Sabrina Hurlock

East Tennessee State University, Johnson City, Tennessee, United States

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Publications (9)14.9 Total impact

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    ABSTRACT: Due to an error at the publisher, the name of the last author was accidentally omitted from the published article. The complete list of authors appears above. IOP Publishing sincerely regrets this error.
    The Astronomical Journal 05/2010; 139(6):2719. · 4.97 Impact Factor
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    ABSTRACT: We have used the GALEX ultraviolet telescope to study stellar populations and star formation morphology in a well-defined sample of 42 nearby optically-selected pre-merger interacting galaxy pairs. Galaxy interactions were likely far more common in the early Universe than in the present, thus our study provides a nearby well-resolved comparison sample for high redshift studies. We have combined the GALEX NUV and FUV images with broadband optical maps from the Sloan Digitized Sky Survey to investigate the ages and extinctions of the tidal features and the disks. The distributions of the UV/optical colors of the tidal features and the main disks of the galaxies are similar, however, the tidal features are bluer on average in NUV - g when compared with their own parent disks, thus tails and bridges are often more prominent relative to the disks in UV images compared to optical maps. This effect is likely due to enhanced star formation in the tidal features compared to the disks rather than reduced extinction, however, lower metallicities may also play a role. We have identified a few new candidate tidal dwarf galaxies in this sample. Other interesting morphologies such as accretion tails and `beads on a string' are also seen in these images. We also identify a possible `Taffy' galaxy in our sample, which may have been produced by a head-on collision between two galaxies. In only a few cases are strong tidal features seen in HI maps but not in GALEX. Comment: Accepted by the Astronomical Journal. Figures 1-18 in color jpg at http://www.etsu.edu/physics/bsmith/research/sg/galex_SDSS/galex_SDSS.html
    01/2010;
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    ABSTRACT: We have used the GALEX ultraviolet telescope to study stellar populations and star formation morphology in a well-defined sample of more than three dozen nearby optically-selected pre-merger interacting galaxy pairs. We have combined the GALEX NUV and FUV images with broadband optical maps from the Sloan Digitized Sky Survey to investigate the ages and extinctions of the tidal features and the disks. We have identified a few new candidate tidal dwarf galaxies in this sample, as well as other interesting morphologies such as accretion tails, `beads on a string', and `hinge clumps'. In only a few cases are strong tidal features seen in HI maps but not in GALEX. Comment: To appear in the Proceedings of the Galaxy Wars: Stellar Populations and Star Formation in Interacting Galaxies Conference
    08/2009;
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    ABSTRACT: We present GALEX ultraviolet images from a survey of strongly interacting galaxy pairs, and compare with images at other wavelengths. The tidal features are particularly striking in the UV images. Numerous knots of star formation are visible throughout the disks and the tails and bridges. We also identify a possible `Taffy' galaxy in our sample, which may have been produced by a head-on collision between two disk galaxies. Comment: 4 pages, 10 figures, To appear in the Proceedings of the Galaxy Wars: Stellar Populations and Star Formation in Interacting Galaxies Conference
    08/2009;
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    ABSTRACT: Tidal Dwarf Galaxies (TDG), concentrations of interstellar gas and stars in the tidal features of interacting galaxies, have been the subject of much scrutiny. The `smoking gun' that will prove the TDG hypothesis is the discovery of independent dwarf galaxies that are detached from other galaxies, but have clear tidal histories. As part of a search for TDGs we are using GALEX to conduct a large UV imaging survey of interacting galaxies selected from the Arp Atlas. As part of that study, we present a GALEX UV and SDSS and SARA optical study of the gas-rich interacting galaxy pair Arp 305. The GALEX UV data reveal much extended diffuse UV emission and star formation outside the disks including a candidate TDG between the two galaxies. We have used a smooth particle hydrodynamics code to model the interaction and determine the fate of the candidate TDG. Comment: 6 pages, 2 figures, to be published in the Proceedings of the `Galaxy Wars: Stellar Populations and Star Formation in Interacting Galaxies Conference'
    08/2009;
