A radial-velocity survey of Ap stars with HARPS

Hartmann, Michael; Hatzes, A. P.

doi:10.1051/0004-6361/201425320

Cited by 14 publications

(15 citation statements)

References 33 publications

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“…Spectroscopic observations spanning 4-yr were obtained by Hartmann & Hatzes (2015) using the High-Accuracy Radialvelocity Planet Searcher (HARPS) spectrograph on the 3.6-m telescope at the European Southern Observatory (ESO). Their 48 spectra, obtained on 16 nights, revealed significant radial velocity (RV) variations which were successfully modelled as being caused by eccentric binary motion with P orb = 93 d .…”

Section: Hd 42659mentioning

confidence: 99%

“…Since HD 42659 is the only roAp star known to be in a spectroscopic binary system (Hartmann & Hatzes 2015), it provides us with the opportunity to test whether the binary companion affects the pulsations in the Ap star. To that end, we obtained 27 spectra with the High Resolution Spectrograph (HRS; Bramall et al 2010;Crause et al 2014) mounted on the Southern African Large Telescope (SALT; Buckley et al 2006).…”

Section: Spectroscopymentioning

confidence: 99%

“…We fitted the final RV measurements with the rvlin code of Wright & Howard (2009), and included the bootstrapping method for error analysis by Wang et al (2012). We provided initial estimates of the system parameters based on those presented by Hartmann & Hatzes (2015) and the mass estimate from Kochukhov & Bagnulo (2006). The results of the fitting process are shown in Table 6.…”

Section: Radial Velocity Measurementsmentioning

confidence: 99%

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HD 42659: the only known roAp star in a spectroscopic binary observed with B photometry, TESS, and SALT

Holdsworth

Saio

Kurtz

2019

Monthly Notices of the Royal Astronomical Society

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We present a multi-instrument analysis of the rapidly oscillating Ap (roAp) star HD 42659. We have obtained B photometric data for this star and use these data, in conjunction with TESS observations, to analyse the high-frequency pulsation in detail. We find a triplet which is split by the rotation frequency of the star (ν rot = 0.3756 d −1 ; P rot = 2.66 d) and present both distorted dipole and distorted quadrupole mode models. We show that the pulsation frequency, 150.9898 d −1 (P puls = 9.54 min) is greater than the acoustic cutoff frequency. We utilise 27 high-resolution (R ≃ 65 000), high signal-to-noise (∼ 120) spectra to provide new orbital parameters for this, the only known roAp star to be in a short period binary (P orb = 93.266 d). We find the system to be more eccentric than previously thought, with e = 0.317, and suggest the companion is a mid-F to early-K star. We find no significant trend in the average pulsation mode amplitude with time, as measured by TESS, implying that the companion does not have an affect on the pulsation in this roAp star. We suggest further photometric observations of this star, and further studies to find more roAp stars in close binaries to characterise how binarity may affect the detection of roAp pulsations.

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Section: Hd 42659mentioning

confidence: 99%

Section: Spectroscopymentioning

confidence: 99%

Section: Radial Velocity Measurementsmentioning

confidence: 99%

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HD 42659: the only known roAp star in a spectroscopic binary observed with B photometry, TESS, and SALT

Holdsworth

Saio

Kurtz

2019

Monthly Notices of the Royal Astronomical Society

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“…Furthermore, the pulsation mode is classified as a distorted quadrupole mode for both J1940 and HD 24355. Further observations for the third member HD 42659 (its binary nature was recently discovered by Hartmann & Hatzes 2015) are highly desirable; it would be interesting to see whether the mode can be also classified as a distorted quadrupole. The presence of the group consisting of highly supercritical single-mode roAp stars might hint that there is yet another excitation mechanism at work in roAp stars.…”

Section: Modelling the Amplitude And Phase Variationsmentioning

confidence: 99%

Whole Earth Telescope discovery of a strongly distorted quadrupole pulsation in the largest amplitude rapidly oscillating Ap star

