Deep Photometric Observations of Ultrafaint Milky Way Satellites Centaurus I and Eridanus IV
We present deep Magellan+Megacam imaging of Centaurus I (Cen I) and Eridanus IV (Eri IV), two recently discovered Milky Way ultrafaint satellites. Our data reach ∼2–3 mag deeper than the discovery data from the DECam Local Volume Exploration Survey. We use these data to constrain their distances, st...
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2025-01-01
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| author | Quinn O. Casey Burçin Mutlu-Pakdil David J. Sand Andrew B. Pace Denija Crnojević Amandine Doliva-Dolinsky William Cerny Mairead E. Heiger Alex H. Riley Alexander P. Ji Guilherme Limberg Laurella Marin Clara E. Martínez-Vázquez Gustavo E. Medina Ting S. Li Sasha N. Campana Astha Chaturvedi Joanna D. Sakowska Alfredo Zenteno Julio A. Carballo-Bello Mahdieh Navabi Clecio R. Bom (DELVE Collaboration) |
| author_facet | Quinn O. Casey Burçin Mutlu-Pakdil David J. Sand Andrew B. Pace Denija Crnojević Amandine Doliva-Dolinsky William Cerny Mairead E. Heiger Alex H. Riley Alexander P. Ji Guilherme Limberg Laurella Marin Clara E. Martínez-Vázquez Gustavo E. Medina Ting S. Li Sasha N. Campana Astha Chaturvedi Joanna D. Sakowska Alfredo Zenteno Julio A. Carballo-Bello Mahdieh Navabi Clecio R. Bom (DELVE Collaboration) |
| author_sort | Quinn O. Casey |
| collection | DOAJ |
| description | We present deep Magellan+Megacam imaging of Centaurus I (Cen I) and Eridanus IV (Eri IV), two recently discovered Milky Way ultrafaint satellites. Our data reach ∼2–3 mag deeper than the discovery data from the DECam Local Volume Exploration Survey. We use these data to constrain their distances, structural properties (e.g., half-light radii, ellipticity, and position angle), and luminosities. We investigate whether these systems show signs of tidal disturbance and identify new potential member stars using Gaia EDR3. Our deep color–magnitude diagrams show that Cen I and Eri IV are consistent with an old ( τ ∼ 13.0 Gyr) and metal-poor ([Fe/H] ≤ −2.2) stellar population. We find Cen I to have a half-light radius of ${r}_{h}=2.\,^{\prime} 60\pm 0.\,^{\prime} 30\,$ (90.6 ± 11 pc), an ellipticity of ϵ = 0.36 ± 0.05, a distance of D = 119.8 ± 4.1 kpc ( m − M = 20.39 ± 0.08 mag), and an absolute magnitude of M _V = −5.39 ± 0.19. Similarly, Eri IV has ${r}_{h}=3.\,^{\prime} 24\pm 0.\,^{\prime} 48\,$ (65.9 ± 10 pc), ϵ = 0.26 ± 0.09, D = 69.9 ± 3.6 kpc ( m − M = 19.22 ± 0.11 mag), and M _V = −3.55 ± 0.24. These systems occupy a space on the size–luminosity plane consistent with other known Milky Way dwarf galaxies, which supports the findings from our previous spectroscopic follow-up. Cen I has a well-defined morphology that lacks any clear evidence of tidal disruption, whereas Eri IV hosts a significant extended feature with multiple possible interpretations. |
| format | Article |
