TY - JOUR

T1 - Investigating the origin and spectroscopic variability of the near-infrared HI lines in the Herbig star VV Ser

AU - Lopez, Rebeca Garcia

AU - Kurosawa, Ryuichi

AU - Garatti o Carattio, Alessio

AU - Kreplin, Alexander

AU - Weigelt, Gerd

AU - Tambovtseva, Larisa V.

AU - Grinin, Vladimir P.

AU - Ray, Thomas P.

N1 - Publisher Copyright: © 2015 The Authors.

PY - 2016/2/11

Y1 - 2016/2/11

N2 - The origin of the near-infrared (NIR) HI emission lines in young stellar objects are not yet understood. To probe it, we present multi-epoch LBT-LUCIFER spectroscopic observations of the Paδ, Paβ, and Brγ lines observed in the Herbig star VV Ser, along with Very Large Telescope Interferometer-AMBER Br? spectro-interferometric observations at medium resolution. Our spectroscopic observations show line profile variability in all the HI lines. The strongest variability is observed in the redshifted part of the line profiles. The Br? spectrointerferometric observations indicate that the Br? line emitting region is smaller than the continuum emitting region. To interpret our results, we employed radiative transfer models with three different flow configurations: magnetospheric accretion, a magnetocentrifugally driven disc wind, and a schematic bipolar outflow. Our models suggest that the HI line emission inVVSer is dominated by the contribution of an extended wind, perhaps a bipolar outflow. Although the exact physical process for producing such outflow is not known, this model is capable of reproducing the averaged single-peaked line profiles of the HI lines. Additionally, the observed visibilities, differential and closure phases are best reproduced when a wind is considered. Nevertheless, the complex line profiles and variability could be explained by changes in the relative contribution of the magnetosphere and/or winds to the line emission. This might indicate that the NIR HI lines are formed in a complex inner disc region where inflow and outflow components might coexist. Furthermore, the contribution of each of these mechanisms to the line appears time variable, suggesting a non-steady accretion/ejection flow.

AB - The origin of the near-infrared (NIR) HI emission lines in young stellar objects are not yet understood. To probe it, we present multi-epoch LBT-LUCIFER spectroscopic observations of the Paδ, Paβ, and Brγ lines observed in the Herbig star VV Ser, along with Very Large Telescope Interferometer-AMBER Br? spectro-interferometric observations at medium resolution. Our spectroscopic observations show line profile variability in all the HI lines. The strongest variability is observed in the redshifted part of the line profiles. The Br? spectrointerferometric observations indicate that the Br? line emitting region is smaller than the continuum emitting region. To interpret our results, we employed radiative transfer models with three different flow configurations: magnetospheric accretion, a magnetocentrifugally driven disc wind, and a schematic bipolar outflow. Our models suggest that the HI line emission inVVSer is dominated by the contribution of an extended wind, perhaps a bipolar outflow. Although the exact physical process for producing such outflow is not known, this model is capable of reproducing the averaged single-peaked line profiles of the HI lines. Additionally, the observed visibilities, differential and closure phases are best reproduced when a wind is considered. Nevertheless, the complex line profiles and variability could be explained by changes in the relative contribution of the magnetosphere and/or winds to the line emission. This might indicate that the NIR HI lines are formed in a complex inner disc region where inflow and outflow components might coexist. Furthermore, the contribution of each of these mechanisms to the line appears time variable, suggesting a non-steady accretion/ejection flow.

KW - Circumstellar matter

KW - Infrared: stars

KW - Stars: protostars

KW - Stars: variables: T Tauri, Herbig Ae/Be

KW - Stars: winds, outflows

KW - Techniques: interferometric

UR - http://www.scopus.com/inward/record.url?scp=84959498156&partnerID=8YFLogxK

U2 - 10.1093/mnras/stv2664

DO - 10.1093/mnras/stv2664

M3 - Article

AN - SCOPUS:84959498156

VL - 456

SP - 156

EP - 170

JO - Monthly Notices of the Royal Astronomical Society

JF - Monthly Notices of the Royal Astronomical Society

SN - 0035-8711

IS - 1

ER -