DDO 68-C: HST Confirms Yet Another Companion of the Isolated Dwarf Galaxy DDO 68

We present the results of deep Hubble Space Telescope photometry of the dwarf galaxy DDO 68-C, proposed as possibly associated with the isolated peculiar dwarf DDO 68. The new data resolve for the first time the stars of DDO 68-C down to well below the tip of the red giant branch (RGB), revealing a...

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Main Authors: Matteo Correnti, Francesca Annibali, Michele Bellazzini, Mariarosa Marinelli, Alessandra Aloisi, Michele Cignoni, Monica Tosi, Raffaele Pascale, John M. Cannon, Lila Schisgal, Leslie K. Hunt, Elena Sacchi, Sangmo Tony Sohn
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Language:English
Published: IOP Publishing 2025-01-01
Series:The Astrophysical Journal
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Online Access:https://doi.org/10.3847/1538-4357/adb7e6
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author Matteo Correnti
Francesca Annibali
Michele Bellazzini
Mariarosa Marinelli
Alessandra Aloisi
Michele Cignoni
Monica Tosi
Raffaele Pascale
John M. Cannon
Lila Schisgal
Leslie K. Hunt
Elena Sacchi
Sangmo Tony Sohn
author_facet Matteo Correnti
Francesca Annibali
Michele Bellazzini
Mariarosa Marinelli
Alessandra Aloisi
Michele Cignoni
Monica Tosi
Raffaele Pascale
John M. Cannon
Lila Schisgal
Leslie K. Hunt
Elena Sacchi
Sangmo Tony Sohn
author_sort Matteo Correnti
collection DOAJ
description We present the results of deep Hubble Space Telescope photometry of the dwarf galaxy DDO 68-C, proposed as possibly associated with the isolated peculiar dwarf DDO 68. The new data resolve for the first time the stars of DDO 68-C down to well below the tip of the red giant branch (RGB), revealing a low-mass ( M _⋆ ≃ 1.5 × 10 ^7 M _⊙ ) star-forming galaxy with a backbone of old stars. By means of a fully homogeneous analysis and using the RGB tip as a standard candle, we find that DDO 68 and DDO 68-C lie at the same distance from us, within the uncertainties ( D = 12.6 ± 0.3 Mpc and D = 12.7 ± 0.4 Mpc, respectively), thus confirming that the two dwarfs are physically associated. While paired dwarf galaxies with a mutual projected distance similar to DDO 68 and DDO 68-C are not exceptional in the Lynx-Cancer void where they live, DDO 68 remains a unicum as, in addition to the newly confirmed companion, it records the evidence of at least two other satellites.
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spelling doaj-art-cf5c9ddb0a034c74bf5d0e2fa4c1f7522025-08-20T02:52:49ZengIOP PublishingThe Astrophysical Journal1538-43572025-01-0198213110.3847/1538-4357/adb7e6DDO 68-C: HST Confirms Yet Another Companion of the Isolated Dwarf Galaxy DDO 68Matteo Correnti0https://orcid.org/0000-0001-6464-3257Francesca Annibali1https://orcid.org/0000-0003-3758-4516Michele Bellazzini2https://orcid.org/0000-0001-8200-810XMariarosa Marinelli3https://orcid.org/0000-0002-4775-7292Alessandra Aloisi4https://orcid.org/0000-0003-4137-882XMichele Cignoni5https://orcid.org/0000-0001-6291-6813Monica Tosi6https://orcid.org/0000-0002-0986-4759Raffaele Pascale7https://orcid.org/0000-0002-6389-6268John M. Cannon8https://orcid.org/0000-0002-1821-7019Lila Schisgal9https://orcid.org/0009-0007-3163-3678Leslie K. Hunt10https://orcid.org/0000-0001-9162-2371Elena Sacchi11https://orcid.org/0000-0001-5618-0109Sangmo Tony Sohn12https://orcid.org/0000-0001-8368-0221INAF Osservatorio Astronomico di Roma , Via Frascati 33, 00078, Monteporzio Catone, Rome, Italy ; matteo.correnti@inaf.it; ASI-Space Science Data Center , Via del Politecnico, I-00133, Rome, ItalyINAF—Osservatorio