Photometry as a Proxy for Stellar Activity in Radial Velocity Analyses

Kosiarek, Molly R.; Crossfield, Ian J. M.

doi:10.3847/1538-3881/ab8d3a

Cited by 36 publications

(40 citation statements)

References 34 publications

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“…Another method is to use photometry to characterize the stellar activity and then subsequently fold the activity information into radial velocity fits (Haywood et al 2014). For the Sun, there is a connection between stellar activity information derived from photometry, activity indicators, and radial velocity data (Kosiarek & Crossfield 2020). Here we investigate how stellar activity manifests in the K2 light curve, the Calcium II H&K and H-alpha stellar lines, and our radial velocity data.…”

Section: Hd 106315 Imagingmentioning

confidence: 99%

Physical Parameters of the Multiplanet Systems HD 106315 and GJ 9827* †

Kosiarek

Berardo

Crossfield

et al. 2020

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HD 106315 and GJ 9827 are two bright, nearby stars that host multiple super-Earths and sub-Neptunes discovered by K2 that are well suited for atmospheric characterization. We refined the planets' ephemerides through Spitzer transits, enabling accurate transit prediction required for future atmospheric characterization through transmission spectroscopy. Through a multi-year high-cadence observing campaign with Keck/HIRES and Magellan/PFS, we improved the planets' mass measurements in anticipation of HST transmission spectroscopy. For GJ 9827, we modeled activity-induced radial velocity signals with a Gaussian process informed from the Calcium II H&K lines in order to more accurately model the effect of stellar noise on our data. We found planet masses of M b =4.87±0.37 M ⊕ , M c =1.92 ± 0.49 M ⊕ , and M d =3.42 ± 0.62 M ⊕ . For HD 106315, we found that such activity-radial velocity decorrelation was not effective due to the reduced presence of spots and speculate that this may extend to other hot stars as well (T eff > 6200 K). We found planet masses of M b =10.5 ± 3.1 M ⊕ and M c =12.0 ± 3.8 M ⊕ . We investigated all of the planets' compositions through comparing their masses and radii to a range of interior models. GJ 9827 b and GJ 9827 c are both consistent with an Earth-like rocky composition, GJ 9827 d and HD 106315 b both require additional volatiles and are consistent with moderate amounts of water or hydrogen/helium, and HD 106315 c is consistent with 10% hydrogen/helium by mass.

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Section: Hd 106315 Imagingmentioning

confidence: 99%

Physical Parameters of the Multiplanet Systems HD 106315 and GJ 9827* †

Kosiarek

Berardo

Crossfield

et al. 2020

Self Cite

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“…The correction of stellar activity in the RV time series, point (3), has also been widely studied (e.g. Haywood et al 2014;Grunblatt et al 2015;Davis et al 2017;Jones et al 2017;Dumusque 2018;Cretignier et al 2020a;Kosiarek & Crossfield 2020;Collier Cameron et al 2020). Only point (2), corresponding to a better extraction of the RV content of a spectra, has not been intensively studied in the last decade.…”

Section: Introductionmentioning

confidence: 99%

YARARA: Significant improvement in RV precision through post-processing of spectral time series

Cretignier

Dumusque

Hara

et al. 2021

A&A

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Aims. Even the most precise radial-velocity instruments gather high-resolution spectra that present systematic errors that a data reduction pipeline cannot identify and correct for efficiently by simply analysing a set of calibrations and a single science frame. In this paper we aim at improving the radial-velocity precision of HARPS measurements by 'cleaning' individual extracted spectra using the wealth of information contained in spectral time series. Methods. We developed YARARA, a post-processing pipeline designed to clean high-resolution spectra of instrumental systematics and atmospheric contamination. Spectra are corrected for: tellurics, interference patterns, detector stitching, ghosts, and fibre B contaminations, as well as more advanced spectral line-by-line corrections. YARARA uses principal component analysis on spectral time series with prior information to disentangle contaminations from real Doppler shifts. We applied YARARA to three systems, HD10700, HD215152, and HD10180, and compared our results to the standard HARPS data reduction software and the SERVAL post-processing pipeline.Results. We ran YARARA on the radial-velocity dataset of three stars intensively observed with HARPS: HD10700, HD215152, and HD10180. For HD10700, we show that YARARA enables us to obtain radial-velocity measurements that present an rms smaller than 1 m s −1 over the 13 years of the HARPS observations, which is 20% and 10% better than the HARPS data reduction software and the SERVAL post-processing pipeline, respectively. We also injected simulated planets into the data of HD10700 and demonstrated that YARARA does not alter pure Doppler-shifted signals. For HD215152, we demonstrated that the 1-year signal visible in the periodogram becomes marginal after processing with YARARA and that the signals of the known planets become more significant. Finally, for HD10180, the six known exoplanets are well recovered, although different orbital parameters and planetary masses are provided by the new reduced spectra. Conclusions. The post-processing correction of spectra using spectral time series allows the radial-velocity precision of HARPS data to be significantly improved and demonstrates that for the extremely quiet star HD10700 a radial-velocity rms better than 1 m/s can be reached over the 13 years of HARPS observations. Since the processing proposed in this paper does not absorb planetary signals, its application to intensively followed systems is promising and will certainly result in advances in the detections of the lightest exoplanets.

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“…Mass-radius relationships produced by our model (green, yellow and red thick lines) [2], compared to mass-radius relationships of planets with only condensed phases and no atmosphere (black, grey and light blue thin lines) [3,4]. A few planets of the solar system, the GJ-9827 system and the TOI-178 system are shown as well [5,6].…”

Section: Figurementioning

confidence: 99%

Modeling the structure of irradiated ocean planets - implications for mass-radius relationships

Aguichine

Mousis

Deleuil

et al. 2024

Preprint

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HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

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Photometry as a Proxy for Stellar Activity in Radial Velocity Analyses

Cited by 36 publications

References 34 publications

Physical Parameters of the Multiplanet Systems HD 106315 and GJ 9827* †

Physical Parameters of the Multiplanet Systems HD 106315 and GJ 9827* †

YARARA: Significant improvement in RV precision through post-processing of spectral time series

Modeling the structure of irradiated ocean planets - implications for mass-radius relationships

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