Purpose of the Program

The nearby galaxy M51 was surveyed for [C II] emisison using FIFI-LS (to get a sensitive map of the line intensity) and GREAT (to get velocity-resolved emission profiles at each position). All calibrated data products are available here in the IRSA/SOFIA archive.

Co-Principal Investigators

Juergen Stutzki (University of Cologne), Jorge Pineda (JPL)

Proposal ID and Data Access


Proposal Abstract

We propose to obtain the first complete, velocity resolved [CII] 158um image of the M51 grand-design spiral galaxy with the upGREAT and FIFI-LS instruments on SOFIA. Spiral density waves play a fundamental role on the conversion of atomic to molecular gas, leading to gravitational contraction and thus to star formation. Understanding the impact of spiral density waves on the lifecycle of the interstellar medium and on star formation in galaxies is thus critical for our understanding of galaxy evolution. The [CII] line (in combination with the low-J CO lines and HI 21 cm) is an important tool to diagnose the physical state of the ISM. It can reveal the distribution of the gas that is making a transition between atomic and molecular phases, including the CO-dark H2 gas (hydrogen molecular but carbon ionized, and thus not traced by either HI or CO) in the spiral arms and interarm regions of M51. We will use the high spectral resolution of the upGREAT instrument to resolve spiral arms in velocity, allowing us to study the flow of gas through spiral arms and measure line widths and determine the dynamical state of prominent interarm clouds. The significantly more sensitive FIFI-LS will be used to detect extended faint [CII] emission in the interarm regions and outskirts of the galaxy, including the gas connection to the companion galaxy. The 3-D data cube of velocity--resolved [CII] in this nearby galaxy, combined with the wealth of ancillary data, can be used for a large set of investigations by the broader astronomical community. It will provide for the first time the link between the detailed physical processes in the star-forming ISM in the Milky Way and the average properties of distant external galaxies. This complete map will be also an excellent showcase of SOFIA's capabilities for years to come.


J. L. Pineda, J. Stutzki, C. Buchbender, J. Koda, C. Fischer, P. F. Goldsmith, S. C. O. Glover, R. S. Klessen, C. Kramer, B. Mookerjea, R. Smith, R. Treß, and M. Ziebart, A SOFIA Survey of [C II] in the Galaxy M51. II. [C II] and CO Kinematics across the Spiral Arms. The Astrophysical Journal 900, 132 (2020). [DOI]

J. L. Pineda, C. Fischer, M. Kapala, J. Stutzki, C. Buchbender, P. F. Goldsmith, M. Ziebart, S. C. O. Glover, R. S. Klessen, J. Koda, C. Kramer, B. Mookerjea, K. Sandstrom, N. Scoville, and R. Smith, A SOFIA Survey of [C II] in the Galaxy M51. I. [C II] as a Tracer of Star Formation. The Astrophysical Journal 869, L30 (2018). [DOI]