Andromeda XXXV: The Faintest Dwarf Satellite of the Andromeda Galaxy

We present the discovery of Andromeda XXXV, the faintest Andromeda satellite galaxy discovered to date, identified as an overdensity of stars in the Pan-Andromeda Archaeological Survey and confirmed via Hubble Space Telescope imaging. Located at a heliocentric distance of $92{7}_{-63}^{+76}$ kpc and...

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Main Authors: Jose Marco Arias, Eric F. Bell, Katya Gozman, In Sung Jang, Saxon Stockton, Oleg Y. Gnedin, Richard D’Souza, Antonela Monachesi, Jeremy Bailin, David Nidever, Roelof S. de Jong
Format: Article
Language:English
Published: IOP Publishing 2025-01-01
Series:The Astrophysical Journal Letters
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Online Access:https://doi.org/10.3847/2041-8213/adb433
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author Jose Marco Arias
Eric F. Bell
Katya Gozman
In Sung Jang
Saxon Stockton
Oleg Y. Gnedin
Richard D’Souza
Antonela Monachesi
Jeremy Bailin
David Nidever
Roelof S. de Jong
author_facet Jose Marco Arias
Eric F. Bell
Katya Gozman
In Sung Jang
Saxon Stockton
Oleg Y. Gnedin
Richard D’Souza
Antonela Monachesi
Jeremy Bailin
David Nidever
Roelof S. de Jong
author_sort Jose Marco Arias
collection DOAJ
description We present the discovery of Andromeda XXXV, the faintest Andromeda satellite galaxy discovered to date, identified as an overdensity of stars in the Pan-Andromeda Archaeological Survey and confirmed via Hubble Space Telescope imaging. Located at a heliocentric distance of $92{7}_{-63}^{+76}$ kpc and $15{8}_{-45}^{+57}$ kpc from Andromeda, Andromeda XXXV is an extended ( ${r}_{h}=5{3\,}_{-11}^{+13}$ pc), elliptical ( ϵ  = 0.4 ± 0.2), metal-poor ([Fe/H] ∼ −1.9) system, and the least luminous ( M _V  = −5.2 ± 0.3) of Andromeda’s dwarf satellites discovered so far. Andromeda XXXV’s properties are consistent with the known population of dwarf galaxies around the Local Group, bearing close structural resemblance to the Canes Venatici II and Hydra II Milky Way (MW) dwarf satellite galaxies. Its stellar population, characterized by a red horizontal branch or a red clump feature, mirrors that of other Andromeda satellite galaxies in showing evidence for a spread in age and metallicity, with no signs of younger stellar generations. This age–metallicity spread is not observed in MW satellites of comparable stellar mass, and highlights the persistent differences between the satellite systems of Andromeda and the MW, extending even into the ultrafaint regime.
