Results for "G. Anglada-Escudé"

total 117636took 0.20s
The habitability of Proxima Centauri b II. Possible climates and ObservabilityAug 24 2016Sep 28 2016Radial velocity monitoring has found the signature of a $M \sin i = 1.3$~M$_\oplus$ planet located within the Habitable Zone (HZ) of Proxima Centauri \citep{Anglada16}. Despite a hotter past and an active host star the planet Proxima~b could have retained ... More
Red Dots: A temperate 1.5 Earth-mass planet in a compact multi-terrestrial planet system around GJ1061Aug 13 2019Small low-mass stars are favourable targets for the detection of rocky habitable planets. In particular, planetary systems in the solar neighbourhood are interesting and suitable for precise characterisation. The Red Dots campaigns seek to discover rocky ... More
Flat-relative optimal extraction. A quick and efficient algorithm for stabilised spectrographsNov 20 2013Optimal extraction is a key step in processing the raw images of spectra as registered by two-dimensional detector arrays to a one-dimensional format. Previously reported algorithms reconstruct models for a mean one-dimensional spatial profile to assist ... More
A planetary system around the nearby M dwarf GJ 667C with at least one super-Earth in its habitable zoneFeb 02 2012We re-analyze 4 years of HARPS spectra of the nearby M1.5 dwarf GJ 667C available through the ESO public archive. The new radial velocity (RV) measurements were obtained using a new data analysis technique that derives the Doppler measurement and other ... More
ALMA Discovery of Dust Belts Around Proxima CentauriNov 02 2017Proxima Centauri, the star closest to our Sun, is known to host at least one terrestrial planet candidate in a temperate orbit. Here we report the ALMA detection of the star at 1.3 mm wavelength and the discovery of a belt of dust orbiting around it at ... More
Water vapor detection in the transmission spectra of HD 209458 b with the CARMENES NIR channelAug 23 2019Aims: We aim at detecting H$_2$O in the atmosphere of the hot Jupiter HD 209458 b and perform a multi-band study in the near infrared with CARMENES. Methods: The H$_2$O absorption lines from the planet's atmosphere are Doppler-shifted due to the large ... More
A planetary system with gas giants and super-Earths around the nearby M dwarf GJ 676A. Optimizing data analysis techniques for the detection of multi-planetary systemsJun 29 2012Oct 15 2012Several M dwarfs are targets of systematical monitoring in searches for Doppler signals caused by low-mass exoplanet companions. As a result, an emerging population of high-multiplicity planetary systems around low-mass stars are being detected as well. ... More
Comment on "Stellar activity masquerading as planets in the habitable zone of the M dwarf Gliese 581"Mar 06 2015Robertson et al.(Reports, July 25 2014, p440-444)(1) claimed that activity-induced variability is responsible for the Doppler signal of the proposed planet candidate GJ 581d. We point out that their analysis using periodograms of residual data is incorrect, ... More
The origin of the excess transit absorption in the HD 189733 system: planet or star?Jul 13 2016Jul 14 2016We have detected excess absorption in the emission cores of Ca II H & K during transits of HD 189733b for the first time. Using observations of three transits we investigate the origin of the absorption, which is also seen in H{\alpha} and the Na I D ... More
Aliases of the first eccentric harmonic : Is GJ 581g a genuine planet candidate?Oct 31 2010Apr 29 2011The radial velocity (RV) method for detecting extrasolar planets has been the most successful to date. The RV signal imprinted by a few Earth-mass planet around a cool star is at the limit of the typical single measurement uncertainty obtained using state-of-the-art ... More
The HARPS-TERRA project I. Description of the algorithms, performance and new measurements on a few remarkable stars observed by HARPSFeb 12 2012Apr 19 2012Doppler spectroscopy has uncovered or confirmed all the known planets orbiting nearby stars. Two main techniques are used to obtain precision Doppler measurements at optical wavelengths. The first approach is the gas cell method, which consists on the ... More
Trigonometric Parallaxes and Proper Motions of 134 Southern Late M, L, and T Dwarfs from the Carnegie Astrometric Planet Search ProgramApr 19 2016We report trigonometric parallaxes for 134 low mass stars and brown dwarfs, of which 38 have no previously published measurement and 79 more have improved uncertainties. Our survey targeted nearby targets, so 119 are closer than 30 pc. Of the 38 stars ... More
