KINEMATICS AND CHEMISTRY OF RECENTLY DISCOVERED RETICULUM 2 AND HOROLOGIUM 1 DWARF GALAXIES

被引：120

作者：

Koposov, Sergey E. ^{[1
]}

Casey, Andrew R. ^{[1
]}

Belokurov, Vasily ^{[1
]}

Lewis, James R. ^{[1
]}

Gilmore, Gerard ^{[1
]}

Worley, Clare ^{[1
]}

Hourihane, Anna ^{[1
]}

Randich, S. ^{[2
]}

Bensby, T. ^{[3
]}

Bragaglia, A. ^{[4
]}

Bergemann, M. ^{[5
]}

Carraro, G. ^{[6
]}

Costado, M. T. ^{[7
]}

Flaccomio, E. ^{[8
]}

Francois, P. ^{[9
]}

Heiter, U. ^{[10
]}

Hill, V. ^{[11
]}

Jofre, P. ^{[1
]}

Lando, C. ^{[12
]}

Lanzafame, A. C. ^{[13
]}

de Laverny, P. ^{[11
]}

Monaco, L. ^{[14
]}

Morbidelli, L. ^{[2
]}

Sbordone, L. ^{[15
,16
]}

Mikolaitis, S. ^{[17
]}

Ryde, N. ^{[3
]}

机构：

[1] Univ Cambridge, Inst Astron, Cambridge CB3 0HA, England

[2] INAF Osserv Astrofis Arcetri, I-50125 Florence, Italy

[3] Lund Observ, Dept Astron & Theoret Phys, SE-22100 Lund, Sweden

[4] INAF Osserv Astron Bologna, I-40127 Bologna, Italy

[5] Max Planck Inst Astron, D-69117 Heidelberg, Germany

[6] European So Observ, Santiago, Chile

[7] Inst Astrofis Andalucia CSIC, E-18080 Granada, Spain

[8] INAF Osserv Astron Palermo, I-90134 Palermo, Italy

[9] Univ Paris Diderot, GEPI, Observ Paris, CNRS, F-92190 Meudon, France

[10] Uppsala Univ, Dept Phys & Astron, SE-75120 Uppsala, Sweden

[11] Univ Nice Sophia Antipolis, Lab Lagranff UMR7293, CNRS, Observ Cote Azur, F-06304 Nice 4, France

[12] Liverpool John Moores Univ, Astrophys Res Inst, Liverpool L3 5RF, Merseyside, England

[13] Univ Catania, Dipartimento Fis & Astron, Sez Astrofis, I-95123 Catania, Italy

[14] Univ Andres Bello, Dept Ciencias Fis, Santiago, Chile

[15] Millennium Inst Astrophys, Santiago 7820436, Chile

[16] Pontificia Univ Catolica Chile, Santiago 7820436, Chile

[17] Vilnius Univ, Inst Theoret Phys & Astron, LT-01108 Vilnius, Lithuania

来源：

ASTROPHYSICAL JOURNAL | 2015年 / 811卷 / 01期

基金：

英国科学技术设施理事会;

关键词：

galaxies: abundances; galaxies: dwarf; galaxies: kinematics and dynamics; Galaxy: halo; globular clusters: general; stars: abundances; MILKY-WAY SATELLITE; EXPLORING HALO SUBSTRUCTURE; ULTRA-FAINT SATELLITES; MAGELLANIC STREAM; STAR CLUSTER; GIANT STARS; SPECTROSCOPIC SURVEY; STELLAR KINEMATICS; SPHEROIDAL GALAXY; HORSE DISCOVERY;

D O I：

10.1088/0004-637X/811/1/62

中图分类号：

P1 [天文学];

学科分类号：

0704 ;

