Publications (70)
WIYN Open Cluster Study. XXVI. Improved kinematic membership and spectroscopy of IC 2391
I. Platais, C. Melo, J. -C. Mermilliod +5
[Abridged] Contex. Young open clusters provide important clues to the interface between the main sequence and pre-main-sequence phases of stellar evolution. The young and nearby op…
A homogeneous spectroscopic analysis of host stars of transiting planets
M. Ammler-von Eiff, N. C. Santos, S. G. Sousa +5
The analysis of transiting extra-solar planets provides an enormous amount of information about the formation and evolution of planetary systems. A precise knowledge of the host st…
A new Neptune-mass planet orbiting HD 219828
C. Melo, N. C. Santos, W. Gieren +10
Two years ago a new benchmark for the planetary survey was set with the discoveries of three extrasolar planets with masses below 20. In particular, the serendipitous dis…
Evidence for a spectroscopic direct detection of reflected light from 51 Peg b
J. H. C. Martins, N. C. Santos, P. Figueira +11
The detection of reflected light from an exoplanet is a difficult technical challenge at optical wavelengths. Even though this signal is expected to replicate the stellar signal, n…
Hot Exoplanet Atmospheres Resolved with Transit Spectroscopy (HEARTS) VIII. Nondetection of sodium in the atmosphere of the aligned planet KELT-10b
M. Steiner, O. Attia, D. Ehrenreich +17
We searched for potential atmospheric species in KELT-10b, focusing on sodium doublet lines (Na i; 589 nm) and the Balmer alpha line (H ; 656 nm) in the transmission spectrum.…
Precise masses for the transiting planetary system HD 106315 with HARPS
S. C. C. Barros, H. Gosselin, J. Lillo-Box +45
The multi-planetary system HD 106315 was recently found in K2 data . The planets have periods of and days, and radii of a…
Does rotation of B stars depend on metallicity? preliminary results from GIRAFFE spectra
F. Royer, P. North, C. Melo +4
We show the vsini distribution of main sequence B stars in sites of various metallicities, in the absolute magnitude range -3.34 < Mv < -2.17. These include Galactic stars in the f…
Hot Exoplanet Atmospheres Resolved with Transit Spectroscopy (HEARTS) III. Atmospheric structure of the misaligned ultra-hot Jupiter WASP-121b
V. Bourrier, D. Ehrenreich, M. Lendl +21
Ultra-hot Jupiters offer interesting prospects for expanding our theories on dynamical evolution and the properties of extremely irradiated atmospheres. In this context, we present…
High resolution spectroscopy of stars with transiting planets. The cases of OGLE-TR-10, 56, 111, 113, and TrES-1
N. C Santos, F. Pont, C. Melo +7
Context: During the past years photometric surveys, later complemented by follow-up radial-velocity measurements, have revealed the presence of several new extra-solar transiting p…
Chemical abundances for the transiting planet host stars OGLE-TR-10, 56, 111, 113, 132 and TrES-1. Abundances in different galactic populations
N. C. Santos, A. Ecuvillon, G. Israelian +6
We used the UVES spectrograph (VLT-UT2 telescope) to obtain high-resolution spectra of 6 stars hosting transiting planets, namely for OGLE-TR-10, 56, 111, 113, 132 and TrES-1. The…
Search for giant planets in M67 IV: survey results
A. Brucalassi, J. Koppenhoefer, R. Saglia +9
We present the results of a seven-year-long radial velocity survey of a sample of 88 main-sequence and evolved stars to reveal signatures of Jupiter-mass planets in the solar-age a…
Search for giant planets in M67 I. Overview
L. Pasquini, A. Brucalassi, M. T. Ruiz +7
Precise stellar radial velocities are used to search for massive (Jupiter masses or higher) exoplanets around the stars of the open cluster M67. We aim to obtain a census of massiv…
An extreme planetary system around HD219828. One long-period super Jupiter to a hot-neptune host star
N. C. Santos, A. Santerne, J. P. Faria +19
With about 2000 extrasolar planets confirmed, the results show that planetary systems have a whole range of unexpected properties. We present a full investigation of the HD219828 s…
Gravitational redshifts in main-sequence and giant stars
L. Pasquini, C. Melo, C. Chavero +4
Gravitational redshifts in solar-type main-sequence stars are expected to be some 500 ms greater than those in giants. Such a signature is searched for between groups of ope…
High Cadence Near Infrared Timing Observations of Extrasolar Planets: I. GJ 436b and XO-1b
C. Caceres, V. D. Ivanov, D. Minniti +5
Currently the only technique sensitive to Earth mass planets around nearby stars (that are too close for microlensing) is the monitoring of the transit time variations of the trans…
Hot Exoplanet Atmospheres Resolved with Transit Spectroscopy (HEARTS) VI. Non-detection of sodium with HARPS on the bloated super-Neptune WASP-127b
J. V. Seidel, M. Lendl, V. Bourrier +17
WASP-127b is one of the puffiest exoplanets found to date, with a mass only Neptune masses, but a radius larger than Jupiter. It is also located at the border of the Neptune…
Chasing extreme planetary architectures: I- HD196885Ab, a super-Jupiter dancing with two stars?