Gravitational Lensing Effects on the Baryonic Acoustic Oscillation Signature in the Redshift-Space Correlation FunctionJan 07 2009Aug 07 2010Measurements of the baryonic acoustic oscillation (BAO) peak in the redshift-space correlation function yield the angular diameter distance D_A(z) and the Hubble parameter H(z) as a function of redshift, constraining the properties of dark energy and ... More
Distance and Kinematics of the TW Hydrae Association from ParallaxesNov 09 2012From common proper motion and signatures of youth, researchers have identified about 30 members of a putative TW Hydrae Association. Only four of these had parallactic distances from Hipparcos. We have measured parallaxes and proper motions for 14 primary ... More
Evidence of a massive planet candidate orbiting the young active K5V star BD+20 1790Dec 14 2009BD+20 1790 is a young active, metal-rich, late-type K5Ve star. We have undertaken a study of stellar activity and kinematics for this star over the past few years. Previous results show a high level of stellar activity, with the presence of prominence-like ... More
Bosonic dark matter halos: excited states and relaxation in the potential of the ground stateFeb 28 2018An ultra-light axion field with mass $\sim 10^{-22}\ {\rm eV}$, also known as wave or fuzzy dark matter, has been proposed as a component of the dark matter in the Universe. We study the evolution of the axion dark matter distribution in the central region ... More
The Anglo-Australian Planet Search XXV: A Candidate Massive Saturn Analog Orbiting HD 30177Dec 06 2016We report the discovery of a second long-period giant planet orbiting HD 30177, a star previously known to host a massive Jupiter analog (HD 30177b: a=3.8$\pm$0.1 au, m sin $i=9.7\pm$0.5 Mjup). HD 30177c can be regarded as a massive Saturn analog in this ... More
Absolute properties of the low-mass eclipsing binary CM DraconisOct 08 2008Spectroscopic and eclipsing binary systems offer the best means for determining accurate physical properties of stars, including their masses and radii. The data available for low-mass stars have yielded firm evidence that stellar structure models predict ... More
The Kapteyn moving group is not tidal debris from $ω$ CentauriJun 05 2015Aug 21 2015The Kapteyn moving group has been postulated as tidal debris from $\omega$ Centauri. If true, members of the group should show some of the chemical abundance patterns known for stars in the cluster. We present an optical and near-infrared high-resolution, ... More
Prospects for detecting the astrometric signature of Barnard's Star bNov 14 2018Mar 06 2019A low-amplitude periodic signal in the radial velocity (RV) time series of Barnard's Star was recently attributed to a planetary companion with a minimum mass of ${\sim}$3.2 $M_\oplus$ at an orbital period of $\sim$233 days. The relatively long orbital ... More
GJ 1214b revised. Improved trigonometric parallax, stellar parameters, orbital solution, and bulk properties for the super-Earth GJ 1214bOct 30 2012Dec 12 2012GJ 1214 is orbited by a transiting super-Earth-mass planet. It is a primary target for ongoing efforts to understand the emerging population of super-Earth-mass planets around M dwarfs. We present new precision astrometric measurements, a re-analysis ... More
Bayesian search for low-mass planets around nearby M dwarfs. Estimates for occurrence rate based on global detectability statisticsMar 03 2014Due to their higher planet-star mass-ratios, M dwarfs are the easiest targets for detection of low-mass planets orbiting nearby stars using Doppler spectroscopy. Furthermore, because of their low masses and luminosities, Doppler measurements enable the ... More
High-cadence spectroscopy of M-dwarfs. I. Analysis of systematic effects in HARPS-N line profile measurements on the bright binary GJ 725A+BApr 18 2016Understanding the sources of instrumental systematic noise is a must to improve the design of future spectrographs. In this study, we alternated observations of the well-suited pair of M-stars GJ 725A+B to delve into the sub-night HARPS-N response. Besides ... More
The CARMENES search for exoplanets around M dwarfs: High-resolution optical and near-infrared spectroscopy of 324 survey starsNov 17 2017Feb 09 2018The CARMENES radial velocity (RV) survey is observing 324 M dwarfs to search for any orbiting planets. In this paper, we present the survey sample by publishing one CARMENES spectrum for each M dwarf. These spectra cover the wavelength range 520--1710nm ... More