di Astrofisica e Scienza dello Spazio di Bologna , via Piero Gobetti 93/3, 40129 Bologna, ItalyINAF—Osservatorio di Astrofisica e Scienza dello Spazio di Bologna , via Piero Gobetti 93/3, 40129 Bologna, ItalySpace Telescope Science Institute , 3700 San Martin Drive, Baltimore, MD 21218, USASpace Telescope Science Institute , 3700 San Martin Drive, Baltimore, MD 21218, USA; Astrophysics Division , Science Mission Directorate, NASA Headquarters, 300 E Street SW, Washington, DC 20546, USAINAF—Osservatorio di Astrofisica e Scienza dello Spazio di Bologna , via Piero Gobetti 93/3, 40129 Bologna, Italy; Dipartimento di Fisica, Università di Pisa , Largo Bruno Pontecorvo 3, 56127, Pisa, Italy; INFN , Largo B. Pontecorvo 3, 56127, Pisa, ItalyINAF—Osservatorio di Astrofisica e Scienza dello Spazio di Bologna , via Piero Gobetti 93/3, 40129 Bologna, ItalyINAF—Osservatorio di Astrofisica e Scienza dello Spazio di Bologna , via Piero Gobetti 93/3, 40129 Bologna, ItalyMacalester College , 1600 Grand Avenue, Saint Paul, MN 55105, USAMacalester College , 1600 Grand Avenue, Saint Paul, MN 55105, USAINAF-Osservatorio Astrofisico di Arcetri , Largo E. Fermi 5, 50125, Firenze, ItalyLeibniz-Institut für Astrophysik Potsdam (AIP) , An der Sternwarte 16, 14482 Potsdam, GermanySpace Telescope Science Institute , 3700 San Martin Drive, Baltimore, MD 21218, USA; Department of Astronomy & Space Science, Kyung Hee University , 1732 Deogyeong-daero, Yongin-si, Gyeonggi-do 17104, Republic of KoreaWe present the results of deep Hubble Space Telescope photometry of the dwarf galaxy DDO 68-C, proposed as possibly associated with the isolated peculiar dwarf DDO 68. The new data resolve for the first time the stars of DDO 68-C down to well below the tip of the red giant branch (RGB), revealing a low-mass ( M _⋆ ≃ 1.5 × 10 ^7 M _⊙ ) star-forming galaxy with a backbone of old stars. By means of a fully homogeneous analysis and using the RGB tip as a standard candle, we find that DDO 68 and DDO 68-C lie at the same distance from us, within the uncertainties ( D = 12.6 ± 0.3 Mpc and D = 12.7 ± 0.4 Mpc, respectively), thus confirming that the two dwarfs are physically associated. While paired dwarf galaxies with a mutual projected distance similar to DDO 68 and DDO 68-C are not exceptional in the Lynx-Cancer void where they live, DDO 68 remains a unicum as, in addition to the newly confirmed companion, it records the evidence of at least two other satellites.https://doi.org/10.3847/1538-4357/adb7e6Dwarf galaxiesGalaxy interactions
spellingShingle Matteo Correnti
Francesca Annibali
Michele Bellazzini
Mariarosa Marinelli
Alessandra Aloisi
Michele Cignoni
Monica Tosi
Raffaele Pascale
John M. Cannon
Lila Schisgal
Leslie K. Hunt
Elena Sacchi
Sangmo Tony Sohn
DDO 68-C: HST Confirms Yet Another Companion of the Isolated Dwarf Galaxy DDO 68
The Astrophysical Journal
Dwarf galaxies
Galaxy interactions
title DDO 68-C: HST Confirms Yet Another Companion of the Isolated Dwarf Galaxy DDO 68
title_full DDO 68-C: HST Confirms Yet Another Companion of the Isolated Dwarf Galaxy DDO 68
title_fullStr DDO 68-C: HST Confirms Yet Another Companion of the Isolated Dwarf Galaxy DDO 68
title_full_unstemmed DDO 68-C: HST Confirms Yet Another Companion of the Isolated Dwarf Galaxy DDO 68
title_short DDO 68-C: HST Confirms Yet Another Companion of the Isolated Dwarf Galaxy DDO 68
title_sort ddo 68 c hst confirms yet another companion of the isolated dwarf galaxy ddo 68
topic Dwarf galaxies
Galaxy interactions
url https://doi.org/10.3847/1538-4357/adb7e6
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