G. Chauvin, M. Videla, H. Beust +21
Planet(s) in binaries are unique architectures for testing predictions of planetary formation and evolution theories in very hostile environments. We used the IRDIS dual-band image…
The HARPS search for southern extrasolar planets XXV. Results from the metal-poor sample
N. C. Santos, M. Mayor, X. Bonfils +10
Searching for extrasolar planets around stars of different metallicity may provide strong constraints to the models of planet formation and evolution. In this paper we present the…
TOI-674b: an oasis in the desert of exo-Neptunes transiting a nearby M dwarf
F. Murgas, N. Astudillo-Defru, X. Bonfils +59
We use TESS, Spitzer, ground-based light curves and HARPS spectrograph radial velocity measurements to establish the physical properties of the transiting exoplanet candidate TOI-6…
OGLE-TR-211 - a new transiting inflated hot Jupiter from the OGLE survey and ESO LP666 spectroscopic follow-up program
A. Udalski, F. Pont, D. Naef +24
We present results of the photometric campaign for planetary and low-luminosity object transits conducted by the OGLE survey in 2005 season (Campaign #5). About twenty most promisi…
A transiting planet among 23 new near-threshold candidates from the OGLE survey - OGLE-TR-182
F. Pont, O. Tamuz, A. Udalski +24
By re-processing the data of the second season of the OGLE survey for planetary transits and adding new mesurements on the same fields gathered in subsequent years with the OGLE te…
The HARPS search for southern extra-solar planets XL. Searching for Neptunes around metal-poor stars
J. P. Faria, N. C. Santos, P. Figueira +14
Stellar metallicity -- as a probe of the metallicity of proto-planetary disks -- is an important ingredient for giant planet formation, likely through its effect on the timescales…
Trumpler 20 - an old and rich open cluster
I. Platais, C. Melo, J. P. Fulbright +4
We show that the open cluster Trumpler 20, contrary to the earlier findings, is actually an old Galactic open cluster. New CCD photometry and high-resolution spectroscopy are used…
Do stellar magnetic cycles influence the measurement of precise radial velocities?
N. C. Santos, J. Gomes da Silva, C. Lovis +1
The ever increasing level of precision achieved by present and future radial-velocity instruments is opening the way to discovering very low-mass, long-period planets (e.g. solar-s…
Hot Exoplanet Atmospheres Resolved with Transit Spectroscopy (HEARTS) - II. A broadened sodium feature on the ultra-hot giant WASP-76b
J. V. Seidel, D. Ehrenreich, A. Wyttenbach +18
High-resolution optical spectroscopy is a powerful tool to characterise exoplanetary atmospheres from the ground. The sodium D lines, with their large cross sections, are especiall…
Common Proper Motion Search for Faint Companions Around Early-Type Field Stars - Progress Report - II
Valentin D. Ivanov, D. Nuernberger, G. Chauvin +6
The multiplicity of early-type stars is still not well established. The studies of individual star forming regions suggest a connection with the age and the environment. To fill in…
Evidence for an MHD disk wind via optical forbidden line spectro-astrometry
E. T Whelan, I. Pascucci, U. Gorti +4
Spectro-astrometry is used to investigate the low velocity component (LVC) of the optical forbidden emission from the T Tauri stars RU Lupi and AS 205 N. Both stars also have high…
Connecting RS OPh to [some] Type Ia Supernovae
F. Patat, N. N. Chugai, Ph. Podsiadlowski +3
Aims: Recurrent nova systems like RS Oph have been proposed as a possible channel to Type Ia Supernova explosions, based on the high mass of the accreting white dwarf. Additional s…
Doppler follow-up of OGLE planetary transit candidates in Carina
F. Pont, F. Bouchy, C. Melo +4
We present the results of our high-resolution spectroscopic follow-up of 42 planetary transit candidates in Carina from the OGLE survey. This follow-up has already allowed the disc…
Detection of strong activity in the eclipsing binary brown dwarf 2MASSJ05352184-0546085 - A possible explanation for the temperature reversal
A. Reiners, A. Seifahrt, K. G. Stassun +2
We show high resolution spectra of the eclipsing brown dwarf binary 2MASSJ05352184-0546085 taken at the two opposite radial velocity maxima. Comparisons of the TiO bands to model a…
Detecting ring systems around exoplanets using high resolution spectroscopy: the case of 51Pegb
N. C. Santos, J. H. C. Martins, G. Boué +13
In this paper we explore the possibility that the recently detected reflected light signal of 51\,Peg\,b could be caused by a ring system around the planet. We use a simple model t…
Search for associations containing young stars (SACY):II. Chemical abundances of stars in 11 young Associations in the Solar neighborhood