摘要：

We report on VLT/GIRAFFE spectra of stars in two recently discovered ultra-faint satellites, Reticulum 2 and Horologium 1, obtained as part of the Gaia-ESO Survey. We identify 18 members in Reticulum 2 and five in Horologium 1. We find Reticulum 2 to have a velocity dispersion of 3.22(-0.49)(+1.64) km s(-1) , implying a mass-to-light ratio (M/L) of similar to 500. The mean metallicity of Reticulum 2 is [Fe/H] = -2.46, with an intrinsic dispersion of similar to 0.3 dex and alpha-enhancement of similar to 0.4 dex. We conclude that Reticulum 2 is a dwarf galaxy. We also report on the serendipitous discovery of four stars in a previously unknown stellar substructure near Reticulum 2 with [Fe/H] similar to -2 and V-hel similar to 220 km s(-1), far from the systemic velocity of Reticulum 2. For Horologium 1 we infer a velocity dispersion of sigma (V) = 4.9(-0.9)(+2.8) km s(-1) and a M/L ratio of similar to 600, leading us to conclude that Horologium 1 is also a dwarf galaxy. Horologium 1 is slightly more metal-poor than Reticulum 2 ([Fe/H] = -2.76) and is similarly alpha-enhanced: [alpha/Fe] similar to 0.3 dex with a significant spread of metallicities of 0.17 dex. The line-of-sight velocity of Reticulum 2 is offset by 100 km s(-1) from the prediction of the orbital velocity of the Large Magellanic Cloud (LMC), thus making its association with the Cloud uncertain. However, at the location of Horologium 1, both the backward-integrated orbit of the LMC and its halo are predicted to have radial velocities similar to that of the dwarf. Therefore, it is possible that Horologium 1 is or once was a member of the Magellanic family.

引用

页数：14

共 90 条

[1] THE SEVENTH DATA RELEASE OF THE SLOAN DIGITAL SKY SURVEY [J].

Abazajian, Kevork N. ;

Adelman-McCarthy, Jennifer K. ;

Agueros, Marcel A. ;

Allam, Sahar S. ;

Prieto, Carlos Allende ;

An, Deokkeun ;

Anderson, Kurt S. J. ;

Anderson, Scott F. ;

Annis, James ;

Bahcall, Neta A. ;

Bailer-Jones, C. A. L. ;

Barentine, J. C. ;

Bassett, Bruce A. ;

Becker, Andrew C. ;

Beers, Timothy C. ;

Bell, Eric F. ;

Belokurov, Vasily ;

Berlind, Andreas A. ;

Berman, Eileen F. ;

Bernardi, Mariangela ;

Bickerton, Steven J. ;

Bizyaev, Dmitry ;

Blakeslee, John P. ;

Blanton, Michael R. ;

Bochanski, John J. ;

Boroski, William N. ;

Brewington, Howard J. ;

Brinchmann, Jarle ;

Brinkmann, J. ;

Brunner, Robert J. ;

Budavari, Tamas ;

Carey, Larry N. ;

Carliles, Samuel ;

Carr, Michael A. ;

Castander, Francisco J. ;

Cinabro, David ;

Connolly, A. J. ;

Csabai, Istvan ;

Cunha, Carlos E. ;

Czarapata, Paul C. ;

Davenport, James R. A. ;

de Haas, Ernst ;

Dilday, Ben ;

Doi, Mamoru ;

Eisenstein, Daniel J. ;

Evans, Michael L. ;

Evans, N. W. ;

Fan, Xiaohui ;

Friedman, Scott D. ;

Frieman, Joshua A. .

ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES, 2009, 182 (02) :543-558

[2]

Alam S., 2015, ARXIV150100963

[3]

Alvarez R, 1998, ASTRON ASTROPHYS, V330, P1109

[4]

Astropy Collaboration, 2013, A A, V558, pAA33

[5] A NEW MILKY WAY HALO STAR CLUSTER IN THE SOUTHERN GALACTIC SKY [J].

Balbinot, E. ;

Santiago, B. X. ;

da Costa, L. ;

Maia, M. A. G. ;

Majewski, S. R. ;

Nidever, D. ;

Rocha-Pinto, H. J. ;

Thomas, D. ;

Wechsler, R. H. ;

Yanny, B. .

ASTROPHYSICAL JOURNAL, 2013, 767 (02)

[6] EIGHT NEW MILKY WAY COMPANIONS DISCOVERED IN FIRST-YEAR DARK ENERGY SURVEY DATA [J].

