J/MNRAS/471/3915 MALT-45, 44 GHz class I methanol masers (Jordan+, 2017)
MALT-45: A 7 mm survey of the southern Galaxy.
II. ATCA follow-up observations of 44 GHz class I methanol masers.
Jordan C.H., Walsh A.J., Breen S.L., Ellingsen S.P., Voronkov M.A.,
Hyland L.J.
<Mon. Not. R. Astron. Soc., 471, 3915-3954 (2017)>
=2017MNRAS.471.3915J 2017MNRAS.471.3915J (SIMBAD/NED BibCode)
ADC_Keywords: Surveys ; Milky Way ; Masers ; Radio lines
Keywords: masers - surveys - stars: formation - ISM: molecules -
Galaxy: structure - radio lines: ISM
Abstract:
We detail interferometric observations of 44GHz class I methanol
masers detected by MALT-45 (a 7mm unbiased auto-correlated
spectral-line Galactic-plane survey) using the Australia Telescope
Compact Array. We detect 238 maser spots across 77 maser sites. Using
high-resolution positions, we compare the class I CH3OH masers to
other star formation maser species, including CS (1-0), SiO v=0 and
the H53α radio-recombination line. Comparison between the
cross- and auto-correlated data has allowed us to also identify
quasi-thermal emission in the 44GHz class I methanol maser line. We
find that the majority of class I methanol masers have small spatial
and velocity ranges (<0.5pc and <5km/s), and closely trace the
systemic velocities of associated clouds. Using 870µm dust
continuum emission from the ATLASGAL survey, we determine clump masses
associated with class I masers, and find that they are generally
associated with clumps between 1000 and 3000M☉. For each class
I methanol maser site, we use the presence of OH masers and radio
recombination lines to identify relatively evolved regions of
high-mass star formation; we find that maser sites without these
associations have lower luminosities and preferentially appear towards
dark infrared regions.
Description:
Observations were conducted on 2013 September 7 and 8 by using the
ATCA.
The correlator was programmed in the 64M-32k mode, which provides
'zoom windows' for enhanced spectral resolution. In this mode, each
zoom window has a channel resolution of 32kHz over a bandwidth of
64MHz. This same correlator mode was used in the observations
detailed by Paper I (Jordan et al., 2015MNRAS.448.2344J 2015MNRAS.448.2344J); however,
unlike Paper I, these observations made use of 'stitched zooms':
rather than using individual zoom windows, multiple zooms may be
joined to increase the bandwidth over a spectral line, while
maintaining the same spectral resolution. Each spectral line in these
observations was observed with stitched zoom windows covering 96MHz
(except for the window containing H51α and C34S (1-0), which
covers 224MHz). For observations at 7mm, the 32kHz channel
resolution corresponds to a spectral resolution of approximately
0.21km/s per channel. The spectral lines observed are
identical to that of Paper I.
File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table2.dat 80 79 Observational targets for class I CH3OH masers
table3.dat 74 77 *Associations with each of the class I
CH3OH maser sites
tablea1.dat 103 288 Gaussian spectral fits for class I CH3OH
maser spots (including table 4)
tableb1.dat 140 99 Gaussian fits for the spectra of thermal lines
detected towards class I CH3OH maser sites.
tableb2.dat 56 34 *Gaussian fits for the spectra of H53α RRLs
detected towards class I CH3OH maser sites
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Note on table3.dat: Note that the presence of CS (1-0) is not listed, because
it is detected towards every source.
Note on tableb2.dat: If a maser site is not listed, then H53α emission
was not detected.
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See also:
J/MNRAS/448/2344 : MALT-45, a 7mm survey of the southern Galaxy (Jordan+, 2015)
Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 12 A12 --- Name1 Paper I site name, GLLL.ll+B.bb
13- 14 A2 --- n_Name1 [*+d ] Note on Name1 (1)
17- 30 A14 --- Name2 Refined site name, GLLL.lll+N.bbb (2)
32- 33 I2 h RAh Interferometric phase centre
right ascension (J2000)
35- 36 I2 min RAm Interferometric phase centre
right ascension (J2000)
38- 41 F4.1 s RAs Interferometric phase centre
right ascension (J2000)
43 A1 --- DE- Interferometric phase centre
declination sign (J2000)
44- 45 I2 deg DEd Interferometric phase centre
declination (J2000)
47- 48 I2 arcmin DEm Interferometric phase centre
declination (J2000)
50- 51 I2 arcsec DEs Interferometric phase centre
declination (J2000)
53- 62 A10 "date" Obs.date Date on which the site was observed
64- 65 I2 mJy rms Median Off-source image-plane median RMS noise
value for the self-calibrated cube
67 A1 --- l_Rad Limit flag on Rad
68- 69 I2 arcsec Rad ? Smallest radius of a circle to encompass
all emission of the site
72- 75 I4 km/s Vmin ? Lower value of velocity range (3)
77- 80 I4 km/s Vmax ? Upper value of velocity range (3)
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Note (1): Notes as follows:
* = sites not listed by Paper I (Jordan et al., 2015, J/MNRAS/448/2344),
but have class I CH3OH maser emission detected in these observations.
+ = sites designated as 'young'; see Section 4.1
d = sites that have large shifts induced by self-calibration;
see Section 2.1.1
Note (2): Refined site name, which is determined from the mean position of maser
spots within a single maser site. The refined site names are used throughout
this paper. A refined name is not supplied if no maser emission was detected
in this work.
Note (3): Velocity range of emission detected in auto-correlation data.
All maser sites were observed with an approximate local standard of rest
velocity coverage between -353 and 195km/s. Note that sites with a radius
of <1arcsec contain either only one maser spot, or spots very close together.
Sites without a specified radius were not detected in this work. Sites
without a velocity range were not detected in cross- or auto-correlation
(see Section 3).
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Byte-by-byte Description of file: table3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 14 A14 --- Name Refined region name, GLLL.lll+B.bbb
or GLLL.ll+B.bb
15- 16 A2 --- n_Name [+d ] Note on Name (1)
18- 19 I2 h RAh Centre of maser emission
right ascension (J2000)
21- 22 I2 min RAm Centre of maser emission
right ascension (J2000)
24- 27 F4.1 s RAs Centre of maser emission
right ascension (J2000)
29 A1 --- DE- Centre of maser emission
declination sign (J2000)
30- 31 I2 deg DEd Centre of maser emission declination (J2000)
33- 34 I2 arcmin DEm Centre of maser emission declination (J2000)
36- 40 F5.2 arcsec DEs Centre of maser emission declination (J2000)
42- 45 F4.1 kpc Dist Kinematic distance (Reid et al. 2009)
47- 49 F3.1 kpc e_Dist Kinematic distance error
51- 66 A16 ---- Assos Associations with other masers
within 1 arcmin (2)
68 A1 --- SiO [Y/N] Presence of SiO (1-0) v=0?
70 A1 --- CH3OH [Y/N] Presence of CH3OH 1.0.-0.0. A+?
72 A1 --- H53a [Y/N] Presence of H53α?
74 A1 --- C34S [Y/N] Presence of C34S (1-0)?
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Note (2): Associations with other masers, EGOs and ATLASGAL sources within
1arcmin of the centre position. If there is more than one of the same type
of emission, it is listed as a subscript.
M = 6.7GHz CH3OH maser from Caswell et al.
(2011MNRAS.417.1964C 2011MNRAS.417.1964C, Cat. VIII/96)
W = 22GHz H2O maser from any of Breen et al. (2010MNRAS.406.1487B 2010MNRAS.406.1487B);
Walsh et al. (2011, Cat. J/MNRAS/416/1764; 2014, Cat. J/MNRAS/442/2240)
S = 1612MHz OH maser from Sevenster et al. (1997, Cat. J/A+AS/124/509)
C = 1665 or 1667MHz OH maser from Caswell (1998MNRAS.297..215C 1998MNRAS.297..215C)
G = EGO from Cyganowski et al. (2008, Cat. J/AJ/136/2391)
A = ATLASGAL point source from Contreras et al. (2013, Cat. J/A+A/549/A45)
Note (1): Flag as follows:
+ = regions as 'young'; see Section 4.1
d = regions that have large shifts induced by self-calibration;
see Section 2.1.1
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Byte-by-byte Description of file: tablea1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 17 A17 --- Spot Spot name, GLLL.llll+B.bbbbA (1)
18 A1 --- n_Spot [*] * for spots manually fitted
(see Section 2.1.1)
19- 20 I2 h RAh Right ascension (J2000) (2)
22- 23 I2 min RAm Right ascension (J2000) (2)
25- 30 F6.3 s RAs Right ascension (J2000) (2)
32- 36 F5.3 s e_RAs Error on right ascension
38 A1 --- DE- Declination sign (J2000) (2)
39- 40 I2 deg DEd Declination (J2000) (2)
42- 43 I2 arcmin DEm Declination (J2000) (2)
45- 50 F6.3 arcsec DEs [] Declination (J2000) (2)
52- 56 F5.3 arcsec e_DEs Error on declination
57- 63 F7.3 Jy Speak Peak flux density (fitted Gaussian parameters)
65- 69 F5.3 Jy e_Speak Error on Speak
71- 78 F8.3 km/s Vpeak Peak velocity (fitted Gaussian parameters)
80- 84 F5.3 km/s e_Vpeak Error on peak velocity
86- 90 F5.3 km/s FWHM FWHM (fitted Gaussian parameters)
92- 96 F5.3 km/s e_FWHM Error on FWHM
97-103 F7.3 Jy.km/s Sint Integrated flux density of the Gaussian
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Note (1): In the case where there is more than one velocity component at exactly
the same location, the letter associated with the Galactic position is
incremented.
Note (2): fitted position for the Gaussian.
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Byte-by-byte Description of file: tableb1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 14 A14 --- Name Site name
16- 20 F5.3 K IntPeak1 ? CS (1-0) parameters, peak intensity (1)
22- 26 F5.3 K e_IntPeak1 ? CS (1-0) parameters, peak intensity error
28- 35 F8.3 km/s Vpeak1 ? CS (1-0) parameters, peak velocity
37- 41 F5.3 km/s e_Vpeak1 ? CS (1-0) parameters, peak velocity error
43- 47 F5.2 km/s FWHM1 ? CS (1-0) parameters, FWHM
49- 52 F4.2 km/s e_FWHM1 ? CS (1-0) parameters, FWHM error
53- 58 F6.3 K.km/s IntI1 ? CS (1-0) parameters, integrated intensity
60- 64 F5.3 K IntPeak2 ? SiO (1-0) v=0 parameters, peak intensity (1)
66- 70 F5.3 K e_IntPeak2 ? SiO (1-0) v=0 parameters,
peak intensity error
72- 78 F7.2 km/s Vpeak2 ? SiO (1-0) v=0 parameters, peak velocity
80- 83 F4.2 km/s e_Vpeak2 ? SiO (1-0) v=0 parameters,
peak velocity error
85- 89 F5.2 km/s FWHM2 ? SiO (1-0) v=0 parameters, FWHM
91- 94 F4.2 km/s e_FWHM2 ? SiO (1-0) v=0 parameters, FWHM error
96-100 F5.3 K.km/s IntI2 ? SiO (1-0) v=0 parameters,
integrated intensity
102-105 F4.2 K IntPeak3 ? CH3OH 10-0_0 parameters,
peak intensity (1)
107-110 F4.2 K e_IntPeak3 ? CH3OH 10-0_0 parameters,
peak intensity error
112-118 F7.2 km/s Vpeak3 ? CH3OH 10-0_0 parameters, peak velocity
120-123 F4.2 km/s e_Vpeak3 ? CH3OH 10-0_0 parameters,
peak velocity error
125-129 F5.2 km/s FWHM3 ? CH3OH 10-0_0 parameters, FWHM
131-134 F4.2 km/s e_FWHM3 ? CH3OH 10-0_0 parameters,, FWHM error
136-140 F5.3 K.km/s IntI3 ? CH3OH 10-0_0 parameters,
integrated intensity
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Note (1): If no Gaussian information is listed for an emission type,
it was not detected.
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Byte-by-byte Description of file: tableb2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 14 A14 --- Name Site name
16- 20 F5.3 K Ipeak Peak intensity (fitted Gaussian parameters)
22- 26 F5.3 K e_Ipeak Peak intensity error
28- 33 F6.2 km/s Vpeak Peak velocity (fitted Gaussian parameters)
35- 38 F4.2 km/s e_Vpeak Peak velocity error
40- 44 F5.2 km/s FWHM FWHM (fitted Gaussian parameters)
46- 49 F4.2 km/s e_FWHM FWHM error
51- 56 F6.3 K.km/s Iint Integrated intensity
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History:
From electronic version of the journal
References:
Jordan et al., Paper I 2015MNRAS.448.2344J 2015MNRAS.448.2344J, Cat. J/MNRAS/448/2344
(End) Patricia Vannier [CDS] 14-Jun-2020