HERACLES: THE HERA CO LINE EXTRAGALACTIC SURVEY

Journal Article · Mon Jun 15 04:00:00 EDT 2009 · Astronomical Journal (New York, N.Y. Online)

DOI:https://doi.org/10.1088/0004-6256/137/6/4670; COUNTRY OF INPUT: INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA)· OSTI ID:21255750

Leroy, Adam K; Walter, Fabian; Bigiel, Frank; Roussel, Helene ^[1]; Usero, Antonio; Brinks, Elias ^[2]; Weiss, Axel ^[3]; Kennicutt, Robert C ^[4]; Schuster, Karl-Friedrich; Wiesemeyer, H W ^[5]; Kramer, Carsten ^[6]

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1. Max-Planck-Institut fuer Astronomie, Koenigstuhl 17, D-69117, Heidelberg (Germany)
2. Centre for Astrophysics Research, University of Hertfordshire, Hatfield AL10 9AB (United Kingdom)
3. MPIfR, Auf dem Huegel 69, 53121, Bonn (Germany)
4. University of Cambridge, Institute of Astronomy, Madingley Road, Cambridge CB3 0HA (United Kingdom)
5. IRAM, 300 rue de la Piscine, 38406 St. Martin d'Heres (France)
6. IRAM, Avenida Divina Pastora 7, E-18012 Granada (Spain)

We present the Heterodyne Receiver Array CO Line Extragalactic Survey, an atlas of CO emission from 18 nearby galaxies that are also part of The H I Nearby Galaxy Survey and the Spitzer Infrared Nearby Galaxies Survey. We used the HERA multipixel receiver on the IRAM 30-m telescope to map the CO J = 2 {yields} 1 line over the full optical disk (defined by the isophotal radius r {sub 25}) of each target, at 13'' angular resolution and 2.6 km s{sup -1} velocity resolution. Here we describe the observations and reduction of the data and show channel maps, azimuthally averaged profiles, integrated intensity maps, and peak intensity maps. The implied H{sub 2} masses range from 7 x 10{sup 6} to 6 x 10{sup 9} M {sub sun}, with four low metallicity dwarf irregular galaxies yielding only upper limits. In the cases where CO is detected, the integrated H{sub 2}-to-H I ratios range from 0.02 to 1.13 and H{sub 2}-to-stellar mass ratios from 0.01 to 0.25. Exponential scale lengths of the CO emission for our targets are in the range 0.8-3.2 kpc, or 0.2 {+-} 0.05r {sub 25}. The intensity-weighted mean velocity of CO matches that of H I very well, with a 1{sigma} scatter of only 6 km s{sup -1}. The CO J = 2 {yields} 1/J = 1 {yields} 0 line ratio varies over a range similar to that found in the Milky Way and other nearby galaxies, {approx}0.6-1.0, with higher values found in the centers of galaxies. The typical line ratio, {approx}0.8, could be produced by optically thick gas with an excitation temperature of {approx}10 K.

• OSTI ID: 21255750
• Journal Information: Astronomical Journal (New York, N.Y. Online), Journal Name: Astronomical Journal (New York, N.Y. Online) Journal Issue: 6 Vol. 137; ISSN 1538-3881
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
99 GENERAL AND MISCELLANEOUS
EMISSION
HETERODYNE RECEIVERS
HYDROGEN
MAPS
MILKY WAY
RESOLUTION
TELESCOPES
VELOCITY