The CARMENES search for exoplanets around M dwarfs - HD 147379b: A nearby Neptune in the temperate zone of an early-M dwarfDec 15 2017We report on the first star discovered to host a planet detected by radial velocity (RV) observations obtained within the CARMENES survey for exoplanets around M dwarfs. HD 147379 ($V = 8.9$ mag, $M = 0.58 \pm 0.08$ M$_{\odot}$), a bright M0.0V star at ... More
The CARMENES search for exoplanets around M dwarfs. First visual-channel radial-velocity measurements and orbital parameter updates of seven M-dwarf planetary systemsOct 04 2017Jan 30 2018Context: The main goal of the CARMENES survey is to find Earth-mass planets around nearby M-dwarf stars. Seven M-dwarfs included in the CARMENES sample had been observed before with HIRES and HARPS and either were reported to have one short period planetary ... More
Mock Quasar-Lyman-α Forest Data-sets for the SDSS-III Baryon Oscillation Spectroscopic SurveyDec 01 2014Nov 17 2015We describe mock data-sets generated to simulate the high-redshift quasar sample in Data Release 11 (DR11) of the SDSS-III Baryon Oscillation Spectroscopic Survey (BOSS). The mock spectra contain Ly{\alpha} forest correlations useful for studying the ... More
Two planetary companions around the K7 dwarf GJ 221 : a hot super-Earth and a candidate in the sub-Saturn desert rangeMay 09 2013We report two low mass companions orbiting the nearby K7 dwarf GJ 221 that have emerged from re-analyzing 4.4 years of publicly available HARPS spectra complemented with 2 years of high precision Doppler measurements with Magellan/PFS. The HARPS measurements ... More
GJ 832c: A super-earth in the habitable zoneJun 21 2014We report the detection of GJ 832c, a super-Earth orbiting near the inner edge of the habitable zone of GJ 832, an M dwarf previously known to host a Jupiter analog in a nearly-circular 9.4-year orbit. The combination of precise radial-velocity measurements ... More
A New Merging Double Degenerate Binary in the Solar NeighborhoodMar 01 2015Characterizing the local space density of double degenerate binary systems is a complementary approach to broad sky surveys of double degenerates to determine the expected rates of white dwarf binary mergers, in particular those that may evolve into other ... More
AD Leonis: Radial velocity signal of stellar rotation or spin-orbit resonance?Feb 16 2018Feb 21 2018AD Leonis is a nearby magnetically active M dwarf. We find Doppler variability with a period of 2.23 days as well as photometric signals: (1) a short period signal which is similar to the radial velocity signal albeit with considerable variability; and ... More
Statistical detection of a tidal stream associated with the globular cluster M68 using Gaia dataMay 03 2019A method to search for tidal streams and to fit their orbits based on maximum likelihood is presented and applied to the Gaia data. Tests of the method are performed showing how a simulated stream produced by tidal stripping of a star cluster is recovered ... More
Perspective acceleration and gravitational redshift. Measuring masses of individual white dwarfs using Gaia + SIM astrometryJul 22 2009According to current plans, the SIM/NASA mission will be launched just after the end of operations for the Gaia/ESA mission. This is a new situation which enables long term astrometric projects that could not be achieved by either mission alone. Using ... More
MagAO Imaging of Long-period Objects (MILO). II. A Puzzling White Dwarf around the Sun-like Star HD 11112Sep 08 2016HD 11112 is an old, Sun-like star that has a long-term radial velocity (RV) trend indicative of a massive companion on a wide orbit. Here we present direct images of the source responsible for the trend using the Magellan Adaptive Optics system. We detect ... More
Magnetic fields in M dwarfs from the CARMENES surveyApr 29 2019M dwarfs are known to generate the strongest magnetic fields among main-sequence stars with convective envelopes, but the link between the magnetic fields and underlying dynamo mechanisms, rotation, and activity still lacks a consistent picture. In this ... More
Frequency of planets orbiting M dwarfs in the Solar neighbourhoodJun 11 2019The most abundant stars in the Galaxy, M dwarfs, are very commonly hosts to diverse systems of low-mass planets. Their abundancy implies that the general occurrence rate of planets is dominated by their occurrence rate around such M dwarfs. In this article, ... More
