TY - JOUR

T1 - B fields in OB stars (BOB)

T2 - the magnetic triple stellar system HD 164492C in the Trifid nebula

AU - Gonzalez, J. F.

AU - Hubrig, S.

AU - Przybilla, N.

AU - Carroll, T.

AU - Nieva, M. -F.

AU - Ilyin, I.

AU - Jaervinen, S.

AU - Morel, T.

AU - Schoeller, M.

AU - Castro, N.

AU - Barba, R.

AU - de Koter, A.

AU - Schneider, F. R. N.

AU - Kholtygin, A.

AU - Butler, K.

AU - Veramendi, M. E.

AU - Langer, N.

AU - BOB Collaboration

PY - 2017/5

Y1 - 2017/5

N2 - HD 164492C is a spectroscopic triple stellar system that has been recently detected to possess a strong magnetic field. We have obtained high-resolution spectroscopic and spectropolarimetric observations over a time span of two years and derived physical, chemical and magnetic properties for this object. The system is formed by an eccentric close spectroscopic binary (Ca1-Ca2) with a period of 12.5 d, and a massive tertiary Cb. We calculated the orbital parameters of the close pair, reconstructed the spectra of the three components and determined atmospheric parameters and chemical abundances by spectral synthesis. From spectropolarimetric observations, multi-epoch measurements of the longitudinal magnetic fields were obtained. The magnetic field is strongly variable on time-scales of a few days, with a most probable period in the range of 1.4-1.6 d. Star Cb with Teff ˜ 25 000 K is apparently the fastest rotator and the most massive star of this triple system and has anomalous chemical abundances with a marked overabundance of helium, 0.35±0.04 by number. We identified this star as being responsible for the observed magnetic field, although the presence of magnetic fields in the components of the Ca pair cannot be excluded. Star Ca1 with a temperature of about 24 000 K presents a normal chemical pattern, while the least massive star Ca2 is a mid-B-type star (Teff ˜ 15 000 K) with an overabundance of silicon. The obtained stellar parameters of the system components suggest a distance of 1.5 kpc and an age of 10-15 Myr.

AB - HD 164492C is a spectroscopic triple stellar system that has been recently detected to possess a strong magnetic field. We have obtained high-resolution spectroscopic and spectropolarimetric observations over a time span of two years and derived physical, chemical and magnetic properties for this object. The system is formed by an eccentric close spectroscopic binary (Ca1-Ca2) with a period of 12.5 d, and a massive tertiary Cb. We calculated the orbital parameters of the close pair, reconstructed the spectra of the three components and determined atmospheric parameters and chemical abundances by spectral synthesis. From spectropolarimetric observations, multi-epoch measurements of the longitudinal magnetic fields were obtained. The magnetic field is strongly variable on time-scales of a few days, with a most probable period in the range of 1.4-1.6 d. Star Cb with Teff ˜ 25 000 K is apparently the fastest rotator and the most massive star of this triple system and has anomalous chemical abundances with a marked overabundance of helium, 0.35±0.04 by number. We identified this star as being responsible for the observed magnetic field, although the presence of magnetic fields in the components of the Ca pair cannot be excluded. Star Ca1 with a temperature of about 24 000 K presents a normal chemical pattern, while the least massive star Ca2 is a mid-B-type star (Teff ˜ 15 000 K) with an overabundance of silicon. The obtained stellar parameters of the system components suggest a distance of 1.5 kpc and an age of 10-15 Myr.

KW - LTE LINE-FORMATION

KW - A-TYPE STARS

KW - MODEL ATOM

KW - ABUNDANCES

KW - PARAMETERS

KW - BINARY

KW - GENERATION

KW - HYDROGEN

KW - BRIGHT

KW - OXYGEN

U2 - 10.1093/mnras/stx105

DO - 10.1093/mnras/stx105

M3 - статья

VL - 467

SP - 437

EP - 450

JO - Monthly Notices of the Royal Astronomical Society

JF - Monthly Notices of the Royal Astronomical Society

SN - 0035-8711

IS - 1

ER -