Holdsworth

Kurtz

Saio

et al. 2017

Monthly Notices of the Royal Astronomical Society

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We present a new analysis of the rapidly oscillating Ap (roAp) star, 2MASS J19400781 − 4420093 (J1940; V = 13.1). The star was discovered using SuperWASP broadband photometry to have a frequency of 176.39 d −1 (2041.55 µHz; P = 8.2 min; Holdsworth et al. 2014a) and is shown here to have a peak-to-peak amplitude of 34 mmag. J1940 has been observed during three seasons at the South African Astronomical Observatory, and has been the target of a Whole Earth Telescope campaign. The observations reveal that J1940 pulsates in a distorted quadrupole mode with unusual pulsational phase variations. A higher signal-to-noise ratio spectrum has been obtained since J1940's first announcement, which allows us to classify the star as A7 Vp Eu(Cr). The observing campaigns presented here reveal no pulsations other than the initially detected frequency. We model the pulsation in J1940 and conclude that the pulsation is distorted by a magnetic field of strength 1.5 kG. A difference in the times of rotational maximum light and pulsation maximum suggests a significant offset between the spots and pulsation axis, as can be seen in roAp stars.

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“…AF stars with well-established masses above 1 M on the main sequence are generally rejected from RV surveys because their specific characteristics (fewer spectral lines and faster rotation) hinder classical RV measurements. A recent survey has targeted chemically peculiar Ap stars, which exhibit lower rotational velocities and more narrow spectral lines than typical AF MS dwarfs (Hartmann & Hatzes 2015).…”

Section: Introductionmentioning

confidence: 99%

Extrasolar planets and brown dwarfs around AF-type stars

Borgniet

Lagrange

Meunier

et al. 2019

A&A

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Context. The impact of stellar mass on the properties of giant planets is still not fully understood. Main-sequence (MS) stars more massive than the Sun remain relatively unexplored in radial velocity (RV) surveys, due to their characteristics which hinder classical RV measurements. Aims. Our aim is to characterize the close (up to ~2 au) giant planet (GP) and brown dwarf (BD) population around AF MS stars and compare this population to stars with different masses. Methods. We used the SOPHIE spectrograph located on the 1.93 m telescope at Observatoire de Haute-Provence to observe 125 northern, MS AF dwarfs. We used our dedicated SAFIR software to compute the RV and other spectroscopic observables. We characterized the detected substellar companions and computed the GP and BD occurrence rates combining the present SOPHIE survey and a similar HARPS survey. Results. We present new data on two known planetary systems around the F5-6V dwarfs HD 16232 and HD 113337. For the latter, we report an additional RV variation that might be induced by a second GP on a wider orbit. We also report the detection of 15 binaries or massive substellar companions with high-amplitude RV variations or long-term RV trends. Based on 225 targets observed with SOPHIE and/or HARPS, we constrain the BD frequency within 2–3 au around AF stars to be below 4% (1σ). For Jupiter-mass GPs within 2–3 au (periods ≤103 days), we find the occurrence rate to be 3.7−1+3% around AF stars with masses <1.5 M⊙, and to be ≤6% (1σ) around AF stars with masses >1.5 M⊙. For periods shorter than 10 days, we find the GP occurrence rate to be below 3 and 4.5% (1σ), respectively. Our results are compatible with the GP frequency reported around FGK dwarfs and are compatible with a possible increase in GP orbital periods with stellar mass as predicted by formation models.

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A radial-velocity survey of Ap stars with HARPS

Cited by 14 publications

References 33 publications

HD 42659: the only known roAp star in a spectroscopic binary observed with B photometry, TESS, and SALT

HD 42659: the only known roAp star in a spectroscopic binary observed with B photometry, TESS, and SALT

Whole Earth Telescope discovery of a strongly distorted quadrupole pulsation in the largest amplitude rapidly oscillating Ap star

Extrasolar planets and brown dwarfs around AF-type stars

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