The CARMENES search for exoplanets around M dwarfs. Activity indicators at visible and near-infrared wavelengthsJan 25 2019The CARMENES survey is searching for Earth-like planets orbiting M dwarfs using the radial velocity method. Studying the stellar activity of the target stars is important to avoid false planet detections and to improve our understanding of the atmospheres ... More
Analysis of combined radial velocities and activity of BD+20 1790: evidence supporting the existence of a planetary companionFeb 18 2015This paper presents the simultaneous Bayesian analysis of the radial velocity and activity indices for the K5Ve active star BD+20 1790, that was proposed to host a close-in massive planet by Hern\'an-Obispo et al. (2010). The Bayesian analysis supports ... More
The CARMENES search for exoplanets around M dwarfs. Two temperate Earth-mass planet candidates around Teegarden's StarJun 17 2019Sep 13 2019Context. Teegarden's Star is the brightest and one of the nearest ultra-cool dwarfs in the solar neighbourhood. For its late spectral type (M7.0V), the star shows relatively little activity and is a prime target for near-infrared radial velocity surveys ... More
A dynamically-packed planetary system around GJ667C with three super-Earths in its habitable zoneJun 25 2013Since low-mass stars have low luminosities, orbits at which liquid water can exist on Earth-sized planets are relatively close-in, which produces Doppler signals that are detectable using state-of-the-art Doppler spectroscopy. GJ 667C is already known ... More
High-cadence spectroscopy of M-dwarfs - II. Searching for stellar pulsations with HARPSMay 12 2017Stellar oscillations appear all across the Hertzsprung-Russell diagram. Recent theoretical studies support their existence also in the atmospheres of M dwarfs. These studies predict for them short periodicities ranging from 20~min to 3~h. Our Cool Tiny ... More
Rendering Elimination: Early Discard of Redundant Tiles in the Graphics PipelineJul 25 2018GPUs are one of the most energy-consuming components for real-time rendering applications, since a large number of fragment shading computations and memory accesses are involved. Main memory bandwidth is especially taxing battery-operated devices such ... More
On the effect of the ionising background on the Lyα forest autocorrelation functionApr 29 2014An analytical framework is presented to understand the effects of a fluctuating intensity of the cosmic ionising background on the correlations of the Ly{\alpha} forest transmission fraction measured in quasar spectra. In the absence of intensity fluctuations, ... More
Astrometry and radial velocities of the planet host M dwarf GJ 317: new trigonometric distance, metallicity and upper limit to the mass of GJ 317bNov 10 2011We have obtained precision astrometry of the planet hosting M dwarf GJ 317 in the framework of the Carnegie Astrometric Planet Search project. The new astrometric measurements give a distance determination of 15.3 pc, 65% further than previous estimates. ... More
He I $λ$ 10830 Å in the transmission spectrum of HD 209458 bJul 31 2019Context: Recently, the He I triplet at 10830 \r{A} has been rediscovered as an excellent probe of the extended and possibly evaporating atmospheres of close-in transiting planets. This has already resulted in detections of this triplet in the atmospheres ... More
The CARMENES search for exoplanets around M dwarfs. Chromospheric modeling of M2-3 V stars with PHOENIXFeb 11 2019Chromospheric modeling of observed differences in stellar activity lines is imperative to fully understand the upper atmospheres of late-type stars. We present one-dimensional parametrized chromosphere models computed with the atmosphere code PHOENIX ... More
Multiple water band detections in the CARMENES near-infrared transmission spectrum of HD 189733 bNov 21 2018Aims: We explore the capabilities of CARMENES for characterizing hot-Jupiter atmospheres by targeting multiple water bands, in particular, those at 1.15 and 1.4 $\mu$m. Hubble Space Telescope observations suggest that this wavelength region is relevant ... More
The CARMENES search for exoplanets around M dwarfs -- Photospheric parameters of target stars from high-resolution spectroscopy. II. Simultaneous multiwavelength range modeling of activity insensitive linesJul 01 2019We present precise photospheric parameters of 282 M dwarfs determined from fitting the most recent version of PHOENIX models to high-resolution CARMENES spectra in the visible (0.52 - 0.96 $\mu$m) and near-infrared wavelength range (0.96 - 1.71 $\mu$m). ... More
