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The Hubble Space Telescope Survey of M31 Satellite Galaxies. I. RR Lyrae-based Distances and Refined 3D Geometric Structure

Savino, Alessandro and Weisz, Daniel R. and Skillman, Evan D. and Dolphin, Andrew E. and Kallivayalil, Nitya and Wetzel, Andrew and Anderson, Jay and Besla, Gurtina and Boylan-Kolchin, Michael and Bullock, James S. and Cole, Andrew A. and Collins, Michelle L. M. and Cooper, M. C. and Deason, Alis J. and Dotter, Aaron L. and Fardal, Mark and Ferguson, Annette M. N. and Fritz, Tobias K. and Geha, Marla C. and Gilbert, Karoline M. and Guhathakurta, Puragra and Ibata, Rodrigo and Irwin, Michael J. and Jeon, Myoungwon and Kirby, Evan and Lewis, Geraint F. and Mackey, Dougal and Majewski, Steven R. and Martin, Nicolas and McConnachie, Alan and Patel, Ekta and Rich, R. Michael and Simon, Joshua D. and Sohn, Sangmo Tony and Tollerud, Erik J. and van der Marel, Roeland P. (2022) The Hubble Space Telescope Survey of M31 Satellite Galaxies. I. RR Lyrae-based Distances and Refined 3D Geometric Structure. Astrophysical Journal, 938 (2). Art. No. 101. ISSN 0004-637X. doi:10.3847/1538-4357/ac91cb.

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We measure homogeneous distances to M31 and 38 associated stellar systems (−16.8 ≤ M_V ≤ −6.0), using time-series observations of RR Lyrae stars taken as part of the Hubble Space Telescope Treasury Survey of M31 Satellites. From >700 orbits of new/archival Advanced Camera for Surveys imaging, we identify >4700 RR Lyrae stars and determine their periods and mean magnitudes to a typical precision of 0.01 day and 0.04 mag. Based on period–Wesenheit–metallicity relationships consistent with the Gaia eDR3 distance scale, we uniformly measure heliocentric and M31-centric distances to a typical precision of ∼20 kpc (3%) and ∼10 kpc (8%), respectively. We revise the 3D structure of the M31 galactic ecosystem and: (i) confirm a highly anisotropic spatial distribution such that ∼80% of M31's satellites reside on the near side of M31; this feature is not easily explained by observational effects; (ii) affirm the thin (rms 7–23 kpc) planar “arc” of satellites that comprises roughly half (15) of the galaxies within 300 kpc from M31; (iii) reassess the physical proximity of notable associations such as the NGC 147/185 pair and M33/AND xxii; and (iv) illustrate challenges in tip-of-the-red-giant branch distances for galaxies with M_V > − 9.5, which can be biased by up to 35%. We emphasize the importance of RR Lyrae for accurate distances to faint galaxies that should be discovered by upcoming facilities (e.g., Rubin Observatory). We provide updated luminosities and sizes for our sample. Our distances will serve as the basis for future investigation of the star formation and orbital histories of the entire known M31 satellite system.

Item Type:Article
Related URLs:
URLURL TypeDescription
Savino, Alessandro0000-0002-1445-4877
Weisz, Daniel R.0000-0002-6442-6030
Skillman, Evan D.0000-0003-0605-8732
Dolphin, Andrew E.0000-0001-8416-4093
Kallivayalil, Nitya0000-0002-3204-1742
Wetzel, Andrew0000-0003-0603-8942
Anderson, Jay0000-0003-2861-3995
Besla, Gurtina0000-0003-0715-2173
Boylan-Kolchin, Michael0000-0002-9604-343X
Bullock, James S.0000-0003-4298-5082
Cole, Andrew A.0000-0003-0303-3855
Collins, Michelle L. M.0000-0002-1693-3265
Cooper, M. C.0000-0003-1371-6019
Deason, Alis J.0000-0001-6146-2645
Dotter, Aaron L.0000-0002-4442-5700
Fardal, Mark0000-0003-4207-3788
Ferguson, Annette M. N.0000-0001-7934-1278
Fritz, Tobias K.0000-0002-3122-300X
Geha, Marla C.0000-0002-7007-9725
Gilbert, Karoline M.0000-0003-0394-8377
Guhathakurta, Puragra0000-0001-8867-4234
Ibata, Rodrigo0000-0002-3292-9709
Irwin, Michael J.0000-0002-2191-9038
Jeon, Myoungwon0000-0001-6529-9777
Kirby, Evan0000-0001-6196-5162
Lewis, Geraint F.0000-0003-3081-9319
Mackey, Dougal0000-0002-6529-8093
Majewski, Steven R.0000-0003-2025-3147
Martin, Nicolas0000-0002-1349-202X
McConnachie, Alan0000-0003-4666-6564
Patel, Ekta0000-0002-9820-1219
Rich, R. Michael0000-0003-0427-8387
Simon, Joshua D.0000-0002-4733-4994
Sohn, Sangmo Tony0000-0001-8368-0221
Tollerud, Erik J.0000-0002-9599-310X
van der Marel, Roeland P.0000-0001-7827-7825
Additional Information:A.S. thanks Y. Zheng for useful discussions at various stages of this work. Support for this work was provided by NASA through grants GO-13768, GO-15746, GO-15902, AR-16159, and GO-16273 from the Space Telescope Science Institute, which is operated by AURA, Inc., under NASA contract NAS5-26555. M.C.C. acknowledges support though NSF grant AST-1815475. M.B.K. acknowledges support from NSF CAREER award AST-1752913, NSF grants AST-1910346 and AST-2108962, NASA grant NNX17AG29G, and HST-AR-15006, HST-AR-15809, HST-GO-15658, HST-GO-15901, HST-GO-15902, HST-AR-16159, and HST-GO-16226 from STScI. A.S. wishes to thank M. Marconi and R. Molinaro for providing the PWZ scaling relations used in this paper. This research has made use of NASA's Astrophysics Data System Bibliographic Services. All of the HST data used in this paper can be found in MAST:10.17909/jb41-ex86.
Group:Astronomy Department
Funding AgencyGrant Number
Issue or Number:2
Record Number:CaltechAUTHORS:20221031-575177800.33
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:117668
Deposited By: Research Services Depository
Deposited On:09 Nov 2022 20:17
Last Modified:11 Nov 2022 18:56

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