A DEEPER LOOK AT LEO IV: STAR FORMATION HISTORY AND EXTENDED STRUCTURE
We present MMT/Megacam imaging of the Leo IV dwarf galaxy in order to investigate its structure and star formation history, and to search for signs of association with the recently discovered Leo V satellite. Based on parameterized fits, we find that Leo IV is round, with ϵ < 0.23 (at the 68% con...
| Main Authors: | , , , , , |
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| Other Authors: | |
| Format: | Article |
| Language: | en_US |
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IOP Publishing
2015
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| Online Access: | http://hdl.handle.net/1721.1/95689 |
| _version_ | 1826203771210825728 |
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| author | Sand, David J. Seth, Anil Olszewski, Edward W. Willman, Beth Zaritsky, Dennis Kallivayalil, Nitya |
| author2 | MIT Kavli Institute for Astrophysics and Space Research |
| author_facet | MIT Kavli Institute for Astrophysics and Space Research Sand, David J. Seth, Anil Olszewski, Edward W. Willman, Beth Zaritsky, Dennis Kallivayalil, Nitya |
| author_sort | Sand, David J. |
| collection | MIT |
| description | We present MMT/Megacam imaging of the Leo IV dwarf galaxy in order to investigate its structure and star formation history, and to search for signs of association with the recently discovered Leo V satellite. Based on parameterized fits, we find that Leo IV is round, with ϵ < 0.23 (at the 68% confidence limit) and a half-light radius of r[subscript h] [~ over -] 130 pc. Additionally, we perform a thorough search for extended structures in the plane of the sky and along the line of sight. We derive our surface brightness detection limit by implanting fake structures into our catalog with stellar populations identical to that of Leo IV. We show that we are sensitive to stream-like structures with surface brightness μ [subscript r] [< over ~] 29.6 mag arcsec[superscript –2], and at this limit we find no stellar bridge between Leo IV (out to a radius of ~0.5 kpc) and the recently discovered, nearby satellite Leo V. Using the color-magnitude fitting package StarFISH, we determine that Leo IV is consistent with a single age (~14 Gyr), single metallicity ([Fe/H] ~ –2.3) stellar population, although we cannot rule out a significant spread in these values. We derive a luminosity of MV = –5.5 ± 0.3. Studying both the spatial distribution and frequency of Leo IV's "blue plume" stars reveals evidence for a young (~2 Gyr) stellar population which makes up ~2% of its stellar mass. This sprinkling of star formation, only detectable in this deep study, highlights the need for further imaging of the new Milky Way satellites along with theoretical work on the expected, detailed properties of these possible "reionization fossils." |
| first_indexed | 2024-09-23T12:42:47Z |
| format | Article |
| id | mit-1721.1/95689 |
| institution | Massachusetts Institute of Technology |
| language | en_US |
| last_indexed | 2024-09-23T12:42:47Z |
| publishDate | 2015 |
| publisher | IOP Publishing |
| record_format | dspace |
| spelling | mit-1721.1/956892022-09-28T09:36:07Z A DEEPER LOOK AT LEO IV: STAR FORMATION HISTORY AND EXTENDED STRUCTURE Sand, David J. Seth, Anil Olszewski, Edward W. Willman, Beth Zaritsky, Dennis Kallivayalil, Nitya MIT Kavli Institute for Astrophysics and Space Research Kallivayalil, Nitya We present MMT/Megacam imaging of the Leo IV dwarf galaxy in order to investigate its structure and star formation history, and to search for signs of association with the recently discovered Leo V satellite. Based on parameterized fits, we find that Leo IV is round, with ϵ < 0.23 (at the 68% confidence limit) and a half-light radius of r[subscript h] [~ over -] 130 pc. Additionally, we perform a thorough search for extended structures in the plane of the sky and along the line of sight. We derive our surface brightness detection limit by implanting fake structures into our catalog with stellar populations identical to that of Leo IV. We show that we are sensitive to stream-like structures with surface brightness μ [subscript r] [< over ~] 29.6 mag arcsec[superscript –2], and at this limit we find no stellar bridge between Leo IV (out to a radius of ~0.5 kpc) and the recently discovered, nearby satellite Leo V. Using the color-magnitude fitting package StarFISH, we determine that Leo IV is consistent with a single age (~14 Gyr), single metallicity ([Fe/H] ~ –2.3) stellar population, although we cannot rule out a significant spread in these values. We derive a luminosity of MV = –5.5 ± 0.3. Studying both the spatial distribution and frequency of Leo IV's "blue plume" stars reveals evidence for a young (~2 Gyr) stellar population which makes up ~2% of its stellar mass. This sprinkling of star formation, only detectable in this deep study, highlights the need for further imaging of the new Milky Way satellites along with theoretical work on the expected, detailed properties of these possible "reionization fossils." 2015-02-26T20:30:52Z 2015-02-26T20:30:52Z 2010-07 2009-11 Article http://purl.org/eprint/type/JournalArticle 0004-637X 1538-4357 http://hdl.handle.net/1721.1/95689 Sand, David J., Anil Seth, Edward W. Olszewski, Beth Willman, Dennis Zaritsky, and Nitya Kallivayalil. “A DEEPER LOOK AT LEO IV: STAR FORMATION HISTORY AND EXTENDED STRUCTURE.” The Astrophysical Journal 718, no. 1 (July 1, 2010): 530–542. © 2010 The American Astronomical Society en_US http://dx.doi.org/10.1088/0004-637x/718/1/530 Astrophysical Journal Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. application/pdf IOP Publishing American Astronomical Society |
| spellingShingle | Sand, David J. Seth, Anil Olszewski, Edward W. Willman, Beth Zaritsky, Dennis Kallivayalil, Nitya A DEEPER LOOK AT LEO IV: STAR FORMATION HISTORY AND EXTENDED STRUCTURE |
| title | A DEEPER LOOK AT LEO IV: STAR FORMATION HISTORY AND EXTENDED STRUCTURE |
| title_full | A DEEPER LOOK AT LEO IV: STAR FORMATION HISTORY AND EXTENDED STRUCTURE |
| title_fullStr | A DEEPER LOOK AT LEO IV: STAR FORMATION HISTORY AND EXTENDED STRUCTURE |
| title_full_unstemmed | A DEEPER LOOK AT LEO IV: STAR FORMATION HISTORY AND EXTENDED STRUCTURE |
| title_short | A DEEPER LOOK AT LEO IV: STAR FORMATION HISTORY AND EXTENDED STRUCTURE |
| title_sort | deeper look at leo iv star formation history and extended structure |
| url | http://hdl.handle.net/1721.1/95689 |
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