J/MNRAS/442/2240 Accurate water maser positions from HOPS (Walsh+, 2014)
Accurate water maser positions from HOPS.
Walsh A.J., Purcell C.R., Longmore S.N., Breen S.L., Green J.A.,
Harvey-Smith L., Jordan C.H.
<Mon. Not. R. Astron. Soc. 442, 2240 (2014)>
=2014MNRAS.442.2240W 2014MNRAS.442.2240W
ADC_Keywords: Masers ; Radio lines ; Positional data
Keywords: masers - stars: formation - ISM: molecules
Abstract:
We report on high spatial resolution water maser observations, using
the Australia Telescope Compact Array, towards water maser sites
previously identified in the H2O southern Galactic Plane Survey (HOPS)
within the area covering Galactic coordinates from l=290 to l=30
and b=-0.5 to b=+0.5. Of the 540 maser sites identified in the
single-dish observations of Walsh et al. (2011MNRAS.416.1764W 2011MNRAS.416.1764W, Cat.
J/MNRAS/416/1764), we detect emission in all but 31 fields. These
maser sites together comprise 2790 individual spectral features (maser
spots), with brightnesses ranging from 0.06Jy to 576Jy and with
velocities ranging from -238.5 to +300.5km/s. Based on a definition of
maser site size of 4-arcsec (except for G000.667+0.028, also known as
Sgr B2, which we treat as a special case), we identify 631 maser
sites. We have compared the positions of these sites to the literature
to associate the sites with astrophysical objects. We identify 433
(69%) with star formation, 121 (19%) with evolved stars and 77 (12%)
as unknown. Comparing the properties of maser sites of different
origins, we find that those associated with evolved stars tend to have
more maser spots and have smaller angular sizes than those associated
with star formation. We present evidence that maser sites associated
with evolved stars show an increased likelihood of having a velocity
range between 15 and 35 km/s compared to other maser sites. We suggest
this is because many of these maser sites are associated with the
circumstellar shells of the evolved stars, which are expanding at
these velocities. Of the 31 non-detections, we conclude they were not
detected due to intrinsic variability and confirm previous results
showing that such variable masers tend to be weaker and have simpler
spectra with fewer peaks. Of the small number of maser sites showing
linear features, we find evidence for lines that are both
perpendicular and parallel to known outflows, suggesting that in star
formation, H2O maser origins may be as varied and as complex as
those of class II methanol masers.
Description:
Observations were made with the ATCA during three sessions: from 2011
March, 13th to 23rd, on 2012 April 2nd and from 2012 May 25th to 31st.
Configurations for the three sessions were 1.5A, H168 and 6D,
respectively.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 91 2790 Details of maser spots, based on ATCA observations
table3.dat 52 631 Associations with the water maser sites
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See also:
VIII/96 : 6-GHz methanol multibeam maser catalogue (Caswell+, 2010-12)
J/MNRAS/416/1764 : H2O Southern Galactic Plane Survey (HOPS) (Walsh+, 2011)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 14 A14 --- Name Name of maser site (GLLL.lll+B.bbb)
15- 16 A2 --- m_Name Name of maser spot (AA)
17 A1 --- n_Name [*] * indicates strongest spot in site
19- 20 I2 h RAh Right ascension (J2000.0)
22- 23 I2 min RAm Right ascension (J2000.0)
25- 30 F6.3 s RAs Right ascension (J2000.0)
32 A1 --- DE- Declination sign (J2000.0)
33- 34 I2 deg DEd Declination (J2000.0)
36- 37 I2 arcmin DEm Declination (J2000.0)
39- 44 F6.3 arcsec DEs Declination (J2000.0)
46- 52 F7.3 Jy Sp Peak flux density of H2O maser
54- 59 F6.1 km/s Vp Peak velocity of H2O maser
61- 66 F6.3 arcsec errMaj Relative uncertainty in position major axis
68- 73 F6.3 arcsec errMin Relative uncertainty in position minor axis
75- 79 F5.1 deg errPA [-90/90] Relative uncertainty and beam
position angle
81- 85 F5.2 arcsec Bmaj Synthesized beam major axis
87- 91 F5.2 arcsec Bmin Synthesized beam minor axis
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 14 A14 --- Name Name of maser site (GLLL.lll+B.bbb)
