AGB and post-AGB - stars: mass-loss -
planetary nebulae: general
Abstract:
Water maser emission at 22GHz is a useful probe for studying the
transition between the nearly spherical mass loss in the asymptotic
giant branch (AGB) to a collimated one in the post-AGB phase. In their
turn, collimated jets in the post-AGB phase could determine the shape
of planetary nebulae once photoionization starts. We intend to find
new cases of post-AGB stars and planetary nebulae (PNe) with water
maser emission, including some especially interesting and rare types:
water fountains (evolved objects with high velocity collimated jets
traced by water masers) or water-maser-emitting PNe. Since previous
studies have shown a higher detection rate of water maser emission in
evolved objects that are optically obscured, we selected a sample that
contains a significant fraction of post-AGB and young PN candidate
sources showing signs of strong obscuration. We searched for water
maser emission in 133 evolved objects using the radio telescopes in
Robledo de Chavela, Parkes, and Green Bank. We detected water maser
emission in 15 sources of our sample, of which seven are reported here
for the first time (IRAS 13483-5905, IRAS 14249-5310, IRAS 15408-5413,
IRAS 17021-3109, IRAS 17348-2906, IRAS 17393-2727, and
IRAS 18361-1203). We identified three water fountain candidates:
IRAS 17291-2147, with a total velocity spread of ≃96km/s in its water
maser components and two sources (IRAS 17021-3109 and IRAS 17348-2906)
that show water maser emission whose velocity lies outside the
velocity range covered by OH masers. We have also identified
IRAS 17393-2727 as a possible new water-maser-emitting PN. The
detection rate is higher in obscured objects (14%) than in those with
optical counterparts (7%), which is consistent with previous results.
Water maser emission seems to be common in objects that are bipolar in
the near-IR (43% detection rate in such sources). The water maser
spectra of water fountain candidates like IRAS 17291-2147 show
significantly fewer maser components than others (e.g.,
IRAS 18113-2503). We speculate that most post-AGBs may show water
maser emission with wide enough velocity spread (≥100km/s) when
observed with enough sensitivity and/or for long enough periods of
time. Therefore, it may be necessary to single out a special group of
"water fountains", probably defined by their high maser
luminosities. We also suggest that the presence of both water and OH
masers in a PN is a better tracer of its youth, than is the presence
of just one of these species.
Description:
The observed sources are listed in Table 1. They comprise most of the
sources in Ramos-Larios et al. (2009A&A...501.1207R 2009A&A...501.1207R). They are
post-AGB stars and PN candidates with the IRAS color criteria of
Suarez et al. (2006A&A...458..173S 2006A&A...458..173S) and with signs of strong optical
obscuration. We have also included some optically visible post-AGB
stars from Suarez et al. (2006A&A...458..173S 2006A&A...458..173S) that were not included
in our previous water maser observations of Suarez et al.
(2007A&A...467.1085S 2007A&A...467.1085S, 2009A&A...505..217S 2009A&A...505..217S) or for which those
observations had poor sensitivity.