The CARMENES search for exoplanets around M dwarfs - The enigmatic planetary system GJ 4276: One eccentric planet or two planets in a 2:1 resonance?Jan 07 2019We report the detection of a Neptune-mass exoplanet around the M4.0 dwarf GJ 4276 (G 232-070) based on radial velocity (RV) observations obtained with the CARMENES spectrograph. The RV variations of GJ 4276 are best explained by the presence of a planetary ... More
Relativistic effects on the imaging by a rotating optical systemOct 07 2005Sep 05 2006Context. High accuracy astrometric instruments like Gaia aiming at an accuracy of 1 microarcsecond cannot be considered as point-like observers in the framework of relativistic modelling of observable quantities. Aims. Special-relativistic effects on ... More
High Angular Resolution Observations at 7-mm of the Core of the Quadrupolar HH 111/121 OutflowAug 23 2008We present sensitive, high angular resolution ($0\rlap.{''}05$) VLA continuum observations made at 7 mm of the core of the HH 111/121 quadrupolar outflow. We estimate that at this wavelength the continuum emission is dominated by dust, although a significant ... More
Quasar-Lyman $α$ Forest Cross-Correlation from BOSS DR11 : Baryon Acoustic OscillationsNov 07 2013May 20 2014We measure the large-scale cross-correlation of quasars with the Lyman alpha forest absorption, using over 164,000 quasars from Data Release 11 of the SDSS-III Baryon Oscillation Spectroscopic Survey. We extend the previous study of roughly 60,000 quasars ... More
The Lyman-alpha forest in three dimensions: measurements of large scale flux correlations from BOSS 1st-year dataApr 27 2011Aug 01 2011Using a sample of approximately 14,000 z>2.1 quasars observed in the first year of the Baryon Oscillation Spectroscopic Survey (BOSS), we measure the three-dimensional correlation function of absorption in the Lyman-alpha forest. The angle-averaged correlation ... More
Measurement of Baryon Acoustic Oscillations in the Lyman-alpha Forest Fluctuations in BOSS Data Release 9Jan 15 2013Mar 20 2013We use the Baryon Oscillation Spectroscopic Survey (BOSS) Data Release 9 (DR9) to detect and measure the position of the Baryonic Acoustic Oscillation (BAO) feature in the three-dimensional correlation function in the Lyman-alpha forest flux fluctuations ... More
An Ionized Outflow from AB Aur, a Herbig Ae Star with a Transitional DiskAug 29 2014AB Aur is a Herbig Ae star with a transitional disk. Transitional disks present substantial dust clearing in their inner regions, most probably because of the formation of one or more planets, although other explanations are still viable. In transitional ... More
Gliese 49: Activity evolution and detection of a super-EarthMar 12 2019Mar 25 2019Small planets around low-mass stars often show orbital periods in a range that corresponds to the temperate zones of their host stars which are therefore of prime interest for planet searches. Surface phenomena such as spots and faculae create periodic ... More
Gliese 49: Activity evolution and detection of a super-EarthMar 12 2019Small planets around low-mass stars often show orbital periods in a range that corresponds to the temperate zones of their host stars which are therefore of prime interest for planet searches. Surface phenomena such as spots and faculae create periodic ... More
Design and Construction of Absorption Cells for Precision Radial Velocities in the K Band using Methane IsotopologuesMay 07 2012We present a method to optimize absorption cells for precise wavelength calibration in the near-infrared. We apply it to design and optimize methane isotopologue cells for precision radial velocity measurements in the K band. We also describe the construction ... More
The one-dimensional Ly-alpha forest power spectrum from BOSSJun 25 2013Nov 20 2013We have developed two independent methods to measure the one-dimensional power spectrum of the transmitted flux in the Lyman-$\alpha$ forest. The first method is based on a Fourier transform, and the second on a maximum likelihood estimator. The two methods ... More
A survey for water maser emission towards planetary nebulae. New detection in IRAS 17347-3139Oct 15 2003We report on a water maser survey towards a sample of 27 planetary nebulae (PNe) using the Robledo de Chavela and Medicina single-dish antennas, as well as the Very Large Array (VLA). Two detections have been obtained: the already known water maser emission ... More
Penrose-like inequality with angular momentum for general horizonsOct 24 2018In axially symmetric space-times it is expected that the Penrose inequality can be strengthened to include angular momentum. In a recent work [2] we have proved a weaker version of this inequality for minimal surfaces, using the monotonicity of the Geroch ... More
