A5043697423- Stellar, planetary, and galactic studies
- Astro and Planetary Science
- Astronomy and Astrophysical Research
- Astrophysics and Star Formation Studies
- Solar and Space Plasma Dynamics
- Astronomical and nuclear sciences
- Astronomical Observations and Instrumentation
- Gamma-ray bursts and supernovae
- Geophysics and Gravity Measurements
- Scientific Research and Discoveries
- Geophysics and Sensor Technology
- Nuclear physics research studies
- Advanced Frequency and Time Standards
- Space Exploration and Technology
- Spectroscopy and Chemometric Analyses
- Geology and Paleoclimatology Research
- Sparse and Compressive Sensing Techniques
- Gaussian Processes and Bayesian Inference
- History and Developments in Astronomy
- Classical Antiquity Studies
- Planetary Science and Exploration
- Advanced X-ray and CT Imaging
- Space Science and Extraterrestrial Life
- Geomagnetism and Paleomagnetism Studies
- Advanced MRI Techniques and Applications
Heidelberg Institute for Theoretical Studies
2022-2024
New York University Abu Dhabi
2016-2023
New York University
2016-2020
Centre for Astrophysics of the University of Porto
2008-2019
Goddard Institute for Space Studies
2018
Space Science Institute
2016
Universidade do Porto
2008-2015
Institute of Astrophysics and Space Sciences
2015
Aarhus University
2008-2011
Observatoire Midi-Pyrénées
2004-2005
We combine results from interferometry, asteroseismology and spectroscopy to determine accurate fundamental parameters of 23 bright solar-type stars, spectral type F5 K2 luminosity classes III–V. For some stars we can use direct techniques the mass, radius, effective temperature, compare with indirect methods that rely on photometric calibrations or spectroscopic analyses. asteroseismic information available in literature infer an mass accuracy 4–15 per cent. From radius 3 find evidence...
In this letter we present the discovery of a very light planetary companion to star μ Ara (HD 160691). The planet orbits its host once every 9.5 days, and induces sinusoidal radial velocity signal with semi-amplitude 4.1 m s-1, smallest Doppler amplitude detected so far. These values imply mass 14 (Earth-masses). This detection represents slightly smaller than that Uranus, "ice giant" in our Solar System. Whether can be considered an ice giant or super-earth is discussed context...
The primary science goal of the Kepler Mission is to provide a census exoplanets in solar neighborhood, including identification and characterization habitable Earth-like planets. asteroseismic capabilities mission are being used determine precise radii ages for target stars from their solar-like oscillations. Chaplin et al. (2010) published observations three bright G-type stars, which were monitored during first 33.5 days operations. One these subgiant KIC 11026764, exhibits characteristic...
We present preliminary asteroseismic results from Kepler on three G-type stars. The observations, made at one-minute cadence during the first 33.5d of science operations, reveal high signal-to-noise solar-like oscillation spectra in all stars: About 20 modes may be clearly distinguished each star. discuss appearance spectra, use frequencies and frequency separations to provide radii, masses ages stars, comment light these prospects for inference other solar-type stars that will observe.
The star HD 52265 is a G0V metal-rich exoplanet-host observed in the seismology field of CoRoT space telescope from November 2008 to March 2009. satellite collected 117 days high-precision photometric data on this star, showing that it presents solar-like oscillations. was also spectroscopy with Narval spectrograph at same epoch. We characterise using both spectroscopic and seismic data. fundamental stellar parameters were derived semi-automatic software VWA, projected rotational velocity...
We study with unprecedented detail the chemical composition and stellar parameters of solar twin 18 Sco in a strictly differential sense relative to Sun. Our is mainly based on high-resolution (R ∼ 110,000), high signal-to-noise ratio (800–1,000) Very Large Telescope UVES spectra, which allow us achieve precision about 0.005 dex abundances. The effective temperature surface gravity are Teff = 5823 ± 6 K log g 4.45 0.02 dex, i.e., 46 hotter than Sun 0.01 higher. Its metallicity [Fe/H] 0.054...
We present the discovery of TOI-197.01, first transiting planet identified by Transiting Exoplanet Survey Satellite (TESS) for which asteroseismology host star is possible. TOI-197 (HIP116158) a bright (V=8.2 mag), spectroscopically classified subgiant oscillates with an average frequency about 430 muHz and displays clear signature mixed modes. The oscillation amplitude confirms that redder TESS bandpass compared to Kepler has small effect on oscillations, supporting expected yield thousands...
While Jupiter's massive gas envelope consists mainly of hydrogen and helium, the key to understanding formation evolution lies in distribution remaining (heavy) elements. Before Juno mission, lack high-precision gravity harmonics precluded use statistical analyses a robust determination heavy-elements envelope. In this paper, we assemble most comprehensive diverse collection Jupiter interior models date it study heavy elements planet's We apply Bayesian approach our model calculations,...
The Juno mission has provided measurements of Jupiter s gravity field with an outstanding level accuracy, leading to better constraints on the interior planet. Improving our knowledge internal structure is key understanding its formation and evolution but also important in framework exoplanet exploration. In this study, we investigated differences between state-of-the-art equations state their impact properties models. Accounting for uncertainty hydrogen helium equation state, assessed span...
établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics privés.
