Azimuthal structures in the wind and chromosphere of
the Herbig Ae star AB Aurigae. 
Results from the MUSICOS
1992 campaign

Böhm, T.; Catala, C.; Donati, J.‐F.; Welty, Alan D.; Baudrand, J.; Butler, C. J.; Carter, B.; Collier-Cameron, A.; Czarny, J.; Foing, B. H.; Ghosh, K. K.; Hao, Jinxin; Houdebine, E. R.; Huang, Lei; Jiang, S. Y.; Neff, J. E.; Rees, D. E.; Semel, M.; Simon, Theodore; Talavera, A.; Zhai, D. S.; Zhao, Furong

doi:10.1051/aas:1996295

Cited by 22 publications

(4 citation statements)

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“…Asteroseismology represents a modern tool for studying the stellar interiors of the enigmatic group of pre-main sequence (PMS) stars of intermediate mass (∼ 2-8 M ⊙ ), so called Herbig Ae/Be stars (Herbig, 1960;Strom et al, 1972;Finkenzeller & Mundt, 1984;Finkenzeller & Jankovics, 1984). Since their first systematic classification in 1960 (Herbig, 1960) this group of young stars has been extensively studied, but one of the major questions remains unanswered: how can the intense stellar activity and strong stellar winds (Praderie et al, 1982;Catala & Kunasz, 1987;Böhm &Catala, 1995 andBöhm et al, 1996), as well as the many highly variable emission lines observed in the spectra of these stars be explained?…”

Section: Introductionmentioning

confidence: 99%

Discovery of non-radial pulsations in the spectroscopic binary Herbig Ae star RS Chamaeleontis

Böhm¹,

Zima

Catala

et al. 2009

A&A

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Context. To understand the origin of stellar activity in pre-main sequence Herbig Ae/Be stars and to get a deeper insight in the interior of these enigmatic stars, the pulsational instability strip of Palla and Marconi is investigated. In this article we present a first discovery of non radial pulsations in the Herbig Ae spectroscopic binary star RS Cha. Aims. The goal of the present work is to detect for the first time directly by spectrographic means non-radial pulsations in a Herbig Ae star and to identify the largest amplitude pulsation modes. Methods. The spectroscopic binary Herbig Ae star RS Cha was monitored in quasi-continuous observations during 14 observing nights (Jan 2006) at the 1m Mt John (New Zealand) telescope with the Hercules high-resolution echelle spectrograph. The cumulated exposure time on the star was 44 hrs, corresponding to 255 individual high-resolution echelle spectra with R = 45000. Least square deconvolved spectra (LSD) were obtained for each spectrum representing the effective photospheric absorption profile modified by pulsations. Difference spectra were calculated by subtracting rotationally broadened artificial profiles; these residual spectra were analysed and non-radial pulsations were detected. A subsequent analysis with two complementary methods, namely Fourier Parameter Fit (FPF) and Fourier 2D (F2D) has been performed and first constraints on the pulsation modes have been derived. Results. For the very first time we discovered by direct observational means using high resolution echelle spectroscopy non radial oscillations in a Herbig Ae star. In fact, both components of the spectroscopic binary are Herbig Ae stars and both show NRPs. The FPF method identified 2 modes for the primary component with (degree ℓ, azimuthal order m) couples ordered by decreasing probability: f 1 = 21.11 d −1 with (ℓ,m) = (11,11), (11,9) or (10,6) and f 2 = 30.38 d −1 with (ℓ,m) = (10,6) or (9,5). The F2D analysis indicates for f 1 a degree ℓ = 8-10. For the secondary component, the FPF method identified 3 modes with (ℓ,m) ordered by decreasing probability: f 1 = 12.81 d −1 with (ℓ,m) = (2,1) or (2,2), f 2b = 19.11 d −1 with (ℓ,m) = (13,5) or (10,5) and f 3 = 24.56 d −1 with (ℓ,m) = (6,3) or (6,5). The F2D analysis indicates for f 1 a degree ℓ = 2 or 3, but proposes a contradictory identification of f 2 as a radial pulsation (ℓ = 0).

