Dynamically Tagged Groups of Very Metal-poor Halo Stars from the HK and Hamburg/ESO Surveys

Autor(es):Mostrar menos -

Limberg, Guilherme ^[1] ; Rossi, Silvia ^[1] ; Beers, Timothy C. ^{[2, 3]} ; Perottoni, Helio D. ^[1] ; Perez-Villegas, Angeles ^{[1, 4]} ; Santucci, Rafael M. ^{[5, 6]} ; Abuchaim, Yuri ^[1] ; Placco, Vinicius M. ^[7] ; Lee, Young Sun ^[8] ; Christlieb, Norbert ^[9] ; Norris, John E. ^[10] ; Bessell, Michael S. ^[10] ; Ryan, Sean G. ^[11] ; Wilhelm, Ronald ^[12] ; Rhee, Jaehyon ^[13] ; Frebel, Anna ^{[14, 15]}

Afiliação do(s) autor(es):Mostrar menos -

^[1] Univ Sao Paulo, Inst Astron Geofis & Ciencias Atmosfer, Dept Astron, BR-05508090 Sao Paulo, SP - Brazil

^[2] Univ Notre Dame, Dept Phys, Notre Dame, IN 46556 - USA

^[3] Univ Notre Dame, JINA Ctr Evolut Elements, Notre Dame, IN 46556 - USA

^[4] Univ Nacl Autonoma Mexico, Inst Astron, Apartado Postal 106, Ensenada 22800, Baja California - Mexico

^[5] Univ Fed Goias, Inst Fis, BR-74001970 Goiania, Go - Brazil

^[6] Univ Fed Goias, Inst Estudos Socioambientais, BR-74055140 Goiania, Go - Brazil

^[7] NSFs Natl Opt Infrared Astron Res Lab, Tucson, AZ 85719 - USA

^[8] Chungnam Natl Univ, Dept Astron & Space Sci, Daejeon 34134 - South Korea

^[9] Heidelberg Univ, Zentrum Astron, Landessternwarte, D-69117 Heidelberg - Germany

^[10] Australian Natl Univ, Res Sch Astron & Astrophys, Canberra, ACT 2611 - Australia

^[11] Univ Hertfordshire, Sch Phys Astron & Math, Coll Lane, Hatfield AL10 9AB, Herts - England

^[12] Univ Kentucky, Dept Phys & Astron, Lexington, KY 40506 - USA

^[13] Harvard & Smithsonian, Ctr Astrophys, 60 Garden St, MS-09, Cambridge, MA 02138 - USA

^[14] MIT, Dept Phys, Cambridge, MA 02139 - USA

^[15] MIT, Kavli Inst Astrophys & Space Res, Cambridge, MA 02139 - USA

• Tipo de documento: Artigo Científico
• Fonte: ASTROPHYSICAL JOURNAL; v. 907, n. 1 JAN 2021.
• Citações Web of Science: 2

Resumo

We analyze the dynamical properties of similar to 1500 very metal-poor (VMP; {[}Fe/H] less than or similar to -2.0) halo stars, based primarily on medium-resolution spectroscopic data from the HK and Hamburg/ESO surveys. These data, collected over the past 30 yr, are supplemented by a number of calibration stars and other small samples, along with astrometric information from Gaia DR2. We apply a clustering algorithm to the 4D energy-action space of the sample, and identify a set of 38 dynamically tagged groups (DTGs), containing between 5 and 30 member stars. Many of these DTGs can be associated with previously known prominent substructures such as Gaia-Sausage/Enceladus (GSE), Sequoia, Helmi Stream (HStr), and Thamnos. Others are associated with previously identified smaller dynamical groups of stars and streams. We identify 10 new DTGs as well, many of which have strongly retrograde orbits. We also investigate possible connections between our DTGs and similar to 300 individual r-process-enhanced (RPE) stars from a recent literature compilation. We find that several of these objects have similar dynamical properties to GSE (5), the HStr (4), Sequoia (1), and Rg5 (1), indicating that their progenitors might have been important sources of RPE stars in the Galaxy. Additionally, a number of our newly identified DTGs are shown to be associated with at least two RPE stars each (DTG-2: 3, DTG-7: 2; DTG-27: 2). Taken as a whole, these results are consistent with ultra-faint and/or dwarf spheroidal galaxies as birth environments in which r-process nucleosynthesis took place, and then were disrupted by the Milky Way. (AU)

• Processo FAPESP: 17/15893-1 - Órbitas de aglomerados globulares do bojo: formação e evolução da Via Láctea
• Beneficiário: Maria de Los Angeles Perez Villegas
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado
• Processo FAPESP: 14/18100-4 - Populações estelares na Via Láctea: bojo, halo, disco e regiões de formação de estrelas; instrumentação para espectroscopia de alta resolução
• Beneficiário: Beatriz Leonor Silveira Barbuy
• Modalidade de apoio: Auxílio à Pesquisa - Temático
• Processo FAPESP: 18/21250-9 - Identificação de estrelas brilhantes pobres em metais a partir de fotometria Multi-Banda e acompanhamento espectroscópico
• Beneficiário: Hélio Dotto Perottoni
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado
• Processo FAPESP: 15/50374-0 - Mosaic: the multi-object spectrograph for the ESO Extremely Large Telescope
• Beneficiário: Silvia Cristina Fernandes Rossi
• Modalidade de apoio: Auxílio à Pesquisa - Temático