How Magnetic Activity Alters What We Learn from Stellar Spectra

Autor(es):Mostrar menos -

Spina, Lorenzo ^{[1, 2]} ; Nordlander, Thomas ^{[3, 2]} ; Casey, Andrew R. ^{[1, 2]} ; Bedell, Megan ^[4] ; D'Orazi, Valentina ^[5] ; Melendez, Jorge ^[6] ; Karakas, I, Amanda ; Desidera, Silvano ^[5] ; Baratella, Martina ^{[5, 7]} ; Yana Galarza, Jhon J. ^[6] ; Casali, Giada ^{[8, 9, 10]}

Afiliação do(s) autor(es)

^[1] Monash Univ, Sch Phys & Astron, Clayton, Vic 3800 - Australia

^[2] I, ARC Ctr Excellence All Sky Astrophys 3 Dimens AST, Sydney, NSW - Australia

^[3] Australian Natl Univ, Res Sch Astron & Astrophys, Canberra, ACT 2611 - Australia

^[4] Simons Fdn, Flatiron Inst, 162 Fifth Ave, New York, NY 10010 - USA

^[5] INAF Astron Observ Padua, Vicolo Osservatorio 5, I-35122 Padua - Italy

^[6] Univ Sao Paulo, Dept Astron, IAG, Rua Matao 1226, BR-05509900 Sao Paulo, SP - Brazil

^[7] Univ Padua, Dept Phys & Astron Galileo Galilei, Vicolo Osservatorio 3, I-35122 Padua - Italy

^[8] Karakas, Amanda, I, Monash Univ, Sch Phys & Astron, Clayton, Vic 3800 - Australia

^[9] INAF Arcetri Astrophys Observ, Largo E Fermi 5, I-50125 Florence - Italy

^[10] Univ Florence, Dept Phys & Astron, Via G Sansone 1, I-50019 Florence - Italy

• Tipo de documento: Artigo Científico
• Fonte: ASTROPHYSICAL JOURNAL; v. 895, n. 1 MAY 2020.
• Citações Web of Science: 0

Resumo

Magnetic fields and stellar spots can alter the equivalent widths of absorption lines in stellar spectra, varying during the activity cycle. This also influences the information that we derive through spectroscopic analysis. In this study, we analyze high-resolution spectra of 211 sunlike stars observed at different phases of their activity cycles, in order to investigate how stellar activity affects the spectroscopic determination of stellar parameters and chemical abundances. We observe that the equivalent widths of lines can increase as a function of the activity index log R-HK' during the stellar cycle, which also produces an artificial growth of the stellar microturbulence and a decrease in effective temperature and metallicity. This effect is visible for stars with activity indexes log R-HK' >= -5.0 (i.e., younger than 4-5 Gyr), and it is more significant at higher activity levels. These results have fundamental implications on several topics in astrophysics that are discussed in the paper, including stellar nucleosynthesis, chemical tagging, the study of Galactic chemical evolution, chemically anomalous stars, the structure of the Milky Way disk, stellar formation rates, photoevaporation of circumstellar disks, and planet hunting. (AU)

• Processo FAPESP: 18/04055-8 - Espectroscopia de alta precisão: das primeiras estrelas aos planetas
• Beneficiário: Jorge Luis Melendez Moreno
• Linha de fomento: Auxílio à Pesquisa - Temático