Hydra II: a faint and compact milky way dwarf galaxy found in the survey of the magellanic stellar history

Nicolas F. Martin; David L. Nidever; Gurtina Besla; Knut Olsen; Alistair R. Walker; A. Katherina Vivas; Robert A. Gruendl; Catherine C. Kaleida; Ricardo R. Muñoz; Robert D. Blum; Abhijit Saha; Blair C. Conn; Eric F. Bell; You Hua Chu; M-R.L. Cioni; Thomas J. L. De Boer; Carme Gallart; Shoko Jin; Andrea Kunder; Steven R. Majewski; David Martinez-Delgado; Antonela Monachesi; Matteo Monelli; Lara Monteagudo; Noelia E.D. Noël; Edward W. Olszewski; Guy S. Stringfellow; Roeland P. Van Der Marel; Dennis Zaritsky

doi:10.1088/2041-8205/804/1/L5

Hydra II: a faint and compact milky way dwarf galaxy found in the survey of the magellanic stellar history

Nicolas F. Martin, David L. Nidever, Gurtina Besla, Knut Olsen, Alistair R. Walker, A. Katherina Vivas, Robert A. Gruendl, Catherine C. Kaleida, Ricardo R. Muñoz, Robert D. Blum, Abhijit Saha, Blair C. Conn, Eric F. Bell, You Hua Chu, M-R.L. Cioni, Thomas J. L. De Boer, Carme Gallart, Shoko Jin, Andrea Kunder, Steven R. MajewskiDavid Martinez-Delgado, Antonela Monachesi, Matteo Monelli, Lara Monteagudo, Noelia E.D. Noël, Edward W. Olszewski, Guy S. Stringfellow, Roeland P. Van Der Marel, Dennis Zaritsky

Centre for Astrophysics Research (CAR)

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Abstract

We present the discovery of a new dwarf galaxy, Hydra II, found serendipitously within the data from the ongoing Survey of the Magellanic Stellar History conducted with the Dark Energy Camera on the Blanco 4 m Telescope. The new satellite is compact (r_h = 68 ± 11 pc) and faint (M_V = -4.8 ± 0.3), but well within the realm of dwarf galaxies. The stellar distribution of Hydra II in the color-magnitude diagram is well-described by a metal-poor ([Fe/H] = -2.2) and old (13 Gyr) isochrone and shows a distinct blue horizontal branch, some possible red clump stars, and faint stars that are suggestive of blue stragglers. At a heliocentric distance of 134 ± 10 kpc, Hydra II is located in a region of the Galactic halo that models have suggested may host material from the leading arm of the Magellanic Stream. A comparison with N-body simulations hints that the new dwarf galaxy could be or could have been a satellite of the Magellanic Clouds.

Original language	English
Article number	L5
Journal	Astrophysical Journal Letters
Volume	804
Issue number	1
Early online date	23 Apr 2015
DOIs	https://doi.org/10.1088/2041-8205/804/1/L5
Publication status	Published - 1 May 2015

Keywords

galaxies: individual (Hydra II)
Local Group
Magellanic Clouds

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Martin, N. F., Nidever, D. L., Besla, G., Olsen, K., Walker, A. R., Vivas, A. K., Gruendl, R. A., Kaleida, C. C., Muñoz, R. R., Blum, R. D., Saha, A., Conn, B. C., Bell, E. F., Chu, Y. H., Cioni, M.-RL., De Boer, T. J. L., Gallart, C., Jin, S., Kunder, A., ... Zaritsky, D. (2015). Hydra II: a faint and compact milky way dwarf galaxy found in the survey of the magellanic stellar history. Astrophysical Journal Letters, 804(1), Article L5. https://doi.org/10.1088/2041-8205/804/1/L5

@article{0a45ea27a57f4abf860ff4054bafb4df,

title = "Hydra II: a faint and compact milky way dwarf galaxy found in the survey of the magellanic stellar history",

abstract = "We present the discovery of a new dwarf galaxy, Hydra II, found serendipitously within the data from the ongoing Survey of the Magellanic Stellar History conducted with the Dark Energy Camera on the Blanco 4 m Telescope. The new satellite is compact (r_h = 68 ± 11 pc) and faint (M_V = -4.8 ± 0.3), but well within the realm of dwarf galaxies. The stellar distribution of Hydra II in the color-magnitude diagram is well-described by a metal-poor ([Fe/H] = -2.2) and old (13 Gyr) isochrone and shows a distinct blue horizontal branch, some possible red clump stars, and faint stars that are suggestive of blue stragglers. At a heliocentric distance of 134 ± 10 kpc, Hydra II is located in a region of the Galactic halo that models have suggested may host material from the leading arm of the Magellanic Stream. A comparison with N-body simulations hints that the new dwarf galaxy could be or could have been a satellite of the Magellanic Clouds.",