Bechtol, K. ;

Drlica-Wagner, A. ;

Balbinot, E. ;

Pieres, A. ;

Simon, J. D. ;

Yanny, B. ;

Santiago, B. ;

Wechsler, R. H. ;

Frieman, J. ;

Walker, A. R. ;

Williams, P. ;

Rozo, E. ;

Rykoff, E. S. ;

Queiroz, A. ;

Luque, E. ;

Benoit-Levy, A. ;

Tucker, D. ;

Sevilla, I. ;

Gruendl, R. A. ;

da Costa, L. N. ;

Fausti Neto, A. ;

Maia, M. A. G. ;

Abbott, T. ;

Allam, S. ;

Armstrong, R. ;

Bauer, A. H. ;

Bernstein, G. M. ;

Bernstein, R. A. ;

Bertin, E. ;

Brooks, D. ;

Buckley-Geer, E. ;

Burke, D. L. ;

Carnero Rosell, A. ;

Castander, F. J. ;

Covarrubias, R. ;

D'Andrea, C. B. ;

DePoy, D. L. ;

Desai, S. ;

Diehl, H. T. ;

Eifler, T. F. ;

Estrada, J. ;

Evrard, A. E. ;

Fernandez, E. ;

Finley, D. A. ;

Flaugher, B. ;

Gaztanaga, E. ;

Gerdes, D. ;

Girardi, L. ;

Gladders, M. ;

Gruen, D. .

ASTROPHYSICAL JOURNAL, 2015, 807 (01)

[7] LEO V: A COMPANION OF A COMPANION OF THE MILKY WAY GALAXY? [J].

Belokurov, V. ;

Walker, M. G. ;

Evans, N. W. ;

Faria, D. C. ;

Gilmore, G. ;

Irwin, M. J. ;

Koposov, S. ;

Mateo, M. ;

Olszewski, E. ;

Zucker, D. B. .

ASTROPHYSICAL JOURNAL LETTERS, 2008, 686 (02) :L83-L86

[8] An orphan in the "Field of Streams" [J].

Belokurov, V. ;

Evans, N. W. ;

Irwin, M. J. ;

Lynden-Bell, D. ;

Yanny, B. ;

Vidrih, S. ;

Gilmore, G. ;

Seabroke, G. ;

Zucker, D. B. ;

Wilkinson, M. I. ;

Hewett, P. C. ;

Bramich, D. M. ;

Fellhauer, M. ;

Newberg, H. J. ;

Wyse, R. F. G. ;

Beers, T. C. ;

Bell, E. F. ;

Barentine, J. C. ;

Brinkmann, J. ;

Cole, N. ;

Pan, K. ;

York, D. G. .

ASTROPHYSICAL JOURNAL, 2007, 658 (01) :337-344

[9] Cats and dogs, hair and a hero: A quintet of new Milky Way companions [J].

Belokurov, V. ;

Zucker, D. B. ;

Evans, N. W. ;

Kleyna, J. T. ;

Koposov, S. ;

Hodgkin, S. T. ;

Irwin, M. J. ;

Gilmore, G. ;

Wilkinson, M. I. ;

Fellhauer, M. ;

Bramich, D. M. ;

Hewett, P. C. ;

Vidrih, S. ;

De Jong, J. T. A. ;

Smith, J. A. ;

Rix, H. -W. ;

Bell, E. F. ;

Wyse, R. F. G. ;

Newberg, H. J. ;

Mayeur, P. A. ;

Yanny, B. ;

Rockosi, C. M. ;

Gnedin, O. Y. ;

Schneider, D. P. ;

Beers, T. C. ;

Barentine, J. C. ;

Brewington, H. ;

Brinkmann, J. ;

Harvanek, M. ;

Kleinman, S. J. ;

Krzesinski, J. ;

Long, D. ;

Nitta, A. ;

Snedden, S. A. .

ASTROPHYSICAL JOURNAL, 2007, 654 (02) :897-906

[10] A faint new milky way satellite in Bootes [J].

Belokurov, V. ;

Zucker, D. B. ;

Evans, N. W. ;

Wilkinson, M. I. ;

Irwin, M. J. ;

Hodgkin, S. ;

Bramich, D. M. ;

Irwin, J. M. ;

Gilmore, G. ;

Willman, B. ;

Vidrih, S. ;

Newberg, H. J. ;

Wyse, R. F. G. ;

Fellhauer, M. ;

Hewett, P. C. ;

Cole, N. ;

Bell, E. F. ;

Beers, T. C. ;

Rockosi, C. M. ;

Yanny, B. ;

Grebel, E. K. ;

Schneider, D. P. ;

Lupton, R. ;

Barentine, J. C. ;

Brewington, H. ;

Brinkmann, J. ;

Harvanek, M. ;

Kleinman, S. J. ;

Krzesinski, J. ;

Long, D. ;

Nitta, A. ;

Smith, J. A. ;

Snedden, S. A. .

ASTROPHYSICAL JOURNAL, 2006, 647 (02) :L111-L114

← 1 2 3 4 5 6 7 8 9 →