Ghosts I: a new faint very isolated dwarf galaxy at D = 12 ± 2 Mpc

Antonela Monachesi; Eric F. Bell; David J. Radburn-Smith; Roelof S. De Jong; Jeremy Bailin; Julianne J. Dalcanton; Benne W. Holwerda; H. Alyson Ford; David Streich; Marija Vlajić; Daniel B. Zucker

doi:10.1088/0004-637X/780/2/179

Ghosts I: a new faint very isolated dwarf galaxy at D = 12 ± 2 Mpc

Antonela Monachesi, Eric F. Bell, David J. Radburn-Smith, Roelof S. De Jong, Jeremy Bailin, Julianne J. Dalcanton, Benne W. Holwerda, H. Alyson Ford, David Streich, Marija Vlajić, Daniel B. Zucker

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Abstract

We report the discovery of a new faint dwarf galaxy, GHOSTS I, using HST/ACS data from one of our GHOSTS (Galaxy Halos, Outer disks, Substructure, Thick disk, and Star clusters) fields. Its detected individual stars populate an approximately 1 mag range of its luminosity function (LF). Using synthetic color-magnitude diagrams (CMDs) to compare with the galaxy's CMD, we find that the colors and magnitudes of GHOSTS I's individual stars are most consistent with being young helium-burning and asymptotic giant branch stars at a distance of 12 ± 2 Mpc. Morphologically, GHOSTS I appears to be actively forming stars, so we tentatively classify it as a dwarf irregular (dIrr) galaxy, although future Hubble Space Telescope (HST) observations deep enough to resolve a larger magnitude range in its LF are required to make a more secure classification. GHOSTS I's absolute magnitude is , making it one of the least luminous dIrr galaxies known, and its metallicity is lower than [Fe/H] = -1.5 dex. The half-light radius of GHOSTS I is 226 ± 38 pc and its ellipticity is 0.47 ± 0.07, similar to Milky Way and M31 dwarf satellites at comparable luminosity. There are no luminous massive galaxies or galaxy clusters within 4 Mpc from GHOSTS I that could be considered as its host, making it a very isolated dwarf galaxy in the local universe.

Original language	English
Article number	179
Pages (from-to)	1-8
Number of pages	8
Journal	Astrophysical Journal
Volume	780
Issue number	2
DOIs	https://doi.org/10.1088/0004-637X/780/2/179
Publication status	Published - 10 Jan 2014

Bibliographical note

Copyright 2014 The American Astronomical Society. First published in the Astrophysical journal, 780(2), 179, 2014, published by IOP Publishing. The original publication is available at http://www.doi.org/10.1088/0004-637X/780/2/179. Version archived for private and non-commercial use with the permission of the author/s and according to publisher conditions. For further rights please contact the publisher.

Keywords

galaxies: dwarf
galaxies: individual (GHOSTS I)

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10.1088/0004-637X/780/2/179

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Cite this

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title = "Ghosts I: a new faint very isolated dwarf galaxy at D = 12 ± 2 Mpc",

abstract = "We report the discovery of a new faint dwarf galaxy, GHOSTS I, using HST/ACS data from one of our GHOSTS (Galaxy Halos, Outer disks, Substructure, Thick disk, and Star clusters) fields. Its detected individual stars populate an approximately 1 mag range of its luminosity function (LF). Using synthetic color-magnitude diagrams (CMDs) to compare with the galaxy's CMD, we find that the colors and magnitudes of GHOSTS I's individual stars are most consistent with being young helium-burning and asymptotic giant branch stars at a distance of 12 ± 2 Mpc. Morphologically, GHOSTS I appears to be actively forming stars, so we tentatively classify it as a dwarf irregular (dIrr) galaxy, although future Hubble Space Telescope (HST) observations deep enough to resolve a larger magnitude range in its LF are required to make a more secure classification. GHOSTS I's absolute magnitude is , making it one of the least luminous dIrr galaxies known, and its metallicity is lower than [Fe/H] = -1.5 dex. The half-light radius of GHOSTS I is 226 ± 38 pc and its ellipticity is 0.47 ± 0.07, similar to Milky Way and M31 dwarf satellites at comparable luminosity. There are no luminous massive galaxies or galaxy clusters within 4 Mpc from GHOSTS I that could be considered as its host, making it a very isolated dwarf galaxy in the local universe.",

keywords = "galaxies: dwarf, galaxies: individual (GHOSTS I)",

author = "Antonela Monachesi and Bell, {Eric F.} and Radburn-Smith, {David J.} and {De Jong}, {Roelof S.} and Jeremy Bailin and Dalcanton, {Julianne J.} and Holwerda, {Benne W.} and {Alyson Ford}, H. and David Streich and Marija Vlaji{\'c} and Zucker, {Daniel B.}",

note = "Copyright 2014 The American Astronomical Society. First published in the Astrophysical journal, 780(2), 179, 2014, published by IOP Publishing. The original publication is available at http://www.doi.org/10.1088/0004-637X/780/2/179. Version archived for private and non-commercial use with the permission of the author/s and according to publisher conditions. For further rights please contact the publisher.",