P. Viana Almeida, N. C. Santos, C. Melo +5
The recently discovered coeval, moving groups of young stellar objects in the solar neighborhood represent invaluable laboratories to study recent star formation and to search for…
Chemical abundances in six nearby star-forming regions: implications for galactic evolution and planet searches around very young stars
N. C. Santos, C. Melo, D. J. James +3
In this paper we present a study of chemical abundances in six star-forming regions. Stellar parameters and metallicities are derived using high-resolution, high S/N spectra of wea…
Fluorine abundances in dwarf stars of the solar neighbourhood
A. Recio-Blanco, P. de Laverny, C. Worley +3
In spite of many observational efforts aiming to characterize the chemical evolution of our Galaxy, not much is known about the origin of fluorine (F). Models suggest that the F fo…
Optical phase curve of the ultra-hot Jupiter WASP-121b
V. Bourrier, D. Kitzmann, T. Kuntzer +28
We present the analysis of TESS optical photometry of WASP-121b, which reveal the phase curve of this transiting ultra-hot Jupiter. Its hotspot is located at the substellar point,…
Radial velocity information content of M dwarf spectra in the near-infrared
P. Figueira, V. Zh. Adibekyan, M. Oshagh +7
Aims: We evaluate the radial velocity (RV) information content and achievable precision on M0-M9 spectra covering the ZYJHK bands. We do so while considering both a perfect atmosph…
Finding proto-spectroscopic binaries: Precise multi-epoch radial velocities of 7 protostars in rho-Ophiuchus
P. Viana Almeida, C. Melo, N. C. Santos +3
The formation of spectroscopic binaries (SB) may be a natural byproduct of star formation. The early dynamical evolution of multiple stellar systems after the initial fragmentation…
Spectroscopy of Very Low Mass Stars and Brown Dwarfs in the Lambda Orionis Star Forming Region. I. Enlarging the census down to the planetary mass domain in Collinder 69
A. Bayo, D. Barrado, J. Stauffer +7
Whilst there is a generally accepted evolutionary scheme for the formation of low-mass stars, the analogous processes when moving down in mass to the brown dwarfs regime are not ye…
Hot Exoplanet Atmospheres Resolved with Transit Spectroscopy (HEARTS) V. Detection of sodium on the bloated super-Neptune WASP-166b
J. V. Seidel, D. Ehrenreich, V. Bourrier +17
Planet formation processes or evolution mechanisms are surmised to be at the origin of the hot Neptune desert. Studying exoplanets currently living within or at the edge of this de…
TOI-269 b: An eccentric sub-Neptune transiting a M2 dwarf revisited with ExTrA
M. Cointepas, J. M. Almenara, X. Bonfils +59
We present the confirmation of a new sub-Neptune close to the transition between super-Earths and sub-Neptunes transiting the M2 dwarf TOI- 269 (TIC 220479565, V = 14.4 mag, J = 10…
Characterization of the Nearby L/T Binary Brown Dwarf WISE J104915.57-531906.1 at 2 Parsecs from the Sun
A. Y. Kniazev, P. Vaisanen, K. Muzic +22
WISE J104915.57531906.1 is a L/T brown dwarf binary located 2pc from the Sun. The pair contains the closest known brown dwarfs and is the third closest known system, stellar or…
The effects of differential reddening and stellar rotation on the appearance of multiple populations in star clusters: the case of Trumpler 20
I. Platais, C. Melo, S. N. Quinn +6
We present a detailed analysis of the upper main sequence of the 1.3 Gyr old open cluster Trumpler 20. High accuracy BV photometry combined with the Very Large Telescope/FLAMES med…
The VLT/NaCo Large program to probe the occurrence of exoplanets and brown dwarfs in wide orbits: I- Sample definition and characterization
S. Desidera, E. Covino, S. Messina +28
Young, nearby stars are ideal targets to search for planets using the direct imaging technique. The determination of stellar parameters is crucial for the interpretation of imaging…
Common Proper Motion Search for Faint Companions Around Early-Type Field Stars - Progress Report
Valentin D. Ivanov, G. Chauvin, C. Foellmi +5
The multiplicity of early-type stars is still not well established. The derived binary fraction is different for individual star forming regions, suggesting a connection with the a…
A ground-based Ks-band detection of the thermal emission from the transiting exoplanet WASP-4b
C. Caceres, V. D. Ivanov, D. Minniti +6
Secondary eclipses are a powerful tool to measure directly the thermal emission from extrasolar planets, and to constrain their type and physical parameters. We started a project t…
The HARPS search for southern extra-solar planets XXXV. The interesting case of HD41248: stellar activity, no planets?
