J/A+A/634/A83 THOR DR2 source list (Wang+, 2020)
The HI/OH/Recombination line survey of the inner Milky Way (THOR):
data release 2 and HI overview.
Wang Y., Beuther H., Rugel M.R., Soler J.D., Stil J.M., Ott J., Bihr S.,
McClure-Griffiths N.M., Anderson L.D., Klessen R.S., Goldsmith P.F.,
Roy N., Glover S.C.O., Urquhart J.S., Heyer M., Linz H., Smith R.J.,
Bigiel F., Dempsey J., Henning T.
<Astron. Astrophys. 634, A83 (2020)>
=2020A&A...634A..83W 2020A&A...634A..83W (SIMBAD/NED BibCode)
ADC_Keywords: Surveys ; Milky Way ; Radio sources ; Radio continuum
Keywords: ISM: clouds - ISM: atoms - ISM: molecules - radio lines: ISM -
stars: formation
Abstract:
The Galactic plane has been observed extensively by a large number of
Galactic plane surveys from infrared to radio wavelengths at an
angular resolution below 40". However, a 21cm line and continuum
survey with comparable spatial resolution is lacking.
The first half of THOR data (l=14.0°-37.9°, and
l=47.1°-51.2°, |b|≤1.25°) has been published in our data
release 1 paper. With this data release 2 paper, we publish all the
remaining spectral line data and Stokes I continuum data with high
angular resolution (10"-40"), including a new HI dataset for the
whole THOR survey region (l=14.0°-67.4° and |b|≤1.25°).
As we published the results of OH lines and continuum emission
elsewhere, we concentrate on the HI analysis in this paper
With the Karl G. Jansky Very Large Array (VLA) in C-configuration, we
observed a large portion of the first Galactic quadrant, achieving an
angular resolution of 40". At L Band, the WIDAR correlator at the VLA
was set to cover the 21cm HI line, four OH transitions, a series of
Hnα radio recombination lines (RRLs; n=151 to 186), and eight
128MHz-wide continuum spectral windows (SPWs), simultaneously.
We publish all OH and RRL data from the C-configuration observations,
and a new HI dataset combining VLA C+D+GBT (VLA D-configuration and
GBT data are from the VLA Galactic Plane Survey) for the whole survey.
The HI emission shows clear filamentary substructures at negative
velocities with low velocity crowding. The emission at positive
velocities is more smeared-out, likely due to higher spatial and
velocity crowding of structures at the positive velocities. Compared
to the spiral arm model of the Milky Way, the atomic gas follows the
Sagittarius and Perseus Arm well, but with significant material in the
inter-arm regions. With the C-configuration-only HI+continuum data, we
produced a HI optical depth map of the THOR areal coverage from 228
absorption spectra with the nearest-neighbor method. With this map, we
corrected the HI emission for optical depth, and the derived column
density is 38% higher than the column density with optically thin
assumption. The total HI mass with optical depth correction in the
survey region is 4.7x108M☉, 31% more than the mass derived
assuming the emission is optically thin. If we applied this 31%
correction to the whole Milky Way, the total atomic gas mass would be
9.4-10.5x109M☉. Comparing the HI with existing CO data, we
find a significant increase in the atomic-to-molecular gas ratio from
the spiral arms to the inter-arm regions.
The high-sensitivity and resolution THOR HI dataset provides an
important new window on the physical and kinematic properties of gas
in the inner Galaxy. Although the optical depth we derive is a lower
limit, our study shows that the optical depth correction is
significant for Hi column density and mass estimation. Together with
the OH, RRL and continuum emission from the THOR survey, these new HI
data provide the basis for high-angular-resolution studies of the
interstellar medium (ISM) in different phases.
Description:
In this paper, we publish the data from the second half of
the survey, including the new Hi dataset for the whole survey,
available at our project website (http://www.mpia.de/thor).
All fits data are available at :
http://www2.mpia-hd.mpg.de/thor/DATA/www
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 47 228 Optical depth measurements towards the selected
continuum sources
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See also:
J/A+A/580/A112 : THOR. The HI, OH, Recombination Line Survey (Bihr+, 2015)
J/A+A/588/A97 : Continuum sources from the THOR survey (Bihr+, 2016)
J/A+A/619/A124 : THOR survey in northern Galactic plane (Wang+, 2018)
J/A+A/628/A90 : OH maser emission in THOR survey (Beuther+, 2019)
http://www2.mpia-hd.mpg.de/thor/DATA/www : THOR Data Access
Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1- 13 A13 --- Name Name of the source (GLL.lll+B.bbb)
15- 18 I4 K Tcont Brightness temperature of the continuum source
20- 21 I2 K e_Tcont rms noise level of the brightness temperature
23- 25 F3.1 --- taulimit Lower limit of the optical depth
27- 29 I3 km/s inttau Integrated optical depth across the velocity
range (-128.5<vlsr<170 km/s)
31- 33 I3 --- Reff Effective radius of the source (1)
35- 47 A13 --- Note Note (2)
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Note (1): Effective radius Reff was calculated from the area of the source
assuming a circular shape.
Note (2): The physical nature of the continuum sources are taken from
Wang et al. (2018, Cat. J/A+A/619/A124).
HII = sources associated with HII regions from Anderson et al.
(2014, Cat. J/ApJS/212/1)
SNR_green = sources associated with SNRs from Green
(2014BASI...42...47G 2014BASI...42...47G, Cat. VII/272)
SNR_anderson = sources associated with SNR candidates from
Anderson et al. (2017, Cat. J/A+A/605/A58)
PN = sources classified as planetary nebula
Xray = sources associated with X-ray sources
jets = sources classified as extragalactic jets candidates.
The sources without a note in this column are most likely to be
extragalactic origin.
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Acknowledgements:
Yuan Wang, wang(at)mpia.de
(End) Patricia Vannier [CDS] 20-Dec-2019