Penrose-like inequality with angular momentum for minimal surfacesAug 15 2017Jan 25 2018In axially symmetric spacetimes the Penrose inequality can be strengthened to include angular momentum. We prove a version of this inequality for minimal surfaces, more precisely, a lower bound for the ADM mass in terms of the area of a minimal surface, ... More
Low-mass protostars and dense cores in different evolutionary stages in IRAS 00213+6530Aug 04 2009We aim at studying with high angular resolution a dense core associated with a low-luminosity IRAS source, IRAS 00213+6530, in order to investigate whether low mass star formation is really taking place in isolation. We performed observations at 1.2mm ... More
Baryon Acoustic Oscillations in the Ly-α forest of BOSS quasarsNov 12 2012Feb 14 2013We report a detection of the baryon acoustic oscillation (BAO) feature in the three-dimensional correlation function of the transmitted flux fraction in the \Lya forest of high-redshift quasars. The study uses 48,640 quasars in the redshift range $2.1\le ... More
On the nature of outflows in intermediate-mass protostars: a case study of IRAS 20050+2720Dec 11 2007Context. This is the third of a series of papers devoted to study in detail and with high-angular resolution intermediate-mass molecular outflows and their powering sources. Aims. The aim of this paper is to study the intermediate-mass YSO IRAS 20050+2720 ... More
The circumstellar disc around the Herbig AeBe star HD169142Nov 09 2005We present 7 mm and 3.5 cm wavelength continuum observations toward the Herbig AeBe star HD169142 performed with the Very Large Array (VLA) with an angular resolution of ~1". We find that this object exhibits strong (~4.4 mJy), unresolved (~1") 7 mm continuum ... More
The transverse velocity and excitation structure of the HH 110 jetFeb 04 2003We present long-slit spectroscopic observations of the HH 110 jet obtained with the 4.2~m William Herschel Telescope. We have obtained for the first time, spectra for slit positions along and across the jet axis (at the position of knots B, C, I, J and ... More
The Radio Jet Associated with the Multiple V380 Ori SystemJun 01 2016The giant Herbig-Haro object 222 extends over $\sim$6$'$ in the plane of the sky, with a bow shock morphology. The identification of its exciting source has remained uncertain over the years. A non-thermal radio source located at the core of the shock ... More
Proper Motions of Thermal Radio Sources near HH 7-11 in the NGC 1333 Star Forming RegionSep 01 2008Star forming regions are expected to show linear proper motions due to the relative motion of the Sun with respect to the region. These proper motions appear superposed to the proper motions expected in features associated with mass ejection from the ... More
Imaging the photoevaporating disk and radio jet of GM AurJul 14 2016Photoevaporation is probably the main agent for gas dispersal during the last stages of protoplanetary disk evolution. However, the overall mass loss rate in the photoevaporative wind and its driving mechanism are still not well understood. Here we report ... More
Multiple rings in the transitional disk of GM Aurigae revealed by VLA and ALMAAug 06 2018Our understanding of protoplanetary disks is rapidly departing from the classical view of a smooth, axisymmetric disk. This is in part thanks to the high angular resolution that (sub)mm observations can provide. Here we present the combined results of ... More
Analysis and test of the central-blue-spot infall hallmarkApr 24 2019The infall of material onto a protostar, in the case of optically thick line emission, produces an asymmetry in the blue- and red-wing line emission. For an angularly resolved emission, this translates in a blue central spot in the first-order moment ... More
The Sloan Digital Sky Survey quasar catalog: tenth data releaseNov 19 2013We present the Data Release 10 Quasar (DR10Q) catalog from the Baryon Oscillation Spectroscopic Survey (BOSS) of the Sloan Digital Sky Survey III. The catalog includes all BOSS objects that were targeted as quasar candidates during the first 2.5 years ... More
A new radial system of dark globules in MonocerosNov 24 2005Aims. We analyze the LBN 978 HII region in order to study the HII/molecular cloud interaction. Methods. We used the IAC-80 telescope to image the region with narrow-band filters and the Very Large Array to obtain a radio continuum map at 3.6 cm. We also ... More