N. C. Santos, A. Mortier, J. P. Faria +21
The search for planets orbiting metal-poor stars is of uttermost importance for our understanding of the planet formation models. However, no dedicated searches have been conducted…
Abundance analysis of 5 early-type stars in the young open cluster IC2391
Ch. Stuetz, S. Bagnulo, E. Jehin +4
It is unclear whether chemically peculiar stars of the upper main sequence represent a class completely distinct from normal A-type stars, or whether there exists a continuous tran…
Evidence of a substellar companion around a very young T Tauri star
P. Viana Almeida, J. F. Gameiro, P. P. Petrov +4
We present results from a Near Infrared multi-epoch spectroscopic campaign to detect a young low-mass companion to a T Tauri star. AS 205A is a late-type dwarf (~K5) of ~1 Msun tha…
Hot Exoplanet Atmospheres Resolved with Transit Spectroscopy (HEARTS) I. Detection of hot neutral sodium at high altitudes on WASP-49b
A. Wyttenbach, C. Lovis, D. Ehrenreich +13
High-resolution optical spectroscopy during the transit of HD 189733b, a prototypical hot Jupiter, allowed the resolution of the Na I D sodium lines in the planet, giving access to…
Detailed stellar activity analysis and modelling of GJ 832: Reassessment of the putative habitable zone planet GJ 832c
P. Gorrini, N. Astudillo-Defru, S. Dreizler +27
Context. Gliese 832 (GJ 832) is an M2V star hosting a massive planet on a decade-long orbit, GJ 832b, discovered by radial velocity (RV). Later, a super Earth or mini-Neptune orbit…
Search for giant planets in M67 III: excess of hot Jupiters in dense open clusters
A. Brucalassi, L. Pasquini, R. Saglia +10
Since 2008 we used high-precision radial velocity (RV) measurements obtained with different telescopes to detect signatures of massive planets around main-sequence and evolved star…
Hot Exoplanet Atmospheres Resolved with Transit Spectroscopy (HEARTS) IV. A spectral inventory of atoms and molecules in the high-resolution transmission spectrum of WASP-121 b
H. J. Hoeijmakers, J. V. Seidel, L. Pino +22
Aims: We survey the transmission spectrum of WASP-121 b for line-absorption by metals and molecules at high spectral resolution, and elaborate on existing interpretations of the op…
Three planetary companions around M67 stars
A. Brucalassi, L. Pasquini, R. Saglia +7
For the past six years we have carried out a search for massive planets around main sequence and evolved stars in the open cluster (OC) M67, using radial velocity (RV) measurements…
Doppler follow-up of OGLE transiting companions in the Galactic bulge
Francois Bouchy, F. Pont, C. Melo +4
Two years ago, the OGLE-III survey (Optical Gravitational Lensing Experiment) announced the detection of 54 short period multi-transiting objects in the Galactic bulge (Udalski et…
On the Age of Stars Harboring Transiting Planets
C. Melo, N. C. Santos, F. Pont +5
Results of photometric surveys have brought to light the existence of a population of giant planets orbiting their host stars even closer than the hot Jupiters (HJ), with orbital p…
A catalog of rotational and radial velocities for evolved stars. IV. Metal-poor stars
J. R. De Medeiros, J. R. P. Silva, J. D. Jr. do Nascimento +4
The present paper describes the first results of an observational program intended to refine and extend the existing vsini measurements of metal-poor stars, with anemphasis on fiel…
Accretion in low-mass members of the Orion Nebula Cluster with young transition disks
R. M. G. de Albuquerque, J. F. Gameiro, S. H. P. Alencar +3
Although the Orion Nebula Cluster is one of the most studied clusters in the solar neighborhood, the evolution of the very low-mass members () has not been f…
The Gaia-ESO Survey: A new approach to chemically characterising young open clusters II. Abundances of the neutron-capture elements Cu, Sr, Y, Zr, Ba, La, and Ce
M. Baratella, V. D'Orazi, V. Sheminova +32
