MALT90 Kinematic Distances to Dense Molecular Clumps
- Physics Department, Boston University, 590 Commonwealth Avenue, Boston, MA 02215 (United States)
- Institute for Astrophysical Research, Boston University, Boston, MA 02215 (United States)
- CSIRO Astronomy and Space Science, P.O. Box 76, Epping NSW 1710 (Australia)
- Department of Astronomy, Yale University, P.O. Box 28101, New Haven, CT 06520-8101 (United States)
- Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden (Netherlands)
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.
- OSTI ID:
- 22663153
- Journal Information:
- Astronomical Journal (Online), Journal Name: Astronomical Journal (Online) Journal Issue: 4 Vol. 154; ISSN 1538-3881
- Country of Publication:
- United States
- Language:
- English
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