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, Maria Rosa L Cioni, Thomas J L De Boer, Carme Gallart, Shoko Jin, Andrea Kunder, Steven R. Majewski & 9 others 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 F Zaritsky

Research output: Contribution to journalArticle

80 Citations (Scopus)

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<inf>h</inf> = 68 ± 11 pc) and faint (M<inf>V</inf> = -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 languageEnglish (US)
Article numberL5
JournalAstrophysical Journal Letters
Volume804
Issue number1
DOIs
StatePublished - May 1 2015

Fingerprint

Milky Way Galaxy
Hydra
dwarf galaxies
histories
history
stars
galactic halos
color-magnitude diagram
diagram
Magellanic clouds
clumps
dark energy
metal
cameras
telescopes
simulation
energy
metals
distribution
comparison

Keywords

  • galaxies: individual (Hydra II)
  • Local Group
  • Magellanic Clouds

ASJC Scopus subject areas

  • Space and Planetary Science
  • Astronomy and Astrophysics

Cite this

HYDRA II : A FAINT AND COMPACT MILKY WAY DWARF GALAXY FOUND IN THE SURVEY OF THE MAGELLANIC STELLAR HISTORY. / Martin, Nicolas F.; Nidever, David L.; Besla, Gurtina; Olsen, Knut; Walker, Alistair R.; Vivas, A. Katherina; Gruendl, Robert A.; Kaleida, Catherine C.; Muñoz, Ricardo R.; Blum, Robert D.; Saha, Abhijit; Conn, Blair C.; Bell, Eric F.; Chu, You Hua; Cioni, Maria Rosa L; De Boer, Thomas J L; Gallart, Carme; Jin, Shoko; Kunder, Andrea; Majewski, Steven R.; Martinez-Delgado, David; Monachesi, Antonela; Monelli, Matteo; Monteagudo, Lara; Noël, Noelia E D; Olszewski, Edward W; Stringfellow, Guy S.; Van Der Marel, Roeland P.; Zaritsky, Dennis F.

In: Astrophysical Journal Letters, Vol. 804, No. 1, L5, 01.05.2015.

Research output: Contribution to journalArticle

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, MRL, 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, DF 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
Martin, Nicolas F. ; Nidever, David L. ; Besla, Gurtina ; Olsen, Knut ; Walker, Alistair R. ; Vivas, A. Katherina ; Gruendl, Robert A. ; Kaleida, Catherine C. ; Muñoz, Ricardo R. ; Blum, Robert D. ; Saha, Abhijit ; Conn, Blair C. ; Bell, Eric F. ; Chu, You Hua ; Cioni, Maria Rosa L ; De Boer, Thomas J L ; Gallart, Carme ; Jin, Shoko ; Kunder, Andrea ; Majewski, Steven R. ; Martinez-Delgado, David ; Monachesi, Antonela ; Monelli, Matteo ; Monteagudo, Lara ; Noël, Noelia E D ; Olszewski, Edward W ; Stringfellow, Guy S. ; Van Der Marel, Roeland P. ; Zaritsky, Dennis F. / HYDRA II : A FAINT AND COMPACT MILKY WAY DWARF GALAXY FOUND IN THE SURVEY OF THE MAGELLANIC STELLAR HISTORY. In: Astrophysical Journal Letters. 2015 ; Vol. 804, No. 1.
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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 (rh = 68 ± 11 pc) and faint (MV = -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.",
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T2 - 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, Maria Rosa 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 F

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 (rh = 68 ± 11 pc) and faint (MV = -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 (rh = 68 ± 11 pc) and faint (MV = -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

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JO - Astrophysical Journal Letters

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