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Section: Introductionmentioning

confidence: 99%

Discovery of non-radial pulsations in the spectroscopic binary Herbig Ae star RS Chamaeleontis

Böhm¹,

Zima

Catala

et al. 2009

A&A

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“…In the future, much attention must be paid to the suggestions made by Thomas [87] and the references therein concerning the properties of atmospheres of active stars having, in addition to the atmospheric structures modified by the rapid rotation, a more or less permanent supply of non-thermal energy by the sources of hydrodynamic and magnetic nature, to better understand the internal structure of these objects. Up to now, instead, few authors have studied the consequences produced by the deviations from the classical thermal structure of stellar atmospheres on the emitted spectra, e.g., [88][89][90][91][92][93][94][95][96].…”

Section: Disc-shaped Envelopes In Be Stars Just a Few Remindersmentioning

confidence: 99%

BCD Spectrophotometry and Rotation of Active B-Type Stars: Theory and Observations

Zorec

2023

Galaxies

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This review has two parts. The first one is devoted to the Barbier–Chalonge–Divan (BCD) spectrophotometric system, also known as the Paris spectral classification system. Although the BCD system has been applied and is still used for all stellar objects from O to F spectral types, the present account mainly concerns normal and ‘active’ B-type stars. The second part treats topics related to stellar rotation, considered one of the key phenomena determining the structure and evolution of stars. The first part is eminently observational. In contrast, the second part deals with observational aspects related to stellar rotation but also recalls some supporting or basic theoretical concepts that may help better understand the gains and shortcomings of today’s existent interpretation of stellar data.

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“…Short-term variability of many of these lines are observed and P Cygni profiles of Hα, Hβ, Mg II h and k lines present in the spectra of some of these stars indicate the presence of strong and structured stellar winds (see e.g. Praderie et al 1982Praderie et al , 1986Catala & Talavera 1984;Catala et al 1986a,b;Catala & Kunasz 1987;Catala 1988;Böhm & Catala 1995;Böhm et al 1996).…”

Section: Introductionmentioning

confidence: 99%

Spectroscopic monitoring of the Herbig Ae star HD 104237

Fumel

Boehm

2012

A&A

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Context. Herbig Ae/Be stars are intermediate-mass pre-main sequence (PMS) stars showing signs of intense activity and strong stellar winds, whose origin is not yet understood in the frame of current theoretical models of stellar evolution for young stars. In addition, the evolutionary tracks of the earlier Herbig Ae stars cross the theoretical PMS instability strip located roughly in the same area of the HR diagram as the δ Scuti variables. Many of these stars exhibit pulsations of δ Scuti type. Aims. Understanding the internal structure of pulsating Herbig Ae stars based on asteroseismic studies will help constraining the origin of their tremendous activity, winds, and variability. It is therefore necessary to investigate the location of the PMS instability strip and of its boundaries, and to extend the sample of observed and studied pulsating Herbig Ae stars. The aim of this work was to carry out a thorough analysis of the line profile variations of the prototype Herbig Ae star HD 104237 based on high-resolution spectroscopy and to redetermine precisely its fundamental parameters, which are the basic ingredients of a forthcoming asteroseismic modeling. Methods. HD 104237 is a pulsating Herbig Ae star with eight detected frequencies based on the analysis of radial velocity variations. In this article, we reinvestigated an extensive high-resolution quasi-continuous spectroscopic data set in order to search for very faint indications of non-radial pulsations in the line profile by working on dynamical spectra of equivalent photospheric (LSD) profiles of HD 104237. A 2D Fourier analysis (F2D) was performed of the entire profile and the temporal variation of the central depth of the line was studied with the time-series analysis tools Period04 and SigSpec. We present the results of these analysis including the mode identification corresponding to the detected dominant frequency, as well as a new determination of its fundamental stellar parameters.Results. The analysis of spectroscopic data set of April 22-25 obtained at SAAO in 1999 has confirmed the presence of multiple oscillation modes of low-degree in HD 104237 and led to the first direct detection of a non-radial pulsation mode in this star: the dominant mode F1 was identified by the Fourier 2D method having a degree value comprised between 1 and 2, the symmetry of the pattern variation indicating an azimuthal order of ±1. The detailed study of the fundamental stellar parameters has provided a T eff , log g, and iron abundance of 8550 ± 150 K, 3.9 ± 0.3, and −4.38 ± 0.19 (i.e. [Fe/H] = +0.16 ± 0.19 ), respectively.

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Azimuthal structures in the wind and chromosphere of the Herbig Ae star AB Aurigae. Results from the MUSICOS 1992 campaign

Cited by 22 publications

References 14 publications

Discovery of non-radial pulsations in the spectroscopic binary Herbig Ae star RS Chamaeleontis

Discovery of non-radial pulsations in the spectroscopic binary Herbig Ae star RS Chamaeleontis

BCD Spectrophotometry and Rotation of Active B-Type Stars: Theory and Observations

Spectroscopic monitoring of the Herbig Ae star HD 104237

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