We present the first detailed chemical abundance analysis of old 8.2 Gyr solar twin, HIP 102152. derive differential abundances 21 elements relative to Sun with precisions as high 0.004 dex ($\lesssim$1%), using ultra high-resolution (R = 110,000), S/N UVES spectra obtained on 8.2-m Very Large Telescope. Our determined metallicity 102152 is [Fe/H] -0.013 $\pm$ 0.004. The atmospheric parameters star were be 54 K cooler than Sun, 0.09 lower in surface gravity, and a microturbulence identical...
The growing interest in solar twins is motivated by the possibility of comparing them directly to Sun. To carry on this kind analysis, we need know their physical characteristics with precision. Our first objective use asteroseismology and interferometry brightest them: 18 Sco. We observed star during 12 nights HARPS for seismology used PAVO beam-combiner at CHARA interferometry. An average large frequency separation 134.4 ± 0.3 μHz angular linear radiuses 0.6759 0.0062 mas 1.010 0.009 R⊙...
Rotation is thought to drive cyclic magnetic activity in the Sun and Sun-like stars. Stellar dynamos, however, are poorly understood owing scarcity of observations rotation fields Here, inferences drawn on internal a distant star by studying its global modes oscillation. We report asteroseismic constraints imposed rate inclination spin axis HD 52265, principal target observed CoRoT satellite that known host planetary companion. These seismic remarkably consistent with an independent...
The Kepler space telescope yielded unprecedented data for the study of solar-like oscillations in other stars. large samples multi-year observations posed an enormous analysis challenge that has only recently been surmounted. Asteroseismic modeling become more sophisticated over time, with better methods gradually developing alongside extended and improved techniques. We apply latest version Modeling Portal (AMP) to full-length sets 57 stars Sun, comprising planetary hosts, binaries,...
We present HARPS spectroscopy of μ Arae (HD 160691) performed for studying the origin metallicity excess in this planet-hosting stars. The asteroseismologic campaign led to previously reported discovery a 14 earth mass planetary companion (Santos et al. 2004b, A&A, 426, L19). analysis reinforces interpretation by excluding other possible processes explaining observed Doppler variation and leads identification up 43 p-mode oscillations with l = 0–3, frequencies range 1.3–2.5 mHz amplitudes...
We have analyzed data from a multi-site campaign to observe oscillations in the F5 star Procyon. The consist of high-precision velocities that we obtained over more than three weeks with eleven telescopes. A new method for adjusting weights allows us suppress sidelobes power spectrum. Stacking spectrum so-called echelle diagram reveals two clear ridges identify even and odd values angular degree (l=0 2, l=1 3, respectively). interpret strong, narrow peak at 446 muHz lies close ridge as mode...
We analyze the non-standard mixing history of solar twins HIP 55459, 79672, 56948, 73815, and 100963, to determine as precisely possible their mass age. computed a grid evolutionary models with at several metallicities Toulouse-Geneva code for range stellar masses assuming an error bar +-50K in Teff. choose model that reproduces accurately observed low lithium abundances twins. Our best-fit each twin provides age solution constrained by Li content Teff determination. 56948 is most likely...
The differentially rotating outer layers of stars are thought to play a role in driving their magnetic activity, but the underlying mechanisms that generate and sustain differential rotation poorly understood. We report measurement latitudinal convection zones 40 Sun-like using asteroseismology. For most significant detections, stars' equators rotate approximately twice as fast mid-latitudes. shear inferred from asteroseismology is much larger than predictions numerical simulations.
High-quality astrometric, spectroscopic, interferometric and, importantly, asteroseismic observations are available for α Cen A, which is the closest binary star system to earth. Taking all these constraints into account, we study internal structure of by means theoretical modelling. Using Aarhus STellar Evolution Code (astec) and tools Computational Bayesian Statistics, in particular a Markov chain Monte Carlo algorithm, perform statistical inferences physical characteristics star. We find...
Context.Asteroseismology provides a unique tool for studying stellar interiors. Recently p modes have been detected on the bright solar-like star α Cen A thanks to high-precision radial-velocity measurements. However, better characterisation of these is clearly needed constrain theoretical models.
The evolved main-sequence Sun-like stars KIC 10273246 (F-type) and 10920273 (G-type) were observed with the NASA Kepler satellite for approximately ten months a duty cycle in excess of 90%. Such continuous long observations are unprecedented solar-type other than Sun. We aimed mainly at extracting estimates p-mode frequencies - as well individual mode parameters from power spectra light curves both stars, thus providing scope full seismic characterization. corrected instrumental effects...
Determining the physical characteristics of a star is an inverse problem consisting estimating parameters models for stellar structure and evolution, knowing certain observable quantities. We use Bayesian approach to solve this α Cen A, which allows us incorporate prior information on be estimated, in order better constrain problem. Our strategy based Markov chain Monte Carlo (MCMC) algorithm estimate posterior probability densities parameters: mass, age, initial chemical composition, etc....
A star is discovered to be the roundest natural object ever measured.
Asteroseismology has become a powerful tool to study the internal rotation of stars, and its allows constrain AM transport processes better understand their physical nature. In this context, we compared rates predicted by asteroseismology starspots measurements for four main-sequence stars from Kepler LEGACY sample, considering different prescriptions, investigated if some these prescriptions could be ruled out. We decoupled modelling structure rotational profile, respectively obtained an...