Deep in the Fields of the Andromeda Halo: Discovery of the Pegasus VII Dwarf Galaxy in UNIONS
We present the newly discovered dwarf galaxy Pegasus VII (Peg VII), a member of the M31 subgroup which has been uncovered in the ri photometric catalogs from the Ultraviolet Near-Infrared Optical Northern Survey and confirmed with follow-up imaging from both the Canada–France–Hawaii Telescope and th...
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IOP Publishing
2025-01-01
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| Series: | The Astrophysical Journal |
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| Online Access: | https://doi.org/10.3847/1538-4357/adb4f3 |
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| author | Simon E. T. Smith Alan W. McConnachie Stephen Gwyn Christian R. Hayes Massimiliano Gatto Ken Chambers Jean-Charles Cuillandre Michael J. Hudson Eugene Magnier Nicolas Martin Julio Navarro |
| author_facet | Simon E. T. Smith Alan W. McConnachie Stephen Gwyn Christian R. Hayes Massimiliano Gatto Ken Chambers Jean-Charles Cuillandre Michael J. Hudson Eugene Magnier Nicolas Martin Julio Navarro |
| author_sort | Simon E. T. Smith |
| collection | DOAJ |
| description | We present the newly discovered dwarf galaxy Pegasus VII (Peg VII), a member of the M31 subgroup which has been uncovered in the ri photometric catalogs from the Ultraviolet Near-Infrared Optical Northern Survey and confirmed with follow-up imaging from both the Canada–France–Hawaii Telescope and the Gemini-North Telescope. This system has an absolute V -band magnitude of −5.7 ± 0.2 mag and a physical half-light radius of 177 ${}_{-34}^{+36}$ pc, which is characteristic of dynamically confirmed Milky Way satellite dwarf galaxies and about 5 times more extended than the most extended M31 globular clusters. Peg VII lies at a three-dimensional separation from M31 of 331 ${}_{-4}^{+15}$ kpc, and a significant elongation ( ϵ ∼ 0.5) toward the projected direction of M31 could be indicative of a past tidal interaction, but additional investigation into the orbit, star formation history, and whether any gas remains in the galaxy is needed to better understand the evolution of Peg VII. |
| format | Article |
| id | doaj-art-bd4c4ea36312451e8bcdf6fb6e4927ad |
| institution | OA Journals |
| issn | 1538-4357 |
| language | English |
| publishDate | 2025-01-01 |
| publisher | IOP Publishing |
| record_format | Article |
| series | The Astrophysical Journal |
| spelling | doaj-art-bd4c4ea36312451e8bcdf6fb6e4927ad2025-08-20T01:51:48ZengIOP PublishingThe Astrophysical Journal1538-43572025-01-0198315910.3847/1538-4357/adb4f3Deep in the Fields of the Andromeda Halo: Discovery of the Pegasus VII Dwarf Galaxy in UNIONSSimon E. T. Smith0https://orcid.org/0000-0002-6946-8280Alan W. McConnachie1https://orcid.org/0000-0003-4666-6564Stephen Gwyn2https://orcid.org/0000-0001-8221-8406Christian R. Hayes3https://orcid.org/0000-0003-2969-2445Massimiliano Gatto4https://orcid.org/0000-0003-4636-6457Ken Chambers5https://orcid.org/0000-0001-6965-7789Jean-Charles Cuillandre6https://orcid.org/0000-0002-3263-8645Michael J. Hudson7https://orcid.org/0000-0002-1437-3786Eugene Magnier8https://orcid.org/0000-0002-7965-2815Nicolas Martin9https://orcid.org/0000-0002-1349-202XJulio Navarro10https://orcid.org/0000-0003-3862-5076Department of Physics and Astronomy, University of Victoria , Victoria, BC V8P 1A1, Canada ; simonsmith@uvic.caDepartment of Physics and Astronomy, University of Victoria , Victoria, BC