Dense gas and the nature of the outflowsJan 13 2011We present the results of the observations of the (J,K)=(1,1) and the (J,K)=(2,2) inversion transitions of the NH3 molecule toward a large sample of 40 regions with molecular or optical outflows, using the 37 m radio telescope of the Haystack Observatory. ... More
Water maser kinematics in massive star-forming regions: Cepheus A and W75NApr 17 2012VLBI multi-epoch water maser observations are a powerful tool to study the dense, warm shocked gas very close to massive protostars. The very high-angular resolution of these observations allow us to measure the proper motions of the masers in a few weeks, ... More
A bright radio HH object with large proper motions in the massive star-forming region W75NApr 07 2010We analyze radio continuum and line observations from the archives of the Very Large Array, as well as X-ray observations from the \emph{Chandra} archive of the region of massive star formation W75N. Five radio continuum sources are detected: VLA 1, VLA ... More
Dynamical Masses of Eps Ind B and C: Two Massive Brown Dwarfs at the Edge of the Stellar-Substellar BoundaryJul 25 2018We report individual dynamical masses for the brown dwarfs Epsilon Indi B and C, which have spectral types of T1.5 and T6, respectively, measured from astrometric orbit mapping. Our measurements are based on a joint analysis of astrometric data from the ... More
The Brown Dwarf Kinematics Project (BDKP). III. Parallaxes for 70 Ultracool DwarfsMar 25 2012We report parallax measurements for 70 ultracool dwarfs (UCDs). Using both literature values and our sample, we report new polynomial relations between spectral type and M$_{JHK}$. Including resolved L/T transition binaries in the relations, we find no ... More
A candidate super-Earth planet orbiting near the snow line of Barnard's starNov 14 2018Nov 23 2018At a distance of 1.8 parsecs, Barnard's star (Gl 699) is a red dwarf with the largest apparent motion of any known stellar object. It is the closest single star to the Sun, second only to the alpha Centauri triple stellar system. Barnard's star is also ... More
Strategic research fundingMar 21 2019We study a dynamic game in which information arrives gradually as long as a principal funds research, and an agent takes an action in each period. In equilibrium, the principal's patience is the key determinant of her information provision: the lower ... More
The Invisible Tension of the Universe from Astrophysical Black Holes: a Solution to the Coincidence Problem of the Accelerated ExpansionMar 31 2010Astronomical observations have shown that the expansion of the universe is at present accelerating, consistently with a constant negative pressure or tension. This is a major puzzle because we do not understand why this tension is so small compared to ... More
Stellar activity analysis of Barnard's Star: Very slow rotation and evidence for long-term activity cycleDec 17 2018Jul 23 2019The search for Earth-like planets around late-type stars using ultra-stable spectrographs requires a very precise characterization of the stellar activity and the magnetic cycle of the star, since these phenomena induce radial velocity (RV) signals that ... More
Quasar -- CIV forest cross-correlation with SDSS DR12Dec 28 2017Jul 06 2018We present a new determination of the large-scale clustering of the CIV forest (i.e., the absorption due to all CIV absorbers) using its cross-correlation with quasars in the Sloan Digital Sky Survey (SDSS) Data Release 12 (DR12). We fit a linear bias ... More
Stellar activity analysis of Barnard's Star: Very slow rotation and evidence for long-term activity cycleDec 17 2018Aug 06 2019The search for Earth-like planets around late-type stars using ultra-stable spectrographs requires a very precise characterization of the stellar activity and the magnetic cycle of the star, since these phenomena induce radial velocity (RV) signals that ... More
Retrieval of Precise Radial Velocities from Near-Infrared High Resolution Spectra of Low Mass StarsMar 18 2016Given that low-mass stars have intrinsically low luminosities at optical wavelengths and a propensity for stellar activity, it is advantageous for radial velocity (RV) surveys of these objects to use near-infrared (NIR) wavelengths. In this work we describe ... More
Proxima Centauri b is not a transiting exoplanetMay 03 2019We report Spitzer Space Telescope observations during predicted transits of the exoplanet Proxima Centauri b. As the nearest terrestrial habitable-zone planet we will ever discover, any potential transit of Proxima b would place strong constraints on ... More