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    ABSTRACT: To search for Tidal Dwarf Galaxies (TDGs) and to study star formation in tidal features, we are conducting a large UV imaging survey of interacting galaxies selected from the Arp (1996) Atlas using the GALEX telescope. As part of that study, we present a GALEX UV and SDSS and SARA optical study of the gas-rich interacting galaxy pair Arp 305 (NGC 4016/7). The GALEX UV data reveal much extended diffuse UV emission and star formation outside the disks. This includes a luminous star forming region between the two galaxies, and a number of such regions in tidal tails. We have identified 45 young star forming clumps in Arp 305, including several TDG candidates. By comparing the UV and optical colors to population synthesis models, we determined that the clumps are very young, with several having ages of about 6 Myr. We do not find many intermediate age clumps in spite of the fact that the last closest encounter was about 300 Myr ago. We have used a smooth particle hydrodynamics code to model the interaction and determine the fate of the star clusters and candidate TDGs.
    05/2009;
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    ABSTRACT: To search for Tidal Dwarf Galaxies (TDGs) and to study star formation in tidal features, we are conducting a large UV imaging survey of interacting galaxies selected from the Arp (1996) Atlas using the GALEX telescope. As part of that study, we present a GALEX UV and SDSS and SARA optical study of the gas-rich interacting galaxy pair Arp 305 (NGC 4016/7). The GALEX UV data reveal much extended diffuse UV emission and star formation outside the disks. This includes a luminous star forming region between the two galaxies, and a number of such regions in tidal tails. We have identified 45 young star forming clumps in Arp 305, including several TDG candidates. By comparing the UV and optical colors to population synthesis models, we determined that the clumps are very young, with several having ages of about 6 Myr. We do not find many intermediate age clumps in spite of the fact that the last closest encounter was about 300 Myr ago. We have used a smooth particle hydrodynamics code to model the interaction and determine the fate of the star clusters and candidate TDGs. Comment: 12 pages, 6 figures, and 5 tables. Accepted for publication in the Astronomical Journal
    The Astronomical Journal 04/2009; · 4.97 Impact Factor
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    Sabrina Hurlock, Beverly J. Smith, Mark Hancock
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    ABSTRACT: We analyze SARA (Southeastern Association for Research in Astronomy) optical images of twelve interacting galaxy systems selected from the Arp Atlas, and compare with GALEX (Galaxy Evolution Explorer) UV images and with Spitzer infrared (3.6 μm and 8.0 μm) images. Using SARA, we observe the galaxies in visible wavelengths including B, V, and R broadband filters and narrowband redshifted H® filters. By analysing these images, we are able to determine the effects that interaction has on the structure of the galaxy including the formation of bridges and tails, and where new star formation is occuring.
    Journal of the Southeastern Association for Research in Astronomy. 04/2008; 2:47-54.
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    ABSTRACT: We present Spitzer infrared, Galaxy Evolution Explorer UV, and Sloan Digitized Sky Survey and Southeastern Association for Research in Astronomy optical images of the peculiar interacting galaxy pair Arp 285 (NGC 2856/4), and compare with a new numerical model of the interaction. We estimate the ages of clumps of star formation in these galaxies using population synthesis models, carefully considering the uncertainties on these ages. This system contains a striking example of "beads on a string": a series of star-formation complexes ~1 kpc apart. These "beads" are found in a tail-like feature that is perpendicular to the disk of NGC 2856, which implies that it was formed from material accreted from the companion NGC 2854. The extreme blueness of the optical/UV colors and redness of the mid-infrared colors implies very young stellar ages (~4-20 Myr) for these star-forming regions. Spectral decomposition of these "beads" shows excess emission above the modeled stellar continuum in the 3.6 μm and 4.5 μm bands, indicating either contributions from interstellar matter to these fluxes or a second older stellar population. These clumps have –12.0 < M_B < –10.6, thus they are less luminous than most dwarf galaxies. Our model suggests that bridge material falling into the potential of the companion overshoots the companion. The gas then piles up at apogalacticon before falling back onto the companion, and star formation occurs in the pile-up. There was a time delay of ~500 Myr between the point of closest approach between the two galaxies and the initiation of star formation in this feature. A luminous (M_B ~ –13.6) extended (FWHM ~ 1.3 kpc) "bright spot" is visible at the northwestern edge of the NGC 2856 disk, with an intermediate stellar population (400-1500 Myr). Our model suggests that this feature is part of a expanding ripple-like "arc" created by an off-center ring-galaxy-like collision between the two disks.
    The Astronomical Journal 03/2008; · 4.97 Impact Factor

Publication Stats

58 Citations
14.90 Total Impact Points

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Institutions

  • 2008–2010
    • East Tennessee State University
      • Department of Physics and Astronomy
      Johnson City, Tennessee, United States
    • California Institute of Technology
      • Spitzer Science Center
      Pasadena, California, United States