keywords = "galaxies: individual (Hydra II), Local Group, Magellanic Clouds",

author = "Martin, {Nicolas F.} and Nidever, {David L.} and Gurtina Besla and Knut Olsen and Walker, {Alistair R.} and Vivas, {A. Katherina} and Gruendl, {Robert A.} and Kaleida, {Catherine C.} and Mu{\~n}oz, {Ricardo R.} and Blum, {Robert D.} and Abhijit Saha and Conn, {Blair C.} and Bell, {Eric F.} and Chu, {You Hua} and M-R.L. Cioni and {De Boer}, {Thomas J. L.} and Carme Gallart and Shoko Jin and Andrea Kunder and Majewski, {Steven R.} and David Martinez-Delgado and Antonela Monachesi and Matteo Monelli and Lara Monteagudo and No{\"e}l, {Noelia E.D.} and Olszewski, {Edward W.} and Stringfellow, {Guy S.} and {Van Der Marel}, {Roeland P.} and Dennis Zaritsky",

note = "Date of Acceptance: 31/03/2015",

year = "2015",

month = may,

day = "1",

doi = "10.1088/2041-8205/804/1/L5",

language = "English",

volume = "804",

journal = "Astrophysical Journal Letters",

issn = "2041-8205",

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Martin, NF, Nidever, DL, Besla, G, Olsen, K, Walker, AR, Vivas, AK, Gruendl, RA, Kaleida, CC, Muñoz, RR, Blum, RD, Saha, A, Conn, BC, Bell, EF, Chu, YH, Cioni, M-RL, De Boer, TJL, Gallart, C, Jin, S, Kunder, A, Majewski, SR, Martinez-Delgado, D, Monachesi, A, Monelli, M, Monteagudo, L, Noël, NED, Olszewski, EW, Stringfellow, GS, Van Der Marel, RP & Zaritsky, D 2015, 'Hydra II: a faint and compact milky way dwarf galaxy found in the survey of the magellanic stellar history', Astrophysical Journal Letters, vol. 804, no. 1, L5. https://doi.org/10.1088/2041-8205/804/1/L5

TY - JOUR

T1 - Hydra II: a faint and compact milky way dwarf galaxy found in the survey of the magellanic stellar history

AU - Martin, Nicolas F.

AU - Nidever, David L.

AU - Besla, Gurtina

AU - Olsen, Knut

AU - Walker, Alistair R.

AU - Vivas, A. Katherina

AU - Gruendl, Robert A.

AU - Kaleida, Catherine C.

AU - Muñoz, Ricardo R.

AU - Blum, Robert D.

AU - Saha, Abhijit

AU - Conn, Blair C.

AU - Bell, Eric F.

AU - Chu, You Hua

AU - Cioni, M-R.L.

AU - De Boer, Thomas J. L.

AU - Gallart, Carme

AU - Jin, Shoko

AU - Kunder, Andrea

AU - Majewski, Steven R.

AU - Martinez-Delgado, David

AU - Monachesi, Antonela

AU - Monelli, Matteo

AU - Monteagudo, Lara

AU - Noël, Noelia E.D.

AU - Olszewski, Edward W.

AU - Stringfellow, Guy S.

AU - Van Der Marel, Roeland P.

AU - Zaritsky, Dennis

N1 - Date of Acceptance: 31/03/2015

PY - 2015/5/1

Y1 - 2015/5/1

N2 - We present the discovery of a new dwarf galaxy, Hydra II, found serendipitously within the data from the ongoing Survey of the Magellanic Stellar History conducted with the Dark Energy Camera on the Blanco 4 m Telescope. The new satellite is compact (r_h = 68 ± 11 pc) and faint (M_V = -4.8 ± 0.3), but well within the realm of dwarf galaxies. The stellar distribution of Hydra II in the color-magnitude diagram is well-described by a metal-poor ([Fe/H] = -2.2) and old (13 Gyr) isochrone and shows a distinct blue horizontal branch, some possible red clump stars, and faint stars that are suggestive of blue stragglers. At a heliocentric distance of 134 ± 10 kpc, Hydra II is located in a region of the Galactic halo that models have suggested may host material from the leading arm of the Magellanic Stream. A comparison with N-body simulations hints that the new dwarf galaxy could be or could have been a satellite of the Magellanic Clouds.

AB - We present the discovery of a new dwarf galaxy, Hydra II, found serendipitously within the data from the ongoing Survey of the Magellanic Stellar History conducted with the Dark Energy Camera on the Blanco 4 m Telescope. The new satellite is compact (r_h = 68 ± 11 pc) and faint (M_V = -4.8 ± 0.3), but well within the realm of dwarf galaxies. The stellar distribution of Hydra II in the color-magnitude diagram is well-described by a metal-poor ([Fe/H] = -2.2) and old (13 Gyr) isochrone and shows a distinct blue horizontal branch, some possible red clump stars, and faint stars that are suggestive of blue stragglers. At a heliocentric distance of 134 ± 10 kpc, Hydra II is located in a region of the Galactic halo that models have suggested may host material from the leading arm of the Magellanic Stream. A comparison with N-body simulations hints that the new dwarf galaxy could be or could have been a satellite of the Magellanic Clouds.

KW - galaxies: individual (Hydra II)

KW - Local Group

KW - Magellanic Clouds

U2 - 10.1088/2041-8205/804/1/L5

DO - 10.1088/2041-8205/804/1/L5

M3 - Article

AN - SCOPUS:84928820684

SN - 2041-8205

VL - 804

JO - Astrophysical Journal Letters

JF - Astrophysical Journal Letters

IS - 1

M1 - L5

ER -

Hydra II: a faint and compact milky way dwarf galaxy found in the survey of the magellanic stellar history

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Keywords

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