TY - JOUR

T1 - First NIR interferometrically resolved high-order Brackett and forbidden Fe lines of a B[e] star

T2 - V921 Sco

AU - Kreplin, Alexander

AU - Kraus, Stefan

AU - Tambovtseva, Larisa

AU - Grinin, Vladimir

AU - Hone, Edward

N1 - Publisher Copyright: © 2019 The Author(s).

PY - 2020/2/1

Y1 - 2020/2/1

N2 - We present near-infrared interferometric AMBER observations of the B[e] binary V921 Sco at low (R ~ 30) and medium spectral resolution (R ~ 1500) in the K and H bands. Low spectral resolution AMBER data were used to estimate the position of the companion V921 Sco B and confirmed a clockwise movement on sky with respect to the primary of 33? between 2008 and 2012. Our observations resolve for the first time higher order Brackett lines (Br6-Br12). The modelling of the different line transitions revealed a decrease in the size of the line-emitting regions from Br3 to Br12. We are able to reproduce this decrease with a simple radiative transfer model of an equatorial disc in local thermodynamic equilibrium. In addition to the Brackett series, we also resolve permitted and forbidden Fe line emission. Our modelling shows that these lines originate from ~2 au from the star, corresponding roughly to the measured dust sublimation region. This might indicate that the forbidden line emission arises from shock excitation at the base of a disc wind.

AB - We present near-infrared interferometric AMBER observations of the B[e] binary V921 Sco at low (R ~ 30) and medium spectral resolution (R ~ 1500) in the K and H bands. Low spectral resolution AMBER data were used to estimate the position of the companion V921 Sco B and confirmed a clockwise movement on sky with respect to the primary of 33? between 2008 and 2012. Our observations resolve for the first time higher order Brackett lines (Br6-Br12). The modelling of the different line transitions revealed a decrease in the size of the line-emitting regions from Br3 to Br12. We are able to reproduce this decrease with a simple radiative transfer model of an equatorial disc in local thermodynamic equilibrium. In addition to the Brackett series, we also resolve permitted and forbidden Fe line emission. Our modelling shows that these lines originate from ~2 au from the star, corresponding roughly to the measured dust sublimation region. This might indicate that the forbidden line emission arises from shock excitation at the base of a disc wind.

KW - Circumstellar matter

KW - Stars: emission-line, Be

KW - Stars: formation

KW - Stars: individual: V921 Sco

KW - Stars: pre-main-sequence

KW - Techniques: interferometric

UR - http://www.scopus.com/inward/record.url?scp=85079465186&partnerID=8YFLogxK

U2 - 10.1093/mnras/stz3346

DO - 10.1093/mnras/stz3346

M3 - Article

VL - 492

SP - 566

EP - 571

JO - Monthly Notices of the Royal Astronomical Society

JF - Monthly Notices of the Royal Astronomical Society

SN - 0035-8711

IS - 1

ER -