16 A1 --- Meth [Y/N] Association with Methanol maser ?
18 A1 --- NH3 [Y/N] Association with HOPS Ammonia ?
20- 26 A7 --- RMS Association based on RMS catalogue (1)
28- 32 A5 --- PapI Association based on HOPS Paper I,
Walsh et al. 2011 (J/MNRAS/416/1764)
34- 44 A11 --- GLIMPSE Association based on GLIMPSE images (2)
46- 52 A7 --- ASS-RES Assignment and Reason (3)
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Note (1): RMS sources are defined as follows:
YSO = young stellar object
HII = HII region
DHII = diffuse HII region
ES = evolved star
PN = planetary nebula
N = no association
? = a question mark means the association is not certain.
Note (2): GLIMPSE features are defined as follows:
IRDC = infrared dark cloud
EE = extended emission
BS = bright star (saturated in GLIMPSE point source catalog)
RS = red star
EGO = extended green object
R = red extended object
N = no clear association with a GLIMPSE feature
Note (3): Sources with unknown assignments are listed as U.
The rest of this column is formatted as "Assignment-Reason", where
* "Assignment" can be:
SF = star formation
ES = evolved star
cPN = candidate planetary nebula
* "Reason" can be:
MMB = methanol maser site, based on methanol multibeam data (Caswell et al.
2010MNRAS.404.1029C 2010MNRAS.404.1029C; Green et al. 2010MNRAS.409..913G 2010MNRAS.409..913G; Caswell et al.
2011MNRAS.417.9649C 2011MNRAS.417.9649C; Green et al. 2012MNRAS.420.3108G 2012MNRAS.420.3108G, Cat. VIII/96)
RMS = based on RMS identification (Lumsden et al. 2013ApJS..208...11L 2013ApJS..208...11L,
Cat. J/ApJS/208/11)
BGPS = based on Bolocam Galactic Plane Survey (Rosolowsky et al.
2010ApJS..188..123R 2010ApJS..188..123R, Cat. J/ApJS/188/123)
JCMT = based on JCMT SCUBA legacy identification (Di Francesco et al.
2008ApJS..175..277D 2008ApJS..175..277D, Cat. J/ApJS/175/277)
IRAS = based on IRAS spectrum identification (Kwok, Volk & Bidelman
1997ApJS..112..557K 1997ApJS..112..557K, Cat. J/ApJS/112/557)
PI = based on identification in Paper I (Walsh et al.
2011MNRAS.416.1764W 2011MNRAS.416.1764W, Cat. J/MNRAS/416/1764)
PRX = based on proximity to another water maser site with identification
HNS = based on identifications made in Hansen & Blanco
(1975AJ.....80.1011H 1975AJ.....80.1011H, Cat. J/AJ/80/1011)
WAL = Walsh et al. (1998MNRAS.301..640W 1998MNRAS.301..640W, Cat. J/MNRAS/301/640)
CYG = Cyganowski et al. (2009ApJ...702.1615C 2009ApJ...702.1615C, Cat. J/ApJ/702/1615)
DAV = Davies et al. (2007ApJ...671..781D 2007ApJ...671..781D, Cat. J/ApJ/671/781)
CHN = Chen & Yang (2012AJ....144..104C 2012AJ....144..104C)
SRZ = Suarez et al. (2009A&A...505..217S 2009A&A...505..217S)
TAP = Tapia et al. (1989A&A...225..488T 1989A&A...225..488T)
SEV = Sevenster et al. (1997A&AS..124..509S 1997A&AS..124..509S, Cat. J/A+AS/124/509)
CLK = Clark, Ritchie & Negueruela (2010A&A...514A..87C 2010A&A...514A..87C)
KIM = Kim, Cho & Kim (2013AJ....145...22K 2013AJ....145...22K, Cat. J/AJ/145/22)
SJW = Sjouwerman et al. (1998A&AS..128...35S 1998A&AS..128...35S, Cat. J/A+AS/128/35)
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Acknowledgements:
Andrew Walsh, andrew.walsh(at)curtin.edu.au
References:
Walsh et al., Paper I 2011MNRAS.416.1764W 2011MNRAS.416.1764W, Cat. J/MNRAS/416/1764
(End) Patricia Vannier [CDS] 24-Jun-2014