V8P 1A1, Canada ; simonsmith@uvic.ca; NRC Herzberg Astronomy and Astrophysics , 5071 West Saanich Road, Victoria, BC V9E 2E7, CanadaNRC Herzberg Astronomy and Astrophysics , 5071 West Saanich Road, Victoria, BC V9E 2E7, CanadaSpace Telescope Science Institute , 3700 San Martin Drive, Baltimore, MD 21218, USAINAF—Osservatorio Astronomico di Capodimonte , Via Moiariello 16, I-80131 Naples, ItalyInstitute for Astronomy, University of Hawaii , 2680 Woodlawn Drive, Honolulu, HI 96822, USAAIM, CEA, CNRS, Université Paris-Saclay , Université Paris, F-91191 Gif-sur-Yvette, FranceDepartment of Physics and Astronomy, University of Waterloo , 200 University Ave W, Waterloo, ON N2L 3G1, Canada; Waterloo Centre for Astrophysics, University of Waterloo , 200 University Ave W, Waterloo, ON N2L 3G1, Canada; Perimeter Institute for Theoretical Physics , 31 Caroline St. North, Waterloo, ON N2L 2Y5, CanadaInstitute for Astronomy, University of Hawaii , 2680 Woodlawn Drive, Honolulu, HI 96822, USAUniversité de Strasbourg , CNRS, Observatoire Astronomique de Strasbourg, UMR 7550, F-67000 Strasbourg, France; Max-Planck-Institut für Astronomie , Königstuhl 17, D-69117 Heidelberg, GermanyDepartment of Physics and Astronomy, University of Victoria , Victoria, BC V8P 1A1, Canada ; simonsmith@uvic.caWe present the newly discovered dwarf galaxy Pegasus VII (Peg VII), a member of the M31 subgroup which has been uncovered in the ri photometric catalogs from the Ultraviolet Near-Infrared Optical Northern Survey and confirmed with follow-up imaging from both the Canada–France–Hawaii Telescope and the Gemini-North Telescope. This system has an absolute V -band magnitude of −5.7 ± 0.2 mag and a physical half-light radius of 177 ${}_{-34}^{+36}$ pc, which is characteristic of dynamically confirmed Milky Way satellite dwarf galaxies and about 5 times more extended than the most extended M31 globular clusters. Peg VII lies at a three-dimensional separation from M31 of 331 ${}_{-4}^{+15}$ kpc, and a significant elongation ( ϵ ∼ 0.5) toward the projected direction of M31 could be indicative of a past tidal interaction, but additional investigation into the orbit, star formation history, and whether any gas remains in the galaxy is needed to better understand the evolution of Peg VII.https://doi.org/10.3847/1538-4357/adb4f3Dwarf galaxiesLocal Group |
| spellingShingle | Simon E. T. Smith Alan W. McConnachie Stephen Gwyn Christian R. Hayes Massimiliano Gatto Ken Chambers Jean-Charles Cuillandre Michael J. Hudson Eugene Magnier Nicolas Martin Julio Navarro Deep in the Fields of the Andromeda Halo: Discovery of the Pegasus VII Dwarf Galaxy in UNIONS The Astrophysical Journal Dwarf galaxies Local Group |
| title | Deep in the Fields of the Andromeda Halo: Discovery of the Pegasus VII Dwarf Galaxy in UNIONS |
| title_full | Deep in the Fields of the Andromeda Halo: Discovery of the Pegasus VII Dwarf Galaxy in UNIONS |
| title_fullStr | Deep in the Fields of the Andromeda Halo: Discovery of the Pegasus VII Dwarf Galaxy in UNIONS |
| title_full_unstemmed | Deep in the Fields of the Andromeda Halo: Discovery of the Pegasus VII Dwarf Galaxy in UNIONS |
| title_short | Deep in the Fields of the Andromeda Halo: Discovery of the Pegasus VII Dwarf Galaxy in UNIONS |
| title_sort | deep in the fields of the andromeda halo discovery of the pegasus vii dwarf galaxy in unions |
| topic | Dwarf galaxies Local Group |
| url | https://doi.org/10.3847/1538-4357/adb4f3 |
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