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| spelling | doaj-art-29b80e2d9df049fb8eff82eb121a86b82025-08-20T03:52:38ZengIOP PublishingThe Astrophysical Journal1538-43572025-01-01984214810.3847/1538-4357/adc67eDeep Photometric Observations of Ultrafaint Milky Way Satellites Centaurus I and Eridanus IVQuinn O. Casey0https://orcid.org/0009-0005-9002-4800Burçin Mutlu-Pakdil1https://orcid.org/0000-0001-9649-4815David J. Sand2https://orcid.org/0000-0003-4102-380XAndrew B. Pace3https://orcid.org/0000-0002-6021-8760Denija Crnojević4https://orcid.org/0000-0002-1763-4128Amandine Doliva-Dolinsky5https://orcid.org/0000-0001-9775-9029William Cerny6https://orcid.org/0000-0003-1697-7062Mairead E. Heiger7https://orcid.org/0000-0002-2446-8332Alex H. Riley8https://orcid.org/0000-0001-5805-5766Alexander P. Ji9https://orcid.org/0000-0002-4863-8842Guilherme Limberg10https://orcid.org/0000-0002-9269-8287Laurella Marin11https://orcid.org/0009-0008-3389-9848Clara E. Martínez-Vázquez12https://orcid.org/0000-0002-9144-7726Gustavo E. Medina13https://orcid.org/0000-0003-0105-9576Ting S. Li14https://orcid.org/0000-0002-9110-6163Sasha N. Campana15https://orcid.org/0009-0007-9488-7050Astha Chaturvedi16https://orcid.org/0000-0001-5143-1255Joanna D. Sakowska17https://orcid.org/0000-0002-1594-1466Alfredo Zenteno18https://orcid.org/0000-0001-6455-9135Julio A. Carballo-Bello19https://orcid.org/0000-0002-3690-105XMahdieh Navabi20https://orcid.org/0000-0001-9438-5228Clecio R. Bom21https://orcid.org/0000-0003-4383-2969(DELVE Collaboration)Department of Physics and Astronomy , Dartmouth College, Hanover, NH 03755, USA ; quinn.o.casey.gr@dartmouth.eduDepartment of Physics and Astronomy , Dartmouth College, Hanover, NH 03755, USA ; quinn.o.casey.gr@dartmouth.eduSteward Observatory, University of Arizona , 933 North Cherry Avenue, Tucson, AZ 85721-0065, USADepartment of Astronomy, University of Virginia , 530 McCormick Road, Charlottesville, VA 22904, USADepartment of Physics and Astronomy, University of Tampa , 401 West Kennedy Boulevard, Tampa, FL 33606, USADepartment of Physics and Astronomy , Dartmouth College, Hanover, NH 03755, USA ; quinn.o.casey.gr@dartmouth.eduDepartment of Astronomy, Yale University , New Haven, CT 06520, USADepartment of Astronomy and Astrophysics, University of Toronto , 50 St George Street, Toronto, ON M5S 3H4, Canada; Dunlap Institute for Astronomy and Astrophysics, University of Toronto , 50 St George Street, Toronto, ON M5S 3H4, CanadaInstitute for Computational Cosmology, Department of Physics, Durham University , South Road, Durham DH1 3LE, UKDepartment of Astronomy & Astrophysics, University of Chicago , 5640 S. Ellis Avenue, Chicago, IL 60637, USA; Kavli Institute for Cosmological Physics, University of Chicago , Chicago, IL 60637, USAKavli Institute for Cosmological Physics, University of Chicago , Chicago, IL 60637, USA; Universidade de São Paulo , IAG, Departamento de Astronomia, SP 05508-090, São Paulo, BrazilDepartment of Physics and Astronomy , Dartmouth College, Hanover, NH 03755, USA ; quinn.o.casey.gr@dartmouth.eduInternational Gemini Observatory/NSF NOIRLab , 670 N. A’ohoku Place, Hilo, HI 96720, USADepartment of Astronomy and Astrophysics, University of Toronto , 50 St George Street, Toronto, ON M5S 3H4, CanadaDepartment of Astronomy and Astrophysics, University of Toronto , 50 St George Street, Toronto, ON M5S 3H4, CanadaDepartment of Physics and Astronomy , Dartmouth College, Hanover, NH 03755, USA ; quinn.o.casey.gr@dartmouth.eduDepartment of Physics, University of Surrey , Guildford GU2 7XH, UKDepartment of Physics, University of Surrey , Guildford GU2 7XH, UKCerro Tololo Inter-American Observatory/NSF NOIRLab , Casilla 