Optical observations on milli-, micro-, and nanosecond timescales

Dravins, Dainis; Lindegren, L.; Mezey, E.

doi:10.1007/3-540-60057-4_259

Cited by 4 publications

(5 citation statements)

References 1 publication

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“…We did not use the in-transit spectra in order to avoid the Doppler shadow affecting our result. We also computed the v sin i using the Fourier transform method (Smith & Gray 1976;Dravins et al 1990). Because of the fast rotation of KELT-20, we were able to use the first three zero positions of the Fourier transform of all our mean line profiles to derive the projected rotational velocity.…”

Section: Mean Line Profilesmentioning

confidence: 99%

The GAPS programme at TNG

Rainer

Borsa

Pino

et al. 2021

A&A

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Context. Transiting ultra-hot Jupiters are ideal candidates for studying the exoplanet atmospheres and their dynamics, particularly by means of high-resolution spectra with high signal-to-noise ratios. One such object is KELT-20b. It orbits the fast-rotating A2-type star KELT-20. Many atomic species have been found in its atmosphere, with blueshifted signals that indicate a day- to night-side wind. Aims. We observe the atmospheric Rossiter-McLaughlin effect in the ultra-hot Jupiter KELT-20b and study any variation of the atmospheric signal during the transit. For this purpose, we analysed five nights of HARPS-N spectra covering five transits of KELT-20b. Methods. We computed the mean line profiles of the spectra with a least-squares deconvolution using a stellar mask obtained from the Vienna Atomic Line Database (Teff = 10 000 K, log g = 4.3), and then we extracted the stellar radial velocities by fitting them with a rotational broadening profile in order to obtain the radial velocity time-series. We used the mean line profile residuals tomography to analyse the planetary atmospheric signal and its variations. We also used the cross-correlation method to study a previously reported double-peak feature in the FeI planetary signal. Results. We observed both the classical and the atmospheric Rossiter-McLaughlin effect in the radial velocity time-series. The latter gave us an estimate of the radius of the planetary atmosphere that correlates with the stellar mask used in our work (Rp+atmo∕Rp = 1.13 ± 0.02). We isolated the planetary atmospheric trace in the tomography, and we found radial velocity variations of the planetary atmospheric signal during transit with an overall blueshift of ≈10 km s−1, along with small variations in the signal depth, and less significant, in the full width at half maximum (FWHM). We also find a possible variation in the structure and position of the FeI signal in different transits. Conclusions. We confirm the previously detected blueshift of the atmospheric signal during the transit. The FWHM variations of the atmospheric signal, if confirmed, may be caused by more turbulent condition at the beginning of the transit, by a variable contribution of the elements present in the stellar mask to the overall planetary atmospheric signal, or by iron condensation. The FeI signal show indications of variability from one transit to the next.

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Section: Mean Line Profilesmentioning

confidence: 99%

The GAPS programme at TNG

Rainer

Borsa

Pino

et al. 2021

A&A

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“…Though we have measured wavelengths on an absolute scale, and we will so present them, the problem of systematic errors in the absolute wavelength and the discussion of laboratory standards requires a separate discussion which will be the subject of another paper. Forbes (1961) published a history of the solar redshift problem up to 1962. The more recent work on line asymmetries and wavelength shifts has been critically reviewed by Dravins (1982) and again by Dravins et al (1981).…”

Section: Introductionmentioning

confidence: 99%

“…Forbes (1961) published a history of the solar redshift problem up to 1962. The more recent work on line asymmetries and wavelength shifts has been critically reviewed by Dravins (1982) and again by Dravins et al (1981). Andersen (1984) selected Fe 1 5576, a g = 0 line for study.…”

Section: Introductionmentioning

confidence: 99%

The center-to-limb wavelength shift of a number of Fraunhofer lines

Lopresto

Pierce

1985

Sol Phys

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“…However, we find that quite small revisions to the adopted continuum normalization can introduce significant changes to the transform (cf. Dravins et al 1990). We label our initial, 'by eye', continuum as 'c0' (Fig.…”

Section: B3 Ad Hoc Characterization: An Empirical Limit On Differenti...mentioning

confidence: 99%

A study of the rapid rotator $ζ$ Aql: differential surface rotation?

Howarth¹,

Bailey²,

Cotton³

et al. 2023

Preprint

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We report new, extremely precise, photopolarimetry of the rapidly-rotating A0 main-sequence star ζ Aql, covering the wavelength range ∼400-900nm, which reveals a rotationally-induced signal. We model the polarimetry, together with the flux distribution and line profiles, in the framework of Roche geometry with ω-model gravity darkening, to establish the stellar parameters. An additional constraint is provided by TESS photometry, which shows variability with a period, P phot , of 11.1 hr. Modelling based on solid-body surface rotation gives rotation periods, P rot , that are in only marginal agreement with this value. We compute new ester stellar-structure models to predict horizontal surface velocity fields, which depart from solid-body rotation at only the ∼2% level (consistent with a reasonably strong empirical upper limit on differential rotation derived from the line-profile analysis). These models bring the equatorial rotation period, P rot(e) , into agreement with P phot , without requiring any 'fine tuning' (for the Gaia parallax). We confirm that surface abundances are significantly subsolar ([M/H] −0.5). The star's basic parameters are established with reasonably good precision:• , and ω e /ω c = 0.95 ± 0.02. Comparison with single-star, solar-abundance stellar-evolution models incorporating rotational effects shows excellent agreement (but somewhat poorer agreement for models at [M/H] −0.4).

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Optical observations on milli-, micro-, and nanosecond timescales

Cited by 4 publications

References 1 publication

The GAPS programme at TNG

The GAPS programme at TNG

The center-to-limb wavelength shift of a number of Fraunhofer lines

A study of the rapid rotator $ζ$ Aql: differential surface rotation?

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