Adrien Coffinet

Adrien Coffinet
University of Geneva | UNIGE · Department of Astronomy

Grenoble INP Phelma's Engineer Diploma (= Master)

About

30
Publications
8,615
Reads
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608
Citations
Introduction
I am currently a Ph.D. student working in the exoplanet group of the Observatory of Geneva.
Additional affiliations
October 2013 - present
University of Geneva
Position
  • PhD Student
March 2013 - September 2013
University of Geneva
Position
  • Intern
May 2012 - August 2012
National Optical Astronomy Observatory
Position
  • Intern
Education
September 2010 - June 2013
Ecole de Physique, Electronique et Matériaux (INP de Grenoble - PHELMA)
Field of study
  • Physics and nanosciences > Astrophysics, Plasmas and Planets

Publications

Publications (30)
Article
We present confirmation of the planetary nature of PH-2b, as well as the first mass estimates for the two planets in the Kepler-103 system. PH-2b and Kepler-103c are both long-period and transiting, a sparsely populated category of exoplanets. We use Kepler light-curve data to estimate a radius, and then use HARPS-N radial velocities to determine t...
Preprint
We present confirmation of the planetary nature of PH-2b, as well as the first mass estimates for the two planets in the Kepler-103 system. PH-2b and Kepler-103c are both long-period and transiting, a sparsely-populated category of exoplanet. We use {\it Kepler} light-curve data to estimate a radius, and then use HARPS-N radial velocities to determ...
Preprint
Although several thousands of exoplanets have now been detected and characterized, observational biases have led to a paucity of long-period, low-mass exoplanets with measured masses and a corresponding lag in our understanding of such planets. In this paper we report the mass estimation and characterization of the long-period exoplanet Kepler-538b...
Article
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 2015 July, we have been monitoring disc-integrated sunlight in daytime using a purpose-built solar telescope and fibre feed to the HARPS-N stellar radial-velocity spectrome...
Article
Context. The Transiting Exoplanet Survey Satellite (TESS) is revolutionising the search for planets orbiting bright and nearby stars. In sectors 3 and 4, TESS observed TOI-402 (TIC-120896927), a bright V = 9.1 K1 dwarf also known as HD 15337, and found two transiting signals with periods of 4.76 and 17.18 days and radii of 1.90 and 2.21 R⊕ , respec...
Preprint
Full-text available
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 2015 July we have been monitoring disc-integrated sunlight in daytime using a purpose-built solar telescope and fibre feed to the HARPS-N stellar radial-velocity spectromet...
Article
Super-Earths belong to a class of planet not found in the Solar system, but which appear common in the Galaxy. Given that some super-Earths are rocky, while others retain substantial atmospheres, their study can provide clues as to the formation of both rocky and gaseous planets, and - in particular - they can help to constrain the role of photoeva...
Article
Context. Doppler spectroscopy has been used in astronomy for more than 150 yr. In particular, it has permitted us to detect hundreds of exoplanets over the past 20 yr, and the goal today of detecting Earth-like planets requires a precision around 0.1 m s ⁻¹ or better. Doppler spectroscopy has also been and will be of major importance for other stud...
Preprint
Full-text available
TESS is revolutionising the search for planets orbiting bright and nearby stars. In sectors 3 and 4, TESS observed TOI-402 (TIC-120896927), a bright V=9.1 K1 dwarf also known as HD 15337, and found two transiting signals with period of 4.76 and 17.18 days and radius of 1.90 and 2.21\,\Rearth. This star was observed as part of the radial-velocity se...
Preprint
The study of Earth-mass extrasolar planets via the radial-velocity technique and the measurement of the potential cosmological variability of fundamental constants call for very-high-precision spectroscopy at the level of $\updelta\lambda/\lambda<10^{-9}$. Wavelength accuracy is obtained by providing two fundamental ingredients: 1) an absolute and...
Article
Full-text available
The study of Earth-mass extrasolar planets via the radial-velocity technique and the measurement of the potential cosmological variability of fundamental constants call for very-high-precision spectroscopy at the level of $\updelta\lambda/\lambda<10^{-9}$. Wavelength accuracy is obtained by providing two fundamental ingredients: 1) an absolute and...
Article
K2-291 is a solar-type star with a radius of R ∗ = 0.899 ±0.034 R and mass of M ∗ = 0.934 ±0.038 M . From the K2 C13 data, we found one super-Earth planet (R p = 1.589 -0.072+0.095 R ⊕ ) transiting this star on a short period orbit (P = 2.225177 -6.8e-5+6.6e-5 days). We followed this system up with adaptive-optic imaging and spectroscopy to derive...
Article
Context. K2-36 is a K dwarf orbited by two small ( Rb = 1.43 ± 0.08 R⊕ and Rc = 3.2 ± 0.3 R⊕ ), close-in ( ab = 0.022 au and ac = 0.054 au) transiting planets discovered by the Kepler /K2 space observatory. They are representatives of two distinct families of small planets ( Rp < 4 R⊕ ) recently emerged from the analysis of Kepler data, with likely...
Preprint
