Performance of the Southern African Large Telescope (SALT) High Resolution Spectrograph (HRS)

Crause, Lisa A.; Sharples, R. M.; Bramall, David; Schmoll, J.; Clark, Paul; Younger, Eddy; Tyas, Luke; Ryan, Sean G.; Brink, Janus D.; Strydom, Ockert J.; Buckley, D.; Wilkinson, Martin; Crawford, S.; Depagne, É.

doi:10.1117/12.2055635

Cited by 78 publications

(33 citation statements)

References 2 publications

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“…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). Observations were taken in High Resolution (HR) mode, R ≃ 65 000, with an integration time of 158 s. The signal-to-noise ratio varied between about 100 and 150 in the central region of the spectrum, dependent on observing conditions.…”

Section: Spectroscopymentioning

confidence: 99%

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: Spectroscopymentioning

confidence: 99%

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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“…A spectroscopic survey of stars classified as helium-rich subdwarfs, especially He-sdB or sdOD using 8m class telescopes has been undertaken. This paper reports an observation of one such star obtained with the high-resolution spectrograph (HRS) on the Southern Africa Large Telescope (SALT) (Buckley et al 2006;Bramall et al 2010;Crause et al 2014) 2 OBSERVATIONS GALEX J184559.8−413827 (α2000 = 18…”

Section: Introductionmentioning

confidence: 99%

GALEX J184559.8−413827: a new extreme helium star identified using SALT★

Jeffery

2017

Monthly Notices of the Royal Astronomical Society

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A high-resolution spectrum of the helium-rich 'hot subdwarf' GALEX J184559.8−413827 ( J1845−4138) obtained with SALT HRS demonstrates it to be the first extreme helium (EHe) star to be discovered in nearly 40 years. A quantitative analysis demonstrates it to have an atmosphere described by T eff = 26 170 ± 750 K, log g/cm s −2 = 4.22 ± 0.10, and a surface chemistry characterised by CNO-processed helium, a 1% contamination of hydrogen (by number), and a metallicity 0.4 dex subsolar. Its distance and position are consistent with membership of the Galactic bulge. Its sharp absorption lines place strong constraints on both the rotation and microturbulent velocities. Spectroscopically, J1845−4138 closely resembles the pulsating EHe star V652 Her, generally considered to be the product of a double helium white dwarf merger evolving to become a helium-rich sdO star.

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“…We observed the optical counterpart of RX J0209.6-7427 with the Southern African Large Telescope (SALT; Buckley et al 2006) using the Robert Stobie Spectrograph (RSS; Burgh et al 2003;Kobulnicky et al 2003) and the High Resolution Spectrograph (HRS; Bramall et al 2010;Crause et al 2014). The observation performed with the RSS was obtained on 21 November 2019 with grating PG1800 (resolution ∼2.6 Å) and covers a wavelength range 6000 − 7250 Å.…”

Section: Saltmentioning

confidence: 99%

A major optical and X-ray outburst from the Magellanic Bridge source RX J0209.6–7427

Coe

Monageng

Bartlett

et al. 2020

Monthly Notices of the Royal Astronomical Society

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RX J0209.6-7427 is an X-ray source in the Magellanic Bridge that was first detected in 1993, but not seen again till 2019. It has been identified as a member of the Be/X-ray binary class, a category of objects that are well established as bright, often-unpredictable transients. Such systems are rarely known in the Bridge, possibly because they lie outside the area most commonly studied by X-ray telescopes. Whatever the reason for the sparse number of such systems in the Bridge, they can provide useful tools for trying to understand the result of the tidal dynamics of the two Magellanic Clouds. In this paper the nature of the object is explored with the help of new data obtained during the latest outburst. In particular, the first optical spectrum of the counterpart is presented to help classify the star, plus measurements of the Balmer emission lines over several years are used to investigate changes in the size and structure of the circumstellar disk.

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Performance of the Southern African Large Telescope (SALT) High Resolution Spectrograph (HRS)

Cited by 78 publications

References 2 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

GALEX J184559.8−413827: a new extreme helium star identified using SALT★

A major optical and X-ray outburst from the Magellanic Bridge source RX J0209.6–7427

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