Young open clusters (t<200 Myr) have been observed to exhibit several peculiarities in their chemical compositions, from a slightly sub-solar iron content, super-solar abundances o…
The HARPS search for southern extrasolar planets XXI. Three new giant planets orbiting the metal-poor stars HD5388, HD181720, and HD190984
N. C. Santos, M. Mayor, W. Benz +11
We present the discovery of three new giant planets around three metal-deficient stars: HD5388b (1.96M_Jup), HD181720b (0.37M_Jup), and HD190984b (3.1M_Jup). All the planets have m…
The transiting planet OGLE-TR-132b revisited with new spectroscopy and deconvolution photometry
M. Gillon, F. Pont, C. Moutou +8
OGLE-TR-132b transits a very metal-rich F dwarf about 2000 pc from the Sun, in the Galactic disc towards Carina. It orbits very close to its host star (a = 0.03 AU) and has an equi…
A hot terrestrial planet orbiting the bright M dwarf L 168-9 unveiled by TESS
N. Astudillo-Defru, R. Cloutier, S. X. Wang +67
We report the detection of a transiting super-Earth-sized planet (R=1.39+-0.09 Rearth) in a 1.4-day orbit around L 168-9 (TOI-134),a bright M1V dwarf (V=11, K=7.1) located at 25.15…
Spectroscopy of Very Low Mass Stars and Brown Dwarfs in the Lambda Orionis Star Forming Region
A. Bayo, D. Barrado, N. Huélamo +4
Context. Most observational studies so far point towards brown dwarfs sharing a similar formation mechanism as the one accepted for low mass stars. However, larger databases and mo…
Two new "very hot Jupiters" among the OGLE transiting candidates
F. Bouchy, F. Pont, N. C. Santos +4
As a result of a radial velocity follow-up of OGLE planetary transit candidates in Carina, we report the discovery of two new transiting planets with very short orbital periods: OG…
Search for Associations Containing Young stars (SACY): Chemical tagging IC 2391 & the Argus association
G. M. De Silva, V. D'Orazi, C. Melo +4
We explore the possible connection between the open cluster IC 2391 and the unbound Argus association identified by the SACY survey. In addition to common kinematics and ages betwe…
High-Dimensional Quantum Key Distribution via full Core-mode Encoding over Deployed Multicore Fibers
G. H. dos Santos, K. B. Sawada, N. Villalba +11
Quantum key distribution (QKD) provides information-theoretic security rooted in quantum physics, while high-dimensional (HD) encoding increases both noise tolerance and secret-key…
The HARPS search for southern extra-solar planets. XXXIX. HD175607 b, the most metal-poor G dwarf with an orbiting sub-Neptune
A. Mortier, J. P. Faria, N. C. Santos +16
Context. The presence of a small-mass planet (M0.1\,M) seems, to date, not to depend on metallicity, however, theoretical simulations have shown that stars with subsol…
Recovering the colour-dependent albedo of exoplanets with high-resolution spectroscopy: from ESPRESSO to the ELT
J. H. C. Martins, P. Figueira, N. C. Santos +5
The characterization of planetary atmospheres is a daunting task, pushing current observing facilities to their limits. The next generation of high-resolution spectrographs mounted…
Early-type stars observed in the ESO UVES Paranal Observatory Project: I -- Interstellar Na I UV, Ti II and Ca II K observations
I. Hunter, J. V. Smoker, F. P. Keenan +5
We present an analysis of interstellar Na I (lambda=3302.37Ã , 3302.98Ã ), Ti II (lambda=3383.76Ã ) and Ca II K (lambda=3933.66Ã ) absorption features for 74 sightlines towards O-…
Nowcasting the turbulence at the Paranal Observatory
J. Milli, R. Gonzalez, P. R. Fluxa +13
At Paranal Observatory, the least predictable parameter affecting the short-term scheduling of astronomical observations is the optical turbulence, especially the seeing, coherence…
The cool atmospheres of the binary brown dwarf eps Indi B
M. F. Sterzik, E. Pantin, M. Hartung +7
We have imaged Indi B, the closest brown dwarf binary known, with VISIR at the VLT in three narrow-band mid-infrared bandpasses located around 8.6m, 10.5m and 11.3…