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

Böhm, T.; Zima, W.; Catala, C.; Alécian, E.; Pollard, K. R.; Wright, D. E.

doi:10.1051/0004-6361/200811460

Cited by 15 publications

(17 citation statements)

References 32 publications

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“…A weighted combination of the nightly F2D spectra can be seen in Fig. 5 (see Böhm et al 2009, for details of the method) and our results confirm the presence of low-degree non-radial pulsations: a peak at the dominant frequency F 1 is clearly seen with an apparentm of between 2 and 4 indicating a degree of between 0 and 2. Moreover, as can be seen in Table 2.3 of Kennelly (1994) (or in simulations with available online-NRP simulators), the symmetric pattern of the dynamical residual profile as seen in Fig.…”

Section: Mode Identification With the Fourier 2d Methodssupporting

confidence: 77%

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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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Section: Mode Identification With the Fourier 2d Methodssupporting

confidence: 77%

“…Most of them have been studied in photometry, but only very few in spectroscopy (e.g. Böhm et al 2004Böhm et al , 2009). However, owing to cancellation effects, only modes of low degree are detected in photometry or radial velocity curves.…”

Section: Introductionmentioning

confidence: 99%

Spectroscopic monitoring of the Herbig Ae star HD 104237

Fumel

Boehm

2012

A&A

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“…Therefore, their asteroseismological properties allow constraints to be placed on various PMS physical parameters, such as luminosity, mass and effective temperature, as well as on the internal structure, which is different from that of more evolved stars of the same mass. Good examples of known PMS δ Scuti stars are the spectroscopic binary system RS Chamaeleontis (Böhm et al 2009), V351 Ori (Ripepi et al 2003) and IP Per (Ripepi et al 2006). However, the asteroseismological study of some of the δ Scuti PMS stars found here is still in progress and is deferred to another paper (Ripepi et al, in preparation).…”

Section: Introductionmentioning

confidence: 99%

Pre-main-sequence stars in the star-forming complex Sh 2-284

Cusano¹,

Ripepi²,

Alcalá³

et al. 2010

Monthly Notices of the Royal Astronomical Society

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Located at the Galactic anticentre, Sh 2-284 is an H ii region that harbours several young open clusters. Dolidze 25, a rare metal-poor (Z similar to 0.004) young cluster, is one of these. Given its association with Sh 2-284, it is reasonable to assume a low metallicity for the whole H ii region. Sh 2-284 is expected to host a significant population of pre-main-sequence (PMS) stars of both low and intermediate mass (Herbig Ae stars). We aim to characterize these stars by means of a spectroscopic and photometric survey conducted with VIMOS@VLT and complemented with additional optical and infrared observations. In this survey we selected and characterized 23 PMS objects. We derived the effective temperature, the spectral energy distribution and luminosity of these objects, and, using theoretical PMS evolutionary tracks with the appropriate metallicity, we estimated the mass and the age of the studied objects. We also estimated a distance of 4 kpc for Sh 2-284, using the spectroscopic parallax of three OB stars. From the age determination we concluded that triggered star formation is occurring in this region. Our results show that a significant fraction of the young stellar objects (YSOs) may have preserved their disc/envelopes, in contrast with what is found in other recent studies of low-metallicity star-forming regions in the Galaxy. Finally, among the 23 bona fide PMS stars, we identified eight stars that are good candidates to be pulsators of the delta Scuti type

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“…Still, they report 22.079 d −1 as the most prominent variation for the primary component. Böhm et al (2009) observed RS Cha for 14 nights with the high-resolution echelle spectrograph Hercules at the Mt John telescope in New Zealand. They report the first clear detection of pulsation frequencies, both for the primary and secondary component.…”

Section: Pulsationsmentioning

confidence: 99%

Tidally perturbed pulsations in the pre-main sequence δ Scuti binary RS Cha

Steindl

Zwintz

Bowman

2021

A&A

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Context. Stellar components in binaries are subject to tidal forces which influence asteroseismic properties. Tidally pertubed pulsations have been reported for different objects but none of these are in their pre-main sequence phase of evolution. This makes RS Cha, consisting of two δ Scuti stars and with pulsational characteristics influenced by tidal effects, the first such object observed. Aims. We aim to investigate the pulsational properties of the eclipsing binary RS Cha in terms of the theory of tidally perturbed pulsations. Methods. Based on photometric time series obtained from the TESS satellite, we performed binary modelling using PHOEBE to interpret the binary light curve and to allow the investigation of the pulsations of both components in RS Cha. We modelled the detrended light curve with the superposition of linear modes. The frequencies were then interpreted as self excited modes perturbed by tidal forces. Results. We find evidence for tidally perturbed modes, which enables the identification of pulsation modes. RS Cha mainly exhibits dipole modes, while one prominent l = 2 or l = 3 mode is also inferred. The latter verifies previous results from spectroscopic time series. Conclusion. This work shows that RS Cha is an ideal candidate to test the theory of tidally perturbed pulsations within the framework of asteroseismic modelling. The identification of multiple pulsation modes using this theory is unprecedented and will be a keystone in the future of pre-main sequence asteroseismology. However, amplitude modulation caused by the changing light ratio during the orbital phase in an eclipsing binary also plays a significant role, which can complicate mode identification.

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

Cited by 15 publications

References 32 publications

Spectroscopic monitoring of the Herbig Ae star HD 104237

Spectroscopic monitoring of the Herbig Ae star HD 104237

Pre-main-sequence stars in the star-forming complex Sh 2-284

Tidally perturbed pulsations in the pre-main sequence δ Scuti binary RS Cha

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