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Title: MALT90 Kinematic Distances to Dense Molecular Clumps

Abstract

Using molecular-line data from the Millimetre Astronomy Legacy Team 90 GHz Survey (MALT90), we have estimated kinematic distances to 1905 molecular clumps identified in the ATLASGAL 870 μ m continuum survey over the longitude range 295° <  l  < 350°. The clump velocities were determined using a flux-weighted average of the velocities obtained from Gaussian fits to the HCO{sup +}, HNC, and N{sub 2}H{sup +} (1–0) transitions. The near/far kinematic distance ambiguity was addressed by searching for the presence or absence of absorption or self-absorption features in 21 cm atomic hydrogen spectra from the Southern Galactic Plane Survey. Our algorithm provides an estimation of the reliability of the ambiguity resolution. The Galactic distribution of the clumps indicates positions where the clumps are bunched together, and these locations probably trace the locations of spiral arms. Several clumps fall at the predicted location of the far side of the Scutum–Centaurus arm. Moreover, a number of clumps with positive radial velocities are unambiguously located on the far side of the Milky Way at galactocentric radii beyond the solar circle. The measurement of these kinematic distances, in combination with continuum or molecular-line data, now enables the determination of fundamental parameters such as mass, size, and luminositymore » for each clump.« less

Authors:
 [1]; ; ;  [2];  [3];  [4];  [5];  [6]
  1. Physics Department, Boston University, 590 Commonwealth Avenue, Boston, MA 02215 (United States)
  2. Institute for Astrophysical Research, Boston University, Boston, MA 02215 (United States)
  3. CSIRO Astronomy and Space Science, P.O. Box 76, Epping NSW 1710 (Australia)
  4. Department of Astronomy, Yale University, P.O. Box 28101, New Haven, CT 06520-8101 (United States)
  5. Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden (Netherlands)
  6. Astrophysics Research Institute, Liverpool John Moores University, Egerton Wharf, Birkenhead CH41 1LD (United Kingdom)
Publication Date:
OSTI Identifier:
22663153
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astronomical Journal (Online); Journal Volume: 154; Journal Issue: 4; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ABSORPTION SPECTRA; ALGORITHMS; ASTRONOMY; CLOUDS; DISTANCE; GHZ RANGE; HYDROGEN; LUMINOSITY; MASS; MILKY WAY; RADIAL VELOCITY; RELIABILITY; RESOLUTION; SELF-ABSORPTION; STARS

Citation Formats

Whitaker, J. Scott, Jackson, James M., Sanhueza, Patricio, Stephens, Ian W., Rathborne, J. M., Foster, J. B., Contreras, Y., and Longmore, S. N., E-mail: scott@bu.edu. MALT90 Kinematic Distances to Dense Molecular Clumps. United States: N. p., 2017. Web. doi:10.3847/1538-3881/AA86AD.
Whitaker, J. Scott, Jackson, James M., Sanhueza, Patricio, Stephens, Ian W., Rathborne, J. M., Foster, J. B., Contreras, Y., & Longmore, S. N., E-mail: scott@bu.edu. MALT90 Kinematic Distances to Dense Molecular Clumps. United States. doi:10.3847/1538-3881/AA86AD.
Whitaker, J. Scott, Jackson, James M., Sanhueza, Patricio, Stephens, Ian W., Rathborne, J. M., Foster, J. B., Contreras, Y., and Longmore, S. N., E-mail: scott@bu.edu. Sun . "MALT90 Kinematic Distances to Dense Molecular Clumps". United States. doi:10.3847/1538-3881/AA86AD.
@article{osti_22663153,
title = {MALT90 Kinematic Distances to Dense Molecular Clumps},
author = {Whitaker, J. Scott and Jackson, James M. and Sanhueza, Patricio and Stephens, Ian W. and Rathborne, J. M. and Foster, J. B. and Contreras, Y. and Longmore, S. N., E-mail: scott@bu.edu},
abstractNote = {Using molecular-line data from the Millimetre Astronomy Legacy Team 90 GHz Survey (MALT90), we have estimated kinematic distances to 1905 molecular clumps identified in the ATLASGAL 870 μ m continuum survey over the longitude range 295° <  l  < 350°. The clump velocities were determined using a flux-weighted average of the velocities obtained from Gaussian fits to the HCO{sup +}, HNC, and N{sub 2}H{sup +} (1–0) transitions. The near/far kinematic distance ambiguity was addressed by searching for the presence or absence of absorption or self-absorption features in 21 cm atomic hydrogen spectra from the Southern Galactic Plane Survey. Our algorithm provides an estimation of the reliability of the ambiguity resolution. The Galactic distribution of the clumps indicates positions where the clumps are bunched together, and these locations probably trace the locations of spiral arms. Several clumps fall at the predicted location of the far side of the Scutum–Centaurus arm. Moreover, a number of clumps with positive radial velocities are unambiguously located on the far side of the Milky Way at galactocentric radii beyond the solar circle. The measurement of these kinematic distances, in combination with continuum or molecular-line data, now enables the determination of fundamental parameters such as mass, size, and luminosity for each clump.},
doi = {10.3847/1538-3881/AA86AD},
journal = {Astronomical Journal (Online)},
number = 4,
volume = 154,
place = {United States},
year = {Sun Oct 01 00:00:00 EDT 2017},
month = {Sun Oct 01 00:00:00 EDT 2017}
}