Inversion of stellar fundamental parameters from ESPaDOnS and Narval high-resolution spectra

Paletou, F.; Böhm, T.; Watson, Victor; Trouilhet, J.-F.

doi:10.1051/0004-6361/201424741

Cited by 27 publications

(43 citation statements)

References 28 publications

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“…Because the candidate is exceptionally bright, and thus amenable to future characterization, we investigated the signal more closely than others, as explained below. The star has been characterized by many groups over the years (e.g., Valenti & Fischer 2005;Paletou et al 2015). It lies at a distance of 35.296±0.052pc (Gaia Collaboration et al 2018) and its parameters are T eff =6120±50 K, R * =1.15±0.04 R e , M * =1.26±0.19 M e (Valenti & Fischer 2005), in good agreement with our derived values from Gaia DR2 and isochrones.…”

supporting

confidence: 86%

Planetary Candidates from K2 Campaign 16

Crossfield

Schlieder

et al. 2018

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Given that Campaign 16 of the K2 mission is one of just two K2 campaigns observed so far in "forward-facing" mode, which enables immediate follow-up observations from the ground, we present a catalog of interesting targets identified through photometry alone. Our catalog includes 30 high-quality planet candidates (showing no signs of being non-planetary in nature), 48 more ambiguous events that may be either planets or false positives, 164 eclipsing binaries, and 231 other regularly periodic variable sources. We have released light curves for all targets in C16 and have also released system parameters and transit vetting plots for all interesting candidates identified in this paper. Of particular interest is a candidate planet orbiting the bright F dwarf HD73344 (V=6.9, K=5.6) with an orbital period of 15 days. If confirmed, this object would correspond to a 2.56±0.18 R ⊕ planet and would likely be a favorable target for radial velocity characterization. This paper is intended as a rapid release of planet candidates, eclipsing binaries, and other interesting periodic variables to maximize the scientific yield of this campaign, and as a test run for the upcoming TESS mission, whose frequent data releases call for similarly rapid candidate identification and efficient follow up.

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confidence: 86%

Planetary Candidates from K2 Campaign 16

Crossfield

Schlieder

et al. 2018

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“…According to Kenyon & Hartmann (1995), this range of colors is centered on (R-I) c =0.75, i.e., the spectral type dK7. However, when we compiled and derived effective temperatures with the PCA-based inversion method (see Paletou et al 2015a and Section 3) for this sample of late-K dwarfs, we found on average higher temperatures than what would be expected from the (R-I) C -T eff tabulation of Kenyon & Hartmann (1995). We give the stellar parameters and spectral types of our late-K dwarf sample in Table 1.…”

Section: Selection Of a Sample Of Late-k Dwarfsmentioning

confidence: 84%

“…In the latter paper, stellar spectra of FGK stars were inverted using a so-called "learning database" made from the Elodie stellar spectra library (see Prugniel et al 2007): the "learning" occurs by using observed spectra for which fundamental parameters had already been evaluated. We note that the spectra considered in Paletou et al (2015a) had typical spectral resolutions  of 50,000 and 65,000: these are significantly lower than the resolution of the HARPS and SOPHIE data that will be analyzed in the present paper.…”

Section: Pca-based Inversion Of Stellar Fundamental Parameters For Lamentioning

confidence: 88%

“…HARPS and SOPHIE spectra were inverted using the PCA method introduced for stellar fundamental parameters by Paletou et al (2015a). In the latter paper, stellar spectra of FGK stars were inverted using a so-called "learning database" made from the Elodie stellar spectra library (see Prugniel et al 2007): the "learning" occurs by using observed spectra for which fundamental parameters had already been evaluated.…”

Section: Pca-based Inversion Of Stellar Fundamental Parameters For Lamentioning

confidence: 99%

“…Here we use two different approaches to determine these parameters in samples of late-K and M dwarfs. In the first approach, we use the principal component analysis (PCA)-based inversion technique of Paletou et al (2015a) by applying it to the Na I resonance doublet in our K dwarf sample (105 stars). For this sample of K dwarfs, we also compiled all published values of T eff in the literature and further derived new values of T eff based on measurements of the (R-I) C color: our conversion from (R-I) C to T eff uses the extensive calibration of Kenyon & Hartmann (1995).…”