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spelling doaj-art-9d77bbc0ccc342d3badd2a24f81f5a8b2025-08-20T02:04:37ZengIOP PublishingThe Astrophysical Journal Letters2041-82052025-01-019821L310.3847/2041-8213/adb433Andromeda XXXV: The Faintest Dwarf Satellite of the Andromeda GalaxyJose Marco Arias0https://orcid.org/0009-0002-9085-5928Eric F. Bell1https://orcid.org/0000-0002-5564-9873Katya Gozman2https://orcid.org/0000-0003-2294-4187In Sung Jang3https://orcid.org/0000-0002-2502-0070Saxon Stockton4https://orcid.org/0000-0003-1677-0213Oleg Y. Gnedin5https://orcid.org/0000-0001-9852-9954Richard D’Souza6https://orcid.org/0000-0001-9269-8167Antonela Monachesi7https://orcid.org/0000-0003-2325-9616Jeremy Bailin8https://orcid.org/0000-0001-6380-010XDavid Nidever9https://orcid.org/0000-0002-1793-3689Roelof S. de Jong10https://orcid.org/0000-0001-6982-4081Department of Astronomy, University of Michigan , 1085 S. University Ave., Ann Arbor, MI 48109-1107, USA ; joarias@umich.eduDepartment of Astronomy, University of Michigan , 1085 S. University Ave., Ann Arbor, MI 48109-1107, USA ; joarias@umich.eduDepartment of Astronomy, University of Michigan , 1085 S. University Ave., Ann Arbor, MI 48109-1107, USA ; joarias@umich.eduDepartment of Astronomy and Astrophysics, University of Chicago , Chicago, IL 60637, USADepartment of Physics, Utah Valley University , 800 W. University Pkwy., Orem, UT 84058, USADepartment of Astronomy, University of Michigan , 1085 S. University Ave., Ann Arbor, MI 48109-1107, USA ; joarias@umich.eduVatican Observatory , Specola Vaticana, V-00120, Vatican City StateDepartamento de Astronomía, Universidad de La Serena , Avda. Rául Bitrán 1305, La Serena, ChileDepartment of Physics and Astronomy, University of Alabama , Box 870324, Tuscaloosa, AL 35487-0324, USADepartment of Physics, Montana State University , P.O. Box 173840, Bozeman, MT 59717-3840, USALeibniz-Institut für Astrophysik Potsdam (AIP) , An der Sternwarte 16, 14482 Potsdam, GermanyWe present the discovery of Andromeda XXXV, the faintest Andromeda satellite galaxy discovered to date, identified as an overdensity of stars in the Pan-Andromeda Archaeological Survey and confirmed via Hubble Space Telescope imaging. Located at a heliocentric distance of $92{7}_{-63}^{+76}$ kpc and $15{8}_{-45}^{+57}$ kpc from Andromeda, Andromeda XXXV is an extended ( ${r}_{h}=5{3\,}_{-11}^{+13}$ pc), elliptical ( ϵ  = 0.4 ± 0.2), metal-poor ([Fe/H] ∼ −1.9) system, and the least luminous ( M _V  = −5.2 ± 0.3) of Andromeda’s dwarf satellites discovered so far. Andromeda XXXV’s properties are consistent with the known population of dwarf galaxies around the Local Group, bearing close structural resemblance to the Canes Venatici II and Hydra II Milky Way (MW) dwarf satellite galaxies. Its stellar population, characterized by a red horizontal branch or a red clump feature, mirrors that of other Andromeda satellite galaxies in showing evidence for a spread in age and metallicity, with no signs of younger stellar generations. This age–metallicity spread is not observed in MW satellites of comparable stellar mass, and highlights the persistent differences between the satellite systems of Andromeda and the MW, extending even into the ultrafaint regime.https://doi.org/10.3847/2041-8213/adb433Dwarf galaxiesAndromeda Galaxy
spellingShingle Jose Marco Arias
Eric F. Bell
Katya Gozman
In Sung Jang
Saxon Stockton
Oleg Y. Gnedin
Richard D’Souza
Antonela Monachesi
Jeremy Bailin
David Nidever
Roelof S. de Jong
Andromeda XXXV: The Faintest Dwarf Satellite of the Andromeda Galaxy
The Astrophysical Journal Letters
Dwarf galaxies
Andromeda Galaxy
title Andromeda XXXV: The Faintest Dwarf Satellite of the Andromeda Galaxy
title_full Andromeda XXXV: The Faintest Dwarf Satellite of the Andromeda Galaxy
title_fullStr Andromeda XXXV: The Faintest Dwarf Satellite of the Andromeda Galaxy
title_full_unstemmed Andromeda XXXV: The Faintest Dwarf Satellite of the Andromeda Galaxy
title_short Andromeda XXXV: The Faintest Dwarf Satellite of the Andromeda Galaxy
title_sort andromeda xxxv the faintest dwarf satellite of the andromeda galaxy
topic Dwarf galaxies
Andromeda Galaxy
url https://doi.org/10.3847/2041-8213/adb433
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