The GALAH survey: verifying abundance trends in the open cluster M67 using non-LTE modelling

被引：46

作者：

Gao, Xudong ^{[1
,2
]}

Lind, Karin ^{[1
,3
]}

Amarsi, Anish M. ^{[1
]}

Buder, Sven ^{[1
,2
]}

Dotter, Aaron ^{[4
]}

Nordlander, Thomas ^{[5
,6
]}

Asplund, Martin ^{[5
,6
]}

Bland-Hawthorn, Joss ^{[6
,7
,8
]}

De Silva, Gayandhi M. ^{[6
,9
]}

D'Orazi, Valentina ^{[10
]}

Freeman, Ken C. ^{[5
]}

Kos, Janez ^{[7
]}

Lewis, Geraint F. ^{[7
]}

Lin, Jane ^{[5
,6
]}

Martell, Sarah L. ^{[6
,11
]}

Schlesinger, Katharine J. ^{[5
]}

Sharma, Sanjib ^{[6
,7
]}

Simpson, Jeffrey D. ^{[11
]}

Zucker, Daniel B. ^{[9
,12
]}

Zwitter, Tomaz ^{[13
]}

Da Costa, Gary ^{[5
]}

Anguiano, Borja ^{[14
]}

Horner, Jonathan ^{[15
]}

Hyde, Elaina A. ^{[16
]}

Kafle, Prajwal R. ^{[17
]}

Nataf, David M. ^{[18
]}

Reid, Warren ^{[12
,16
]}

Stello, Dennis ^{[6
,12
,19
]}

Ting, Yuan-Sen ^{[20
,21
,22
]}

机构：

[1] Max Planck Inst Astron, Konigstuhl 17, D-69117 Heidelberg, Germany

[2] Heidelberg Univ, Int Max Planck Res Sch Astron & Cosm Phys, Heidelberg, Germany

[3] Uppsala Univ, Dept Phys & Astron, Box 516, SE-75120 Uppsala, Sweden

[4] Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA

[5] Australian Natl Univ, Mt Stromlo Observ, Res Sch Astron & Astrophys, Weston, ACT 2611, Australia

[6] Ctr Excellence Astrophys Three Dimens ASTRO 3D, Canberra, ACT 2611, Australia

[7] Univ Sydney, Sch Phys, Sydney Inst Astron SIfA, A28, Sydney, NSW 2006, Australia

[8] Univ Calif Berkeley, Miller Inst, Berkeley, CA 94720 USA

[9] Australian Astron Observ, 105 Delhi Rd, N Ryde, NSW 2113, Australia

[10] Osserv Astron Padova, Ist Nazl Astrofis, Vicolo Osservatorio 5, I-35122 Padua, Italy

[11] Univ New South Wales, Sch Phys, Sydney, NSW 2052, Australia

[12] Macquarie Univ, Dept Phys & Astron, Sydney, NSW 2109, Australia

[13] Univ Ljubljana, Fac Math & Phys, Jadranska 19, Ljubljana 1000, Slovenia

[14] Univ Virginia, Dept Astron, POB 400325, Charlottesville, VA 22904 USA

[15] Univ Southern Queensland, Toowoomba, Qld 4350, Australia

[16] Western Sydney Univ, Locked Bag 1797, Penrith, NSW 1797, Australia

[17] Univ Western Australia, ICRAR, 35 Stirling Highway, Crawley, WA 6009, Australia

[18] Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA

[19] Aarhus Univ, Dept Phys & Astron, Stellar Astrophys Ctr, DK-8000 Aarhus C, Denmark

[20] Inst Adv Study, Princeton, NJ 08540 USA

[21] Princeton Univ, Dept Astrophys Sci, Princeton, NJ 08544 USA

[22] Observ Carnegie Inst Washington, 813 Santa Barbara St, Pasadena, CA 91101 USA

来源：

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY | 2018年 / 481卷 / 02期

基金：

澳大利亚研究理事会; 瑞典研究理事会;

关键词：

radiative transfer; stars: abundances; stars: atmospheres; stars: late-type; LATE-TYPE STARS; OXYGEN LINE FORMATION; CHEMICAL HOMOGENEITY; STELLAR EVOLUTION; ATOMIC DATA; LITHIUM; FE; SUN; METALLICITY; CONSTRAINTS;

D O I：

10.1093/mnras/sty2414

中图分类号：

P1 [天文学];

学科分类号：

0704 ;

摘要：

Open cluster members are coeval and share the same initial bulk chemical composition. Consequently, differences in surface abundances between members of a cluster that are at different evolutionary stages can be used to study the effects of mixing and internal chemical processing. We carry out an abundance analysis of seven elements (Li, O, Na, Mg, Al, Si, and Fe) in 66 stars belonging to the open cluster m67, based on high resolution GALAH spectra, 1D MARCS model atmospheres, and non-local thermodynamic equilibrium (non-LTE) radiative transfer. From the non-LTE analysis, we find a typical star-to-star scatter in the abundance ratios of around O.05 dex. We find trends in the abundance ratios with effective temperature, indicating systematic differences in the surface abundances between turn-off and giant stars; these trends are more pronounced when LTE is assumed. However, trends with effective temperature remain significant for Al and Si also in non-LTE. Finally, we compare the derived abundances with prediction from stellar evolution models including effects of atomic diffusion. We find overall good agreement for the abundance patterns of dwarfs and sub-giant stars, but the abundances of cool giants are lower relative to less evolved stars than predicted by the diffusion models, in particular for Mg.

引用

页码：2666 / 2684

页数：19

共 109 条

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