Section: Introductionmentioning

confidence: 99%

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ROTATION–ACTIVITY CORRELATIONS IN K AND M DWARFS. I. STELLAR PARAMETERS AND COMPILATIONS OF v sin i AND P/sin i FOR A LARGE SAMPLE OF LATE-K AND M DWARFS*

Houdebine

Mullan

Paletou

et al. 2016

ApJ

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The reliable determination of rotation-activity correlations (RACs) depends on precise measurements of the following stellar parameters: T eff , parallax, radius, metallicity, and rotational speed vsini. In this paper, our goal is to focus on the determination of these parameters for a sample of K and M dwarfs. In a future paper (Paper II), we will combine our rotational data with activity data in order to construct RACs. Here, we report on a determination of effective temperatures based on the (R-I) C color from the calibrations of Mann et al. and Kenyon & Hartmann for four samples of late-K, dM2, dM3, and dM4 stars. We also determine stellar parameters (T eff , log(g), and [M/H]) using the principal component analysis-based inversion technique for a sample of 105 late-K dwarfs. We compile all effective temperatures from the literature for this sample. We determine empirical radius-[M/H] correlations in our stellar samples. This allows us to propose new effective temperatures, stellar radii, and metallicities for a large sample of 612 late-K and M dwarfs. Our mean radii agree well with those of Boyajian et al. We analyze HARPS and SOPHIE spectra of 105 late-K dwarfs, and we have detected vsini in 92 stars. In combination with our previous vsini measurements in M and K dwarfs, we now derive P/sin i measures for a sample of 418 K and M dwarfs. We investigate the distributions of P/sin i, and we show that they are different from one spectral subtype to another at a 99.9% confidence level.

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Inversion of the radiative transfer equation for polarized light

Iniesta

Cobo

2016

Living Rev. Sol. Phys.

120

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Since the early 1970s, inversion techniques have become the most useful tool for inferring the magnetic, dynamic, and thermodynamic properties of the solar atmosphere. The intrinsic model dependence makes it necessary to formulate specific means that include the physics in a properly quantitative way. The core of this physics lies in the radiative transfer equation (RTE), where the properties of the atmosphere are assumed to be known while the unknowns are the four Stokes profiles. The solution of the (differential) RTE is known as the direct or forward problem. From an observational point of view, the problem is rather the opposite: the data are made up of the observed Stokes profiles and the unknowns are the solar physical quantities. Inverting the RTE is therefore mandatory. Indeed, the formal solution of this equation can be considered an integral equation. The solution of such an integral equation is called the inverse problem. Inversion techniques are automated codes aimed at solving the inverse problem. The foundations of inversion techniques are critically revisited with an emphasis on making explicit the many assumptions underlying each of them. An incremental complexity procedure is advised for the implementation in practice. Coarse details of the profiles or coarsely sam- pled profiles should be reproduced first with simple model atmospheres (with, for example, a few physical quantities that are constant with optical depth). If the Stokes profiles are well sampled and differences between synthetic and observed ones are greater than the noise, then the inversion should proceed by using more complex models (that is, models where physical quantities vary with depth or, eventually, with more than one component). Significant im- provements are expected as well from the use of new inversion techniques that take the spatial degradation by the instruments into account.Comment: Invited review accepted for publication in Living Reviews in Solar Physics. 84 pages, 30 figure

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Inversion of stellar fundamental parameters from ESPaDOnS and Narval high-resolution spectra

Cited by 27 publications

References 28 publications

Planetary Candidates from K2 Campaign 16

Planetary Candidates from K2 Campaign 16

ROTATION–ACTIVITY CORRELATIONS IN K AND M DWARFS. I. STELLAR PARAMETERS AND COMPILATIONS OF v sin i AND P/sin i FOR A LARGE SAMPLE OF LATE-K AND M DWARFS*

Inversion of the radiative transfer equation for polarized light

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