We observed the 616-523 transition of H2O
(rest frequency = 22235.08MHz) using three different telescopes: the
DSS-63 antenna (70m diameter) at the Madrid Deep Space Communications
Complex (MDSCC) near Robledo de Chavela (Spain), the 64m antenna at
the Parkes Observatory of the Australia Telescope National Facility
(ATNF), and the 100m Robert C. Byrd Green Bank Telescope (GBT) of the
National Radio Astronomy Observatory. The observed positions, rms
noise per spectral channel, and observing dates are listed in Table 1.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 91 157 Observed sources
table2.dat 74 19 Water maser detections
refs.dat 59 24 References
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See also:
J/A+A/458/173 : Optical spectroscopy of 253 IRAS sources (Suarez+, 2006)
J/ApJS/211/15 : SiO & H2O maser survey toward AGB + post-AGB stars (Yoon+ 2014)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 10 A10 --- IRAS IRAS name
12- 13 I2 h RAh Right ascension (J2000)
15- 16 I2 min RAm Right ascension (J2000)
18- 21 F4.1 s RAs Right ascension (J2000)
23 A1 --- DE- Declination sign (J2000)
24- 25 I2 deg DEd Declination (J2000)
27- 28 I2 arcmin DEm Declination (J2000)
30- 31 I2 arcsec DEs Declination (J2000)
33- 43 A11 "date" Date Observation date
44 A1 --- n_Date [g] Note (1)
46- 48 A3 --- Tel Telescope (2)
50- 55 F6.4 Jy rms One-sigma noise level per spectral channel
56 A1 --- l_S Limit flag (3σ upper limit) for
non-detections in previous observations
57- 63 F7.3 Jy S ? Previous water maser observations of the
sources reported in the literature
65- 70 F6.3 Jy e_S ? 2σ rms uncertainty on S
71 A1 --- n_S [f] Note on S (1)
73- 86 A14 --- r_S References for previous water maser
observations, in refs.dat file
87 A1 --- f_S [h] Note on Ref (1)
89- 91 A3 --- Img Visibility of sources in optical and
infrared images (3)
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Note (1): Notes as follows:
f = Migenes et al. (1999ApJS..123..487M 1999ApJS..123..487M) reported a water maser of 56Jy,
which was incorrectly labelled as IRAS 18434-0042. The maser is ∼2°
away from this infrared source and it is associated with the
star-forming region W43S instead.
g = We observed IRAS 19071+0857 with Robledo and GBT, but it was contaminated
by the strong maser emission from W49A, which spilled into the telescope
sidelobes. The reported detection by Yoon et al. (2014, Cat.
J/ApJS/211/15) is also most likely contaminated. The upper limit listed
in this table corresponds to observations taken with the Very Large Array
(Suarez et al., in prep.), which confirmed that the maser emission was
not associated with IRAS 19071+0857.
h = Labeled as 19375+2359 in Han et al. (1998, Cat. J/A+AS/127/181).
Note (2): Telescopes as follows:
GBT = Green Bank
PKS = Parkes
ROB = Robledo
VLA = Very Large Array
Note (3): Visibility of sources in optical and infrared images as follows:
V = sources with optical counterpart in the Digital Sky Survey (as mentioned
in Ramos-Larios et al., 2009A&A...501.1207R 2009A&A...501.1207R, 2012A&A...545A..20R 2012A&A...545A..20R), or
with optical spectrum in Suarez et al. (2006, Cat. J/A+A/458/173)
N = sources detected only at near-infrared wavelengths or longer
(Ramos-Larios et al., 2009A&A...501.1207R 2009A&A...501.1207R, 2012A&A...545A..20R 2012A&A...545A..20R)
M = sources detected only at mid-infrared wavelengths or longer
(Ramos-Larios et al., 2009A&A...501.1207R 2009A&A...501.1207R, 2012A&A...545A..20R 2012A&A...545A..20R)
O = sources with strong obscuration, based on their infrared colours
(Table 9 in Ramos-Larios et al., 2012A&A...545A..20R 2012A&A...545A..20R)
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- IRAS IRAS name
12- 17 F6.1 km/s Vpeak LSR velocity of the peak emission in
each spectrum
19- 21 F3.1 km/s e_Vpeak Uncertainty on Vpeak (channel width)
23- 28 F6.1 km/s Vmin Minimum LSR velocity of the detected emission
30- 35 F6.1 km/s Vmax Maximum LSR velocity of the detected emission
36 A1 --- Note [f] Note (1)
38- 44 F7.3 Jy Speak Flux density of the peak emission
46- 50 F5.3 Jy e_Speak rms uncertainty on Speak (2σ)
52- 57 F6.2 Jy.km/s SInt Velocity-integrated flux density of the
spectrum
59- 62 F4.2 Jy.km/s e_SInt rms uncertainty on SInt (2σ)
64- 74 A11 "date" Date Observation date
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Note (1): f = There is detected emission very close to the redshifted edge of
the bandpass, so we probably missed some components beyond that edge.
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Byte-by-byte Description of file: refs.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 2 I2 --- Ref Reference number
4- 22 A19 --- BibCode BibCode
24- 39 A16 --- Aut Author's name
41- 59 A19 --- Com Comments
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 23-Sep-2015