TY - JOUR
T1 - Pre-main-sequence Brackett Emitters in the APOGEE DR17 Catalog
T2 - Line Strengths and Physical Properties of Accretion Columns
AU - Campbell, Hunter
AU - Khilfeh, Elliott
AU - Covey, Kevin R.
AU - Kounkel, Marina
AU - Ballantyne, Richard
AU - Corey, Sabrina
AU - Román-Zúñiga, Carlos G.
AU - Hernández, Jesús
AU - Martínez, Ezequiel Manzo
AU - Ramírez, Karla Peña
AU - Roman-Lopes, Alexandre
AU - Stassun, Keivan G.
AU - Stringfellow, Guy S.
AU - Borissova, Jura
AU - Chojnowski, S. Drew
AU - Ramírez-Preciado, Valeria
AU - Kim, Jinyoung Serena
AU - Serna, Javier
AU - Stutz, Amelia M.
AU - López-Valdivia, Ricardo
AU - Suárez, Genaro
AU - Ybarra, Jason E.
AU - Longa-Peña, Penélope
AU - Fernández-Trincado, José G.
N1 - Publisher Copyright:
© 2022. The Author(s). Published by the American Astronomical Society.
PY - 2023/1/1
Y1 - 2023/1/1
N2 - Very young (t ≲ 10 Myr) stars possess strong magnetic fields that channel ionized gas from the interiors of their circumstellar disks to the surface of the star. Upon impacting the stellar surface, the shocked gas recombines and emits hydrogen spectral lines. To characterize the density and temperature of the gas within these accretion streams, we measure equivalent widths of Brackett (Br) 11-20 emission lines detected in 1101 APOGEE spectra of 326 likely pre-main-sequence accretors. For sources with multiple observations, we measure median epoch-to-epoch line strength variations of 10% in Br11 and 20% in Br20. We also fit the measured line ratios to predictions of radiative transfer models by Kwan & Fischer. We find characteristic best-fit electron densities of n e = 1011-1012 cm−3, and excitation temperatures that are inversely correlated with electron density (from T ∼ 5000 K for n e ∼ 1012 cm−3 to T ∼ 12,500 K at n e ∼ 1011 cm−3). These physical parameters are in good agreement with predictions from modeling of accretion streams that account for the hydrodynamics and radiative transfer within the accretion stream. We also present a supplementary catalog of line measurements from 9733 spectra of 4255 Brackett emission-line sources in the APOGEE Data Release 17 data set.
AB - Very young (t ≲ 10 Myr) stars possess strong magnetic fields that channel ionized gas from the interiors of their circumstellar disks to the surface of the star. Upon impacting the stellar surface, the shocked gas recombines and emits hydrogen spectral lines. To characterize the density and temperature of the gas within these accretion streams, we measure equivalent widths of Brackett (Br) 11-20 emission lines detected in 1101 APOGEE spectra of 326 likely pre-main-sequence accretors. For sources with multiple observations, we measure median epoch-to-epoch line strength variations of 10% in Br11 and 20% in Br20. We also fit the measured line ratios to predictions of radiative transfer models by Kwan & Fischer. We find characteristic best-fit electron densities of n e = 1011-1012 cm−3, and excitation temperatures that are inversely correlated with electron density (from T ∼ 5000 K for n e ∼ 1012 cm−3 to T ∼ 12,500 K at n e ∼ 1011 cm−3). These physical parameters are in good agreement with predictions from modeling of accretion streams that account for the hydrodynamics and radiative transfer within the accretion stream. We also present a supplementary catalog of line measurements from 9733 spectra of 4255 Brackett emission-line sources in the APOGEE Data Release 17 data set.
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U2 - 10.3847/1538-4357/aca324
DO - 10.3847/1538-4357/aca324
M3 - Article
AN - SCOPUS:85145677274
SN - 0004-637X
VL - 942
JO - Astrophysical Journal
JF - Astrophysical Journal
IS - 1
M1 - 22
ER -