K2-36 is a K dwarf orbited by two small ($R_{\rm b}=1.43\pm0.08$ $R_\oplus$ and $R_{\rm c}=3.2\pm0.3$ $R_\oplus$), close-in ($a_{\rm b}$=0.022 AU and $a_{\rm c}$=0.054 AU) transiting planets discovered by Kepler/K2. They are representatives of two families of small planets ($R_{\rm p}$<4 $R_\oplus$) recently emerged from the analysis of Kepler data...
Preprint
We investigated the discrepancy between planetary mass determination using the transit timing variations (TTVs) and radial velocities (RVs), by analysing the multi-planet system Kepler-9. Despite being the first system characterised with TTVs, there are several discrepant solutions in the literature, with those reporting lower planetary densities b...
Preprint
EPIC 247418783 is a solar-type star with a radius of R_star = 0.899 $\pm$ 0.034 R_sun and mass of M_star=0.934 $\pm$ 0.038 M_sun. From K2 C13 data, we found one super-Earth planet (R_p = 1.589+0.095-0.072 R_Earth) transiting this star on a short period orbit (P = 2.225177 +6.6e-5 -6.8e-5 days). We followed this system up with adaptive-optic imaging...
Article
PIC 247418783 is a solar-type star with a radius of R_★ = 0.899 ± 0.034 R_⊙ and mass of M_★=0.934 ± 0.038 M_⊙ . From K2 C13 data, we found one super-Earth planet (R_p = 1.589^(+0.095)_(-0.072) R_⊕) transiting this star on a short period orbit (P = 2.225177 ^(+6.6e-5)_ (-6.8e-5) days). We followed this system up with adaptive-optic imaging and spect...
Preprint
(abridged) Even if the HARPS spectrograph has been operational for more than 15 years and it provides among the most precise Doppler measurements, improvements are still possible. One known problem, for instance, is the non-fully regular block-stitching of the CCDs, which introduces, in some cases, one-year period parasitic signals in the measured...
Preprint
Full-text available
Super-Earths belong to a class of planet not found in the Solar System, but which appear common in the Galaxy. Given that some super-Earths are rocky, while others retain substantial atmospheres, their study can provide clues as to the formation of both rocky planets and gaseous planets, and - in particular - they can help to constrain the role of...
Article
Context. We present radial-velocity measurements of eight stars observed with the HARPS Echelle spectrograph mounted on the 3.6-m telescope in La Silla (ESO, Chile). Data span more than ten years and highlight the long-term stability of the instrument. Aims. We search for potential planets orbiting HD 20003, HD 20781, HD 21693, HD 31527, HD 45184,...
Article
We report the discovery of four super-Earth planets around HD 215152, with orbital periods of 5.76, 7.28, 10.86, and 25.2 d, and minimum masses of 1.8, 1.7, 2.8, and 2.9 M_Earth respectively. This discovery is based on 373 high-quality radial velocity measurements taken by HARPS over 13 years. Given the low masses of the planets, the signal-to-nois...
Article
Ultra-short period (USP) planets are a class of low mass planets with periods shorter than one day. Their origin is still unknown, with photo-evaporation of mini-Neptunes and in-situ formation being the most credited hypotheses. Formation scenarios differ radically in the predicted composition of USP planets, it is therefore extremely important to...
Article
We present radial-velocity measurement of eight stars observed with the HARPS Echelle spectrograph mounted on the 3.6-m telescope in La Silla (ESO, Chile). Data span more than ten years and highlight the long-term stability of the instrument. We search for potential planets orbiting HD20003, HD20781, HD21693, HD31527, HD45184, HD51608, HD134060 and...
Article
Full-text available
We present the analysis of the entire HARPS observations of three stars that host planetary systems: HD1461, HD40307, and HD204313. The data set spans eight years and contains more than 200 nightly averaged velocity measurements for each star. This means that it is sensitive to both long-period and low-mass planets and also to the effects induced b...
Conference Paper
Full-text available
Spectroscopy was the first technique that allowed the detection of an extrasolar planet around a main-sequence star (Mayor & Queloz, 1995). Today, it remains one of the most efficient way to discover these objects: in addition to the confirmation of the numerous short-period planets detected by transits, the radial-velocity technique allows to expl...
Conference Paper
Full-text available
Today spectroscopy remains one of the most efficient way to discover new exoplanets: in addition to the confirmation of the numerous short-period planets detected by transits, the radial-velocity technique allows to explore regions farther away from the stars, too far for planets to have a significant probability of transiting but also too close fo...

Questions

Question (1)
Question
Hello everybody,
The generic equation of an asymmetric Gaussian curve is :
y = k * exp[-{(x-x0)^2}/{2*sig^2}] * [1+erf({a*(x-x0)}/{sig*sqrt(2)})].
I need to know the coordinates ("x" and "y") of the top (assuming k>0) of such an asymmetric Gaussian curve, as a function of the asymmetry parameter "a". Does there exist an analytic function that gives this? At least, does there exist such a function for the more specific but also simpler "y = exp[-{x^2}/2] * [1+erf({a*x}/{sqrt(2)})]" (i.e. with k=1, sig=1, x0=0)? Then it would be easy to generalize for any k, sig and x0.
Thank you very much.

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