Stellar activity analysis of Barnard's Star: Very slow rotation and evidence for long-term activity cycleDec 17 2018The search for Earth-like planets around late-type stars using ultra-stable spectrographs requires a very precise characterization of the stellar activity and the magnetic cycle of the star, since these phenomena induce radial velocity (RV) signals that ... More
Benchmarking the power of amateur observatories for TTV exoplanets detectionJan 27 2015Apr 08 2015We perform an analysis of ~80000 photometric measurements for the following 10 stars hosting transiting planets: WASP-2, -4, -5, -52, Kelt-1, CoRoT-2, XO-2, TrES-1, HD 189733, GJ 436. Our analysis includes mainly transit lightcurves from the Exoplanet ... More
The CARMENES search for exoplanets around M dwarfs: A low-mass planet in the temperate zone of the nearby K2-18May 02 2018May 04 2018K2-18 is a nearby M2.5 dwarf, located at 34 pc and hosting a transiting planet which was first discovered by the {\it K2} mission and later confirmed with {\it Spitzer Space Telescope} observations. With a radius of $\sim 2 \, R_{\oplus}$ and an orbital ... More
Two planets around Kapteyn's star : a cold and a temperate super-Earth orbiting the nearest halo red-dwarfJun 03 2014Exoplanets of a few Earth masses can be now detected around nearby low-mass stars using Doppler spectroscopy. In this paper, we investigate the radial velocity variations of Kapteyn's star, which is both a sub-dwarf M-star and the nearest halo object ... More
Strict strategy-proofnessJul 31 2018A strictly strategy-proof mechanism is one that asks agents to use strictly dominant strategies. In the canonical one-dimensional mechanism design setting with private values, we show that strict strategy-proofness is equivalent to strict monotonicity ... More
Astrometric Light-Travel Time signature of sources in nonlinear motionNov 09 2005Context:Very precise planned space astrometric missions and recent improvements on imaging capabilities require a detailed review of the assumptions of classical astrometric modeling. Aims:We show that Light-Travel Time must be taken into account to model ... More
No evidence for activity correlations in the radial velocities of Kapteyn's starJun 30 2015Stellar activity may induce Doppler variability at the level of a few m/s which can then be confused by the Doppler signal of an exoplanet orbiting the star. To first order, linear correlations between radial velocity measurements and activity indices ... More
Water maser detections in southern candidates to post-AGB stars and Planetary NebulaeJun 16 2009Jun 21 2009We intended to study the incidence and characteristics of water masers in the envelopes of stars in the post-AGB and PN evolutionary stages. We have used the 64-m antenna in Parkes (Australia) to search for water maser emission at 22 GHz, towards a sample ... More
Statistical Analysis of Water Masers in Star-Forming Regions: Cepheus A and W75 NApr 14 2010We have done a statistical analysis of Very Long Baseline Array (VLBA) data of water masers in the star-forming regions (SFRs) Cepheus A and W75 N, using correlation functions to study the spatial clustering and Doppler-velocity distribution of these ... More
H$_2$O maser emission associated with the planetary nebula IRAS 16333$-$4807Jul 24 2014We present simultaneous observations of H$_2$O maser emission and radio continuum at 1.3 cm carried out with the Australia Telescope Compact Array towards two sources, IRAS 16333$-$4807 and IRAS 12405$-$6219, catalogued as planetary nebula (PN) candidates, ... More
Kinematics of the H2O masers at the centre of the PN K3-35Aug 28 2008We have studied the kinematics traced by the water masers located at the centre of the planetary nebula (PN) K3-35, using data from previous Very Large Array (VLA) observations. An analysis of the spatial distribution and line-of-sight velocities of the ... More
High-Resolution Observations in B1-IRS: ammonia, CCS and water masersJul 17 2004We present a study of the structure and dynamics of the star forming region B1-IRS (IRAS 03301+3057) using the properties of different molecules at high angular resolution (~4''). We have used VLA observations of NH3, CCS, and H2O masers at 1 cm. CCS ... More
Signatures of infall motions in the images of the molecular emission of G31 HMCNov 09 2013Although gravitational collapse is supposed to play an essential role in the star formation process, infall motions have been always elusive to detect. So far, only a few observational signatures have been commonly used to claim for the presence of infall. ... More