205 citations · 720 across the 22 of their papers we have counts for
11 papers · 1 filter
The Fe I 4377 Å Line as a Solar Faculae Indicator: Insights from Spectral Ratio Analysis
Katlyn L. Hobbs, Christopher A. Watson, Jean C. Costes +21
Faculae are a dominant source of stellar activity noise in radial velocity measurements, yet their low contrast and broad surface distribution make them difficult to track in disc-…
Spectral Ratio Analysis: probing of a new suite of stellar activity indicators as a tool for astrophysical noise mitigation
Jean C. Costes, Christopher A. Watson, Ernst de Mooij +6
Stellar activity is the main barrier to detecting and/or confirming low-mass/long-period (and Earth-analogue) planets using radial-velocity (RV) measurements. Searching for reliabl…
A Decade of Solar High-Fidelity Spectroscopy and Precise Radial Velocities from HARPS-N
X. Dumusque, K. Al Moulla, M. Cretignier +53
We recently released 10 years of HARPS-N solar telescope and the goal of this manuscript is to present the different optimisations made to the data reduction, to describe data cura…
NGTS-EB-7, an eccentric, long-period, low-mass eclipsing binary
Toby Rodel, Christopher. A. Watson, Solène Ulmer-Moll +35
Despite being the most common types of stars in the Galaxy, the physical properties of late M dwarfs are often poorly constrained. A trend of radius inflation compared to evolution…
Periodic stellar variability from almost a million NGTS light curves
Joshua T. Briegal, Edward Gillen, Didier Queloz +25
We analyse 829,481 stars from the Next Generation Transit Survey (NGTS) to extract variability periods. We utilise a generalisation of the autocorrelation function (the G-ACF), whi…
Long-term stellar activity variations and their effect on radial-velocity measurements
Jean C. Costes, Christopher A. Watson, Ernst de Mooij +8
Long-term stellar activity variations can affect the detectability of long-period and Earth-analogue extrasolar planets. We have, for 54 stars, analysed the long-term trend of five…
The spectral impact of magnetic activity on disk-integrated HARPS-N solar observations: exploring new activity indicators
A. P. G. Thompson, C. A. Watson, R. D. Haywood +21
Stellar activity is the major roadblock on the path to finding true Earth-analogue planets with the Doppler technique. Thus, identifying new indicators that better trace magnetic a…
Temporal evolution and correlations of optical activity indicators measured in Sun-as-a-star observations
J. Maldonado, D. F. Phillips, X. Dumusque +29
(Abridged) We perform a detailed study of the main optical activity indicators (Ca II H & K, Balmer lines, Na I D D, and He I D) measured for the Sun…
NGTS-7Ab: An ultra-short period brown dwarf transiting a tidally-locked and active M dwarf
James A. G. Jackman, Peter J. Wheatley, Dan Bayliss +36
We present the discovery of NGTS-7Ab, a high mass brown dwarf transiting an M dwarf with a period of 16.2 hours, discovered as part of the Next Generation Transit Survey (NGTS). Th…
Three years of Sun-as-a-star radial-velocity observations on the approach to solar minimum
A. Collier Cameron, A. Mortier, D. Phillips +33
The time-variable velocity fields of solar-type stars limit the precision of radial-velocity determinations of their planets' masses, obstructing detection of Earth twins. Since 20…
HARPS-N Solar Radial-Velocity Variations Are Dominated By Large, Bright Magnetic Regions
T. W. Milbourne, R. D. Haywood, D. F. Phillips +37
State of the art radial-velocity (RV) exoplanet searches are currently limited by RV signals arising from stellar magnetic activity. We analyze solar observations acquired over a 3…