Extragalactic abstracts - IRSA - California Institute of Technology
Extragalactic abstracts - IRSA - California Institute of Technology
Extragalactic abstracts - IRSA - California Institute of Technology
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Spitzer_Approved_<strong>Extragalactic</strong><br />
Mar 25, 10 16:24 Page 393/742<br />
Spitzer Space Telescope − General Observer Proposal #50454<br />
Mid−Infrared Imaging <strong>of</strong> the Taffy Colliding Galaxy Pairs UGC 813/6 and Arp 261<br />
Principal Investigator: Beverly Smith<br />
Institution: East Tennessee State University<br />
Technical Contact: Beverly Smith, East Tennessee State University<br />
Co−Investigators:<br />
Curt Struck, Iowa State University<br />
Mark Hancock, East Tennessee State University<br />
Mark Giroux, East Tennessee State University<br />
Jeong−Sun Hwang, Iowa State University<br />
Science Category: interacting/merging galaxies<br />
Observing Modes: IracMap MipsPhot<br />
Hours Approved: 4.0<br />
Abstract:<br />
In Taffy galaxies, a head−on collision between two gas−rich equal−mass galaxies<br />
has occurred, stripping out a large quantity <strong>of</strong> gas from the disks, and creating<br />
a radio continuum−bright bridge between the two galaxies. To better understand<br />
the physics <strong>of</strong> dust formation, excitation, and destruction, an examination <strong>of</strong><br />
the dust properties in these unusual systems would be useful. We propose to use<br />
Spitzer to obtain mid−infrared images <strong>of</strong> two candidate Taffy systems, UGC 813/6<br />
and Arp 261. We will use these images to search for dust associated with the<br />
bridge, and to test for PAH destruction or dust heating by shocks during the<br />
impact. We will compare the data for these two systems with archival Spitzer<br />
data for the first Taffy galaxy discovered, UGC 12914/5. We will also compare<br />
with results from a Spitzer imaging survey <strong>of</strong> nearby interacting galaxies that<br />
we have recently completed, and with numerical simulations <strong>of</strong> the collisions<br />
between the galaxies.<br />
Spitzer_Approved_<strong>Extragalactic</strong><br />
Printed_by_SSC<br />
Mar 25, 10 16:24 Page 394/742<br />
Spitzer Space Telescope − General Observer Proposal #50689<br />
SAINTS: Star Formation and the ISM in Nearby Tidal Streams<br />
Principal Investigator: Beverly Smith<br />
Institution: East Tennessee State University<br />
Technical Contact: Beverly Smith, East Tennessee State University<br />
Co−Investigators:<br />
Sarah Higdon, Georgia Southern University<br />
Mark Hancock, East Tennessee State University<br />
James Higdon, Georgia Southern University<br />
Curt Struck, Iowa State University<br />
Science Category: interacting/merging galaxies<br />
Observing Modes: IracMap IrsStare MipsPhot<br />
Hours Approved: 30.8<br />
Abstract:<br />
We propose to obtain high quality mid−infrared spectra <strong>of</strong> a sample <strong>of</strong> nearby<br />
tidal dwarf galaxies and tidal streams. At the present time, the properties <strong>of</strong><br />
the interstellar matter in tidal features are not well−known. We will determine<br />
the strengths <strong>of</strong> the PAH features relative to the dust continuum, the hardness<br />
<strong>of</strong> the ISRF from the [Ne III]/[Ne II] and [S IV]/[S III] line ratios, the<br />
quantity <strong>of</strong> warm molecular gas from the H2 lines, as well as the neon and sulfur<br />
abundances. We will compare these quantities to those <strong>of</strong> normal dwarf and spiral<br />
galaxies. We have already acquired considerable data for most <strong>of</strong> our sample,<br />
including Spitzer broadband images, GALEX UV images, optical images, and HI<br />
maps. Tidal features may contribute significantly to the intergalactic medium,<br />
and some may evolve into independent galaxies. Since interactions are more<br />
common at high redshift, studying nearby examples are important for interpreting<br />
the results <strong>of</strong> high redshift surveys.<br />
Thursday March 25, 2010 xgal_covers.txt<br />
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