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doi = "10.1088/0004-637X/780/2/179",

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T2 - a new faint very isolated dwarf galaxy at D = 12 ± 2 Mpc

AU - Monachesi, Antonela

AU - Bell, Eric F.

AU - Radburn-Smith, David J.

AU - De Jong, Roelof S.

AU - Bailin, Jeremy

AU - Dalcanton, Julianne J.

AU - Holwerda, Benne W.

AU - Alyson Ford, H.

AU - Streich, David

AU - Vlajić, Marija

AU - Zucker, Daniel B.

N1 - Copyright 2014 The American Astronomical Society. First published in the Astrophysical journal, 780(2), 179, 2014, published by IOP Publishing. The original publication is available at http://www.doi.org/10.1088/0004-637X/780/2/179. Version archived for private and non-commercial use with the permission of the author/s and according to publisher conditions. For further rights please contact the publisher.

PY - 2014/1/10

Y1 - 2014/1/10

N2 - We report the discovery of a new faint dwarf galaxy, GHOSTS I, using HST/ACS data from one of our GHOSTS (Galaxy Halos, Outer disks, Substructure, Thick disk, and Star clusters) fields. Its detected individual stars populate an approximately 1 mag range of its luminosity function (LF). Using synthetic color-magnitude diagrams (CMDs) to compare with the galaxy's CMD, we find that the colors and magnitudes of GHOSTS I's individual stars are most consistent with being young helium-burning and asymptotic giant branch stars at a distance of 12 ± 2 Mpc. Morphologically, GHOSTS I appears to be actively forming stars, so we tentatively classify it as a dwarf irregular (dIrr) galaxy, although future Hubble Space Telescope (HST) observations deep enough to resolve a larger magnitude range in its LF are required to make a more secure classification. GHOSTS I's absolute magnitude is , making it one of the least luminous dIrr galaxies known, and its metallicity is lower than [Fe/H] = -1.5 dex. The half-light radius of GHOSTS I is 226 ± 38 pc and its ellipticity is 0.47 ± 0.07, similar to Milky Way and M31 dwarf satellites at comparable luminosity. There are no luminous massive galaxies or galaxy clusters within 4 Mpc from GHOSTS I that could be considered as its host, making it a very isolated dwarf galaxy in the local universe.

AB - We report the discovery of a new faint dwarf galaxy, GHOSTS I, using HST/ACS data from one of our GHOSTS (Galaxy Halos, Outer disks, Substructure, Thick disk, and Star clusters) fields. Its detected individual stars populate an approximately 1 mag range of its luminosity function (LF). Using synthetic color-magnitude diagrams (CMDs) to compare with the galaxy's CMD, we find that the colors and magnitudes of GHOSTS I's individual stars are most consistent with being young helium-burning and asymptotic giant branch stars at a distance of 12 ± 2 Mpc. Morphologically, GHOSTS I appears to be actively forming stars, so we tentatively classify it as a dwarf irregular (dIrr) galaxy, although future Hubble Space Telescope (HST) observations deep enough to resolve a larger magnitude range in its LF are required to make a more secure classification. GHOSTS I's absolute magnitude is , making it one of the least luminous dIrr galaxies known, and its metallicity is lower than [Fe/H] = -1.5 dex. The half-light radius of GHOSTS I is 226 ± 38 pc and its ellipticity is 0.47 ± 0.07, similar to Milky Way and M31 dwarf satellites at comparable luminosity. There are no luminous massive galaxies or galaxy clusters within 4 Mpc from GHOSTS I that could be considered as its host, making it a very isolated dwarf galaxy in the local universe.

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KW - galaxies: individual (GHOSTS I)

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SN - 0004-637X

VL - 780

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JO - Astrophysical Journal

JF - Astrophysical Journal

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ER -

Ghosts I: a new faint very isolated dwarf galaxy at D = 12 ± 2 Mpc

Abstract

Bibliographical note

Keywords

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