603, La Serena, ChileInstituto de Alta Investigación, Universidad de Tarapacá , Casilla 7D, Arica, ChileDepartment of Physics, University of Surrey , Guildford GU2 7XH, UKCentro Brasileiro de Pesquisas Físicas , Rua Dr. Xavier Sigaud 150, 22290-180 Rio de Janeiro, RJ, BrazilWe present deep Magellan+Megacam imaging of Centaurus I (Cen I) and Eridanus IV (Eri IV), two recently discovered Milky Way ultrafaint satellites. Our data reach ∼2–3 mag deeper than the discovery data from the DECam Local Volume Exploration Survey. We use these data to constrain their distances, structural properties (e.g., half-light radii, ellipticity, and position angle), and luminosities. We investigate whether these systems show signs of tidal disturbance and identify new potential member stars using Gaia EDR3. Our deep color–magnitude diagrams show that Cen I and Eri IV are consistent with an old ( τ ∼ 13.0 Gyr) and metal-poor ([Fe/H] ≤ −2.2) stellar population. We find Cen I to have a half-light radius of ${r}_{h}=2.\,^{\prime} 60\pm 0.\,^{\prime} 30\,$ (90.6 ± 11 pc), an ellipticity of ϵ = 0.36 ± 0.05, a distance of D = 119.8 ± 4.1 kpc ( m − M = 20.39 ± 0.08 mag), and an absolute magnitude of M _V = −5.39 ± 0.19. Similarly, Eri IV has ${r}_{h}=3.\,^{\prime} 24\pm 0.\,^{\prime} 48\,$ (65.9 ± 10 pc), ϵ = 0.26 ± 0.09, D = 69.9 ± 3.6 kpc ( m − M = 19.22 ± 0.11 mag), and M _V = −3.55 ± 0.24. These systems occupy a space on the size–luminosity plane consistent with other known Milky Way dwarf galaxies, which supports the findings from our previous spectroscopic follow-up. Cen I has a well-defined morphology that lacks any clear evidence of tidal disruption, whereas Eri IV hosts a significant extended feature with multiple possible interpretations.https://doi.org/10.3847/1538-4357/adc67eDwarf galaxiesGalaxy structureStellar populationsDirect imaging |
| spellingShingle | Quinn O. Casey Burçin Mutlu-Pakdil David J. Sand Andrew B. Pace Denija Crnojević Amandine Doliva-Dolinsky William Cerny Mairead E. Heiger Alex H. Riley Alexander P. Ji Guilherme Limberg Laurella Marin Clara E. Martínez-Vázquez Gustavo E. Medina Ting S. Li Sasha N. Campana Astha Chaturvedi Joanna D. Sakowska Alfredo Zenteno Julio A. Carballo-Bello Mahdieh Navabi Clecio R. Bom (DELVE Collaboration) Deep Photometric Observations of Ultrafaint Milky Way Satellites Centaurus I and Eridanus IV The Astrophysical Journal Dwarf galaxies Galaxy structure Stellar populations Direct imaging |
| title | Deep Photometric Observations of Ultrafaint Milky Way Satellites Centaurus I and Eridanus IV |
| title_full | Deep Photometric Observations of Ultrafaint Milky Way Satellites Centaurus I and Eridanus IV |
| title_fullStr | Deep Photometric Observations of Ultrafaint Milky Way Satellites Centaurus I and Eridanus IV |
| title_full_unstemmed | Deep Photometric Observations of Ultrafaint Milky Way Satellites Centaurus I and Eridanus IV |
| title_short | Deep Photometric Observations of Ultrafaint Milky Way Satellites Centaurus I and Eridanus IV |
| title_sort | deep photometric observations of ultrafaint milky way satellites centaurus i and eridanus iv |
| topic | Dwarf galaxies Galaxy structure Stellar populations Direct imaging |
| url | https://doi.org/10.3847/1538-4357/adc67e |
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