- ID:
- ivo://CDS.VizieR/J/A+A/488/361
- Title:
- Mars Express astrometric observations of Phobos
- Short Name:
- J/A+A/488/361
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- New astrometric measurements for Phobos are reported on the basis of 69 SRC (Super Resolution Channel) images obtained during 28 Mars Express Phobos flybys executed between 2004 and 2007. The measurements have been made using a newly developed technique which involves positional measurements of surface control points and verification of camera pointing by background stars. The astrometric positions are in excellent agreement with currently available Phobos orbit models. However, we find remaining systematic offsets of 1.5-2.6km, with Phobos ahead of the predicted position along its track. Our observations will be a basis for further improvements in the Phobos ephemeris. The methods we have developed will be useful for astrometric tracking of planetary or asteroidal targets and spacecraft optical navigation in future planetary missions.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/614/A15
- Title:
- Mars Express astrometric obs. of Martian moons
- Short Name:
- J/A+A/614/A15
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Both Martian moons, Phobos and Deimos, have been observed during several imaging campaigns by the SRC on Mars Express. Several tens of images are obtained during mutual event observations - when the Martian moons are both observed or together with another solar system body. These observations provide new opportunities to determine the bodies' positions in their orbits. A method was sought to automate the observation of the positions of the imaged bodies. Within one image sequence a similarly accurate localization of the objects in all images should be possible. Shape models of Phobos and Deimos are applied to simulate the appearance of the bodies in the images. Matching the illuminated simulation against the observation provides a reliable determination of the bodies' location within the image. To enhance the matching confidence several corrections need to be applied to the simulation to closely reconstruct the observation. In total 884 relative positions between the different objects are provided.
- ID:
- ivo://CDS.VizieR/J/A+A/612/A57
- Title:
- MASCARA-2 b (HD185603) light curves and spectra
- Short Name:
- J/A+A/612/A57
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this paper we present MASCARA-2 b, a hot Jupiter transiting the m_V_=7.6 A2 star HD 185603. Since early 2015, MASCARA has taken more than 1.6 million flux measurements of the star, corresponding to a total of almost 3000 hours of observations, revealing a periodic dimming in the flux with a depth of 1.3%. Photometric follow-up observations were performed with the NITES and IAC80 telescopes and spectroscopic measurements were obtained with the Hertzsprung SONG telescope. We find MASCARA-2 b orbits HD 185603 with a period of 3.474119^+0.000005^_-0.000006_ days at a distance of 0.057+/-0.006AU, has a radius of 1.83+/-0.07R_J_ and place a 99 % upper limit on the mass of <17M_J_. HD 185603 is a rapidly rotating early-type star with an effective temperature of 8980^+90^_-130_K and a mass and radius of 1.89^+0.06^_-0.05_M_sun_, 1.60+/-0.06R_sun_, respectively. Contrary to most other hot Jupiters transiting early-type stars, the projected planet orbital axis and stellar spin axis are found to be aligned with {lambda}=0.6+/-4{deg}. The brightness of the host star and the high equilibrium temperature, 2260+/-50K, of MASCARA-2 b make it a suitable target for atmospheric studies from the ground and space. Of particular interest is the detection of TiO, which has recently been detected in the similarly hot planets WASP-33 b and WASP-19 b.
- ID:
- ivo://CDS.VizieR/J/ApJ/709/535
- Title:
- Masses and radii of eclipsing binaries
- Short Name:
- J/ApJ/709/535
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The currently favored method for estimating radii and other parameters of transiting-planet host stars is to match theoretical models to observations of the stellar mean density {rho}_*_, the effective temperature T_eff_, and the composition parameter [Z]. This explicitly model-dependent approach is based on readily available observations, and results in small formal errors. Its performance will be central to the reliability of results from ground-based transit surveys such as TrES, HAT, and SuperWASP, as well as to the space-borne missions MOST, CoRoT, and Kepler. Here, I use two calibration samples of stars (eclipsing binaries (EBs) and stars for which asteroseismic analyses are available) having well-determined masses and radii to estimate the accuracy and systematic errors inherent in the {rho}_*_ method. When matching to the Yonsei-Yale stellar evolution models, I find the most important systematic error results from selection bias favoring rapidly rotating (hence probably magnetically active) stars among the EB sample. If unaccounted for, this bias leads to a mass-dependent underestimate of stellar radii by as much as 4% for stars of 0.4M_{sun}_, decreasing to zero for masses above about 1.4M_{sun}_. Relative errors in estimated stellar masses are three times larger than those in radii.
- ID:
- ivo://CDS.VizieR/J/A+A/527/A140
- Title:
- Mass limits on substellar companions
- Short Name:
- J/A+A/527/A140
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The recently completed re-reduction of the Hipparcos data by van Leeuwen (2007, Astrophys. Space Library 350) makes it possible to search for the astrometric signatures of planets and brown dwarfs known from radial velocity surveys in the improved Hipparcos intermediate astrometric data. Our aim is to put more significant constraints on the orbital parameters which cannot be derived from radial velocities alone, i.e. the inclination and the longitude of the ascending node, than was possible before. The determination of the inclination in particular allows to calculate an unambiguous companion mass, rather than the lower mass limit which can be obtained from radial velocity measurements.
- ID:
- ivo://CDS.VizieR/J/ApJ/831/64
- Title:
- Mass-metallicity relation for giant planets
- Short Name:
- J/ApJ/831/64
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Exoplanet discoveries of recent years have provided a great deal of new data for studying the bulk compositions of giant planets. Here we identify 47 transiting giant planets (20 M_{\Earth}_ < M < 20 M_J_) whose stellar insolations are low enough (F_*_ < 2 x 10^8^ erg s^-1^ cm^-2^, or roughly T_eff_ < 1000) that they are not affected by the hot-Jupiter radius inflation mechanism(s). We compute a set of new thermal and structural evolution models and use these models in comparison with properties of the 47 transiting planets (mass, radius, age) to determine their heavy element masses. A clear correlation emerges between the planetary heavy element mass M_z_ and the total planet mass, approximately of the form M_z_\propto\sqrtM. This finding is consistent with the core-accretion model of planet formation. We also study how stellar metallicity [Fe/H] affects planetary metal-enrichment and find a weaker correlation than has previously been reported from studies with smaller sample sizes. We confirm a strong relationship between the planetary metal-enrichment relative to the parent star Z_planet_/Z_star_ and the planetