J/ApJ/926/186 GASKAP pilot survey science. II. 21cm abs. (Dickey+, 2022)
GASKAP Pilot Survey Science.
II. ASKAP Zoom Observations of Galactic 21cm Absorption.
Dickey J.M., Dempsey J.M., Pingel N.M., McClure-Griffiths N.M.,
Jameson K., Dawson J.R., Denes H., Clark S.E., Joncas G., Leahy D.,
Lee M.-Y., Miville-Deschenes M.-A., Stanimirovic S., Tremblay C.D.,
van Loon J.T.
<Astrophys. J., 926, 186 (2022)>
=2022ApJ...926..186D 2022ApJ...926..186D
ADC_Keywords: Interstellar medium; Radio lines; Milky Way
Keywords: Diffuse interstellar clouds ; Intercloud medium ;
Interstellar absorption ; Interstellar atomic gas ;
Interstellar phases
Abstract:
Using the Australian Square Kilometre Array Pathfinder to measure 21cm
absorption spectra toward continuum background sources, we study the
cool phase of the neutral atomic gas in the far outer disk, and in the
inner Galaxy near the end of the Galactic bar at longitude 340°.
In the inner Galaxy, the cool atomic gas has a smaller scale height
than in the solar neighborhood, similar to the molecular gas and the
super-thin stellar population in the bar. In the outer Galaxy, the
cool atomic gas is mixed with the warm, neutral medium, with the cool
fraction staying roughly constant with the Galactic radius. The ratio
of the emission brightness temperature to the absorption, i.e.,
1-e-τ, is roughly constant for velocities corresponding to
Galactic radius greater than about twice the solar circle radius. The
ratio has a value of about 300K, but this does not correspond to a
physical temperature in the gas. If the gas causing the absorption has
kinetic temperature of about 100K, as in the solar neighborhood, then
the value 300 K indicates that the fraction of the gas mass in this
phase is one-third of the total HI mass.
Description:
The observations were taken as part of the Pilot phase 1 survey
science program on the Australian Square Kilometre Array Pathfinder
(ASKAP) on 2020 April 26 and 27 with total integration time of 16hr
(SBID 13531 and 13536).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table4.dat 88 105 Galactic sources
table5.dat 71 190 Extragalactic sources
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See also:
B/psr : ATNF Pulsar Catalogue (Manchester+, 2005)
VIII/76 : Leiden/Argentine/Bonn (LAB) Survey of Galactic HI (Kalberla+ 2005)
VII/284 : A Catalogue of Galactic Supernova Remnants (Green, 2019)
J/A+AS/76/317 : Possible new PNe in IRAS PSC (Preite-Martinez, 1988)
J/A+A/275/67 : Velocity Field of the outer Galaxy (Brand+ 1993)
J/ApJ/649/759 : Bubbles in the galactic disk (Churchwell+, 2006)
J/ApJ/783/130 : Parallaxes of high mass star forming regions (Reid+, 2014)
J/ApJ/793/132 : Perseus cloud sources Gaussian param. (Stanimirovic+, 2014)
J/A+A/568/A41 : ATLASGAL Compact Source Catalog: 280<l<60 (Urquhart+, 2014)
J/ApJS/212/1 : The WISE catalog of Galactic HII regions (Anderson+, 2014)
J/ApJS/221/26 : Radio obs. of Galactic WISE HII regions (Anderson+, 2015)
J/A+A/594/A116 : HI4PI spectra and column density maps (HI4PI team+, 2016)
J/ApJ/831/124 : Milky Way kinematics. II. (McClure-Griffiths+, 2016)
J/ApJ/834/57 : MW molecular clouds from 12CO (Miville-Deschenes+, 2017)
J/ApJS/238/14 : 21-SPONGE HI Absorption Line Survey. I. (Murray+, 2018)
J/ApJ/856/52 : Kinematic distances of star-forming regions (Wenger+, 2018)
J/ApJS/244/7 : ATCA HI abs. survey in Magellanic clouds. I. (Jameson+, 2019)
J/ApJ/880/141 : Arecibo 21cm obs. of sources in 5 GMC regions (Nguyen+, 2019)
J/ApJ/885/131 : ∼200 high-mass SFR plx & proper motion with VLBI (Reid+, 2019)
J/ApJ/887/114 : VLA ∼8-10GHz obs. of WISE Galactic HII regions (Wenger+, 2019)
J/ApJ/899/15 : Parameters for the 58 τHI(v) sightlines (Murray+, 2020)
J/ApJ/910/131 : Molecular gas distribution from MWISP CO survey (Su+, 2021)
Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- Seq [3/331] Index number
5- 6 I2 h RAh Hour of right ascension (J2000)
8- 9 I2 min RAm Minute of right ascension (J2000)
11- 14 F4.1 s RAs Second of right ascension (J2000)
16 A1 --- DE- Sign of declination (J2000)
17- 18 I2 deg DEd Degree of declination (J2000)
20- 21 I2 arcmin DEm Arcminute of declination (J2000)
23- 24 I2 arcsec DEs Arcsecond of declination (J2000)
26- 32 F7.3 deg GLON [336.36/344.23] Galactic longitude
34- 39 F6.3 deg GLAT [-3.12/1.62] Galactic latitude
41- 45 F5.3 --- Tau [0.004/0.81] Optical depth noise,στ
47- 64 A18 --- OType Object type identification (1)
66- 88 A23 --- Strct Structure (2)
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Note (1): Object type as follows:
WISE-H II = HII regions selected from the WISE survey
(Anderson+ 2014, J/ApJS/212/1 ; 51+8 occurrences)
ATLASgal = submillimeter compact sources from ATLASGAL
(Urquhart+ 2014, J/A+A/568/A41 ; 18+1+51 occurrences)
YSO = young stellar object (12 occurrences)
YSO? = young stellar object candidate (2 occurrences)
SNR = supernova remnants in Green 2019, VII/284
(5+1 occurrences)
Planetary Nebula = planetary nebulae from Riggi+ 2021, J/MNRAS/502/60 and
Preite-Martinez 1988, J/A+AS/76/317 (3 occurrences)
IR emission lines? = (1 occurrence)
S36 bubble = source on the rim of the S36 bubble
(Churchwell+ 2006, J/ApJ/649/759 ; 1 occurrence)
SF cloud = (1 occurrence)
darck cloud = (1 occurrence)
pulsar = pulsar (Manchester+ 2005, see B/psr) (1 occurrence)
See Section 2.1.
Note (2): Structure as:
complex structure = 45 occurrences;
point = 45 occurrences;
ring or shell source = 8 occurrences;
mean of a double source = 4 occurrences;
one component of double = 3 occurrences
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Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- Seq [0/346] Index number
5- 6 I2 h RAh Hour of right ascension (J2000)
8- 9 I2 min RAm Minute of right ascension (J2000)
11- 14 F4.1 s RAs Second of right ascension (J2000)
16 A1 --- DE- Sign of declination (J2000)
17- 18 I2 deg DEd Degree of declination (J2000)
20- 21 I2 arcmin DEm Arcminute of declination (J2000)
23- 24 I2 arcsec DEs Arcsecond of declination (J2000)
26- 32 F7.3 deg GLON [336.6/344] Galactic longitude
34- 39 F6.3 deg GLAT [-3.4/3.4] Galactic latitude
41- 45 F5.3 --- Tau [0.01/0.5] Optical depth noise, στ
47- 71 A25 --- Strct Structure (1)
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Note (1): Structure as:
single component = 150 occurrences
one component of a double = 18 occurrences
complex structure = 13 occurrences
mean of a double source = 9 occurrences
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History:
From electronic version of the journal
(End) Emmanuelle Perret [CDS] 03-Nov-2023