A5029307424- Stellar, planetary, and galactic studies
- Astronomy and Astrophysical Research
- Astrophysics and Star Formation Studies
- Astro and Planetary Science
- Galaxies: Formation, Evolution, Phenomena
- Astronomical Observations and Instrumentation
- Radio Astronomy Observations and Technology
- Astrophysics and Cosmic Phenomena
- Adaptive optics and wavefront sensing
- Gamma-ray bursts and supernovae
- Solar and Space Plasma Dynamics
- Pulsars and Gravitational Waves Research
- Astrophysical Phenomena and Observations
- Calibration and Measurement Techniques
- Ionosphere and magnetosphere dynamics
- Atomic and Molecular Physics
- Planetary Science and Exploration
- Nuclear physics research studies
- Nuclear Physics and Applications
- Geophysics and Gravity Measurements
- Spectroscopy and Laser Applications
Physical Research Laboratory
2011-2024
University of Bologna
2021
Observatoire des Sciences de l’Univers Terre Homme Environnement Temps Astronomie
2012-2016
Centre National de la Recherche Scientifique
2012-2016
Laboratoire d’Astrophysique de Marseille
2015-2016
Aix-Marseille Université
2015-2016
Institut UTINAM
2011-2014
Interface (United States)
2010-2011
While giant extrasolar planets have been studied for more than two decades now, there are still some open questions such as their dominant formation and migration process, well atmospheric evolution in different stellar environments. In this paper, we study a sample of transiting exoplanets detected by the Kepler telescope with orbital periods up to 400 days. We first defined 129 giant-planet candidates that followed SOPHIE spectrograph (OHP, France) 6-year radial velocity campaign. This...
Despite their large number in the Galaxy, M dwarfs remain elusive objects and modeling of photospheres has long remained a challenge (molecular opacities, dust cloud formation). Our objectives are to validate BT-Settl model atmospheres, update dwarf T eff -spectral type relation, find atmospheric parameters stars our sample. We compare two samples optical spectra covering whole sequence with most recent synthetic use \c{hi}2 minimization technique determine Teff . The first sample consists...
K2-19 is the second multi-planetary system discovered with K2 observations. The composed of two Neptune size planets close to 3:2 mean-motion resonance. To better characterise we obtained additional transit observations K2-19b and five radial velocity These were combined data fitted simultaneously dynamics (photo-dynamical model) which increases precision time measurements. higher allows us detect chopping signal dynamic interaction that in turn permits uniquely system. Although reflex...
Present and future high-precision radial-velocity spectrometers dedicated to the discovery of low-mass planets orbiting dwarfs need focus on best selected stars make an efficient use telescope time. In framework preparation SPIRou Input Catalog, CoolSnap program aims at screening M in solar neighborhood against binarity, rapid rotation, activity, ... To optimize selection, present paper describes methods used compute effective temperature, metallicity, projected rotation velocity a large...
Context . Being the most numerous and oldest stars in galaxy, M dwarfs are objects of great interest for exoplanet searches. The presence molecules their atmosphere complicates our understanding atmospheric properties. But advances have recently been made modeling due to revision solar abundances. Aims We aim determine stellar parameters using high resolution spectra ( R ∼ 90 000) simultaneously visible near-infrared. broad wavelength coverage provide an unique opportunity understand onset...
We present the first deep low frequency radio observations of massive and highly disturbed galaxy cluster Abell 2744 using upgraded Giant Metrewave Radio Telescope (uGMRT). The is experiencing a very complex multiple merger hosts giant halo four relics. uGMRT observations, together with existing VLA Chandra allow us to study complexity physical mechanisms active in this system. Our new images reveal that central emission more extended toward frequencies. find integrated spectrum follows...
Context. M subdwarfs are metal poor and cool stars. They important probes of the old galactic populations. However, they remain elusive due to their low luminosity. Observational modeling efforts required fully understand physics investigate effects metallicity in atmospheres. Aims. We perform a detailed study sample determine stellar parameters constrain stat-of-the art atmospheric models. Methods. present UVES/VLT high resolution spectra three late-K 18 subdwarfs. Our atlas covers optical...
The K2 mission has recently begun to discover new and diverse planetary systems. In December 2014 Campaign 1 data from the was released, providing high-precision photometry for ~22000 objects over an 80 day timespan. We searched these with aim of detecting further important objects. Our search through two separate pipelines led independent discovery K2-19b \& c, a two-planet system Neptune sized (4.2 7.2 $R_\oplus$), orbiting K dwarf extremely close 3:2 mean motion resonance. planets each...
ABSTRACT In the present paper we report discovery of a new hot Jupiter, K2-29 b, first detected by Super-WASP observatory and then K2 space mission during its campaign 4. The planet has period 3.25 days, mass 0.73 ± 0.04 M ♃ , radius 1.19 0.02 R . host star is relatively bright ( V = 12.5) G7 dwarf with nearby K5V companion. Based on stellar rotation abundance lithium, find that system might be as young ~450 Myr. observation Rossiter–McLaughlin effect shows aligned respect to spin. Given...
We present new LOw-Frequency ARray observations of the massive merging galaxy cluster MACS J0717.5+3745, located at a redshift 0.5458. The hosts most powerful radio halo known to date. These observations, in combination with published uGMRT (300−850 MHz) and VLA (1−6.5 GHz) data, reveal that is more extended than previously thought, largest linear size ∼2.2 Mpc, making it one halos. shows steep spectrum ( α 144 MHz 1.5 GHz ∼ −1.4) steepening 5.5 −1.9) above GHz. find strong scattering...
Abstract We present deep and high-fidelity images of the merging galaxy cluster A2256 at low frequencies using upgraded Giant Metrewave Radio Telescope (uGMRT) LOw-Frequency ARray (LOFAR). This hosts one most prominent known relics with a remarkably spectacular network filamentary substructures. The new uGMRT (300–850 MHz) LOFAR (120–169 observations, combined archival Karl G. Jansky Very Large Array (VLA; 1–4 GHz) data, allowed us to carry out first spatially resolved spectral analysis...
We are carrying out a large ancillary program with the SDSS-III, using fiber-fed multi-object NIR APOGEE spectrograph, to obtain high-resolution H-band spectra of more than 1200 M dwarfs. These observations used measure spectroscopic rotational velocities, radial physical stellar parameters, and variability target stars. Here, we describe selection for this survey results from first year scientific based on that is publicly available in SDSS-III DR10 data release. As part paper present RVs...
We present the first detailed analysis of radio halo in merging galaxy cluster Abell 2256 using LOFAR, uGMRT, and VLA. These observations combined with archival X-ray data allowed us to study emission unprecedented detail. The integrated from entire is characterized by an ultra-steep spectrum, which can be described a power law $\alpha_{144 \rm MHz}^{1.5 GHz}=-1.63\pm0.03$, radial steepening outer regions. significantly underluminous according scaling relations between mass at 1.4 GHz but...
Radio relics are diffuse, extended synchrotron sources that originate from shock fronts generated during cluster mergers. The massive merging galaxy MACS J0717.5+3745 hosts one of the more complex known to date. We present upgraded Giant Metrewave Telescope band 3 (300−500 MHz) and 4 (550−850 observations. These new observations, combined with published VLA LOFAR HBA data, allow us carry out a detailed, high spatial resolution spectral analysis relic over broad range frequencies. integrated...
We review recent advancements in modeling the stellar to substellar transition. The revised molecular opacities, solar oxygen abundances and cloud models allow reproduce photometric spectroscopic properties of this transition a degree never achieved before, but problems remain important M-L characteristic effective temperature range characterizable exoplanets. discuss validity these classical models. also present new preliminary global Radiation HydroDynamical M dwarfs simulations.
We present wideband polarimetric observations, obtained with the Karl G. Jansky Very Large Array (VLA), of merging galaxy cluster MACS J0717.5+3745, which hosts one most complex known radio relic and halo systems. use both Rotation Measure Synthesis QU-fitting, find a reasonable agreement results these methods, in particular, when Faraday distribution is simple depolarization mild. The highly polarized over its entire length reaching fractional polarization ${>}30\%$ some regions. also...
M dwarfs are an important source of information when studying and probing the lower end Hertzsprung-Russell (HR) diagram, down to hydrogen-burning limit. Being most numerous oldest stars in galaxy, they carry fundamental on its chemical history. The presence molecules their atmospheres, along with various condensed species, complicates our understanding physical properties thus makes determination stellar parameters more challenging difficult. aim this study is perform a detailed...
Context. M-type subdwarfs are metal-poor low-mass stars and probe for the old populations in our Galaxy. Accurate knowledge of their atmospheric parameters especially composition is essential understanding chemical history Aims. The purpose this work to perform a detailed study M-subdwarf spectra covering full wavelength range from optical near-infrared. It allows do more analysis order determine stellar parameters, constrain models. will allow us further understand physical processes such...
We report the discovery of two hot-Jupiters K2-30b and K2-34b. The planets were detected transiting their main-sequence star with periods $\sim$ 4.099 2.996 days, in campaigns 4 5 extension Kepler mission, K2. Subsequent ground-based radial velocity follow-up SOPHIE, HARPS-N CAFE, established planetary nature objects. analyzed transit signal, spectral energy distributions systems to characterize properties. Both (K2-30b K2-34b) are bloated (1.25 $R_{\rm Jup}$ 1.33 Jup}$) around relatively...
LHS1070 is a nearby multiple system of low mass stars. It an important source information for probing the end main sequence, down to hydrogen-burning limit. The primary mid-M dwarf and two components are late-M early L dwarfs, at star-brown transition. Hence valuable object understand onset dust formation in cool stellar atmospheres.This work aims determining fundamental parameters test recent model atmospheres: BT-Dusty,BT-Settl, DRIFT, MARCS models.Unlike previous studies, we have...
Although mid-to-late type M dwarfs are the most common stars in our stellar neighborhood, knowledge of these objects is still limited. Open questions include evolution their angular momentum, internal structures, dust settling atmospheres, age dispersion within populations. In addition, at young ages, late-type Ms have masses below hydrogen burning limit and therefore key debate on brown dwarf mechanism formation. this work we determine study detail physical parameters two samples young,...
ABSTRACT Mt Abu Faint Object Spectrograph and Camera (MFOSC-P) is an in-house-developed instrument for the Physical Research Laboratory (PRL) 1.2 m telescope at Abu, India, commissioned in 2019 February. Here we present first science results derived from low-resolution spectroscopy programme of a sample M dwarfs carried out during commissioning run MFOSC-P between February June. carry great significance exoplanet searches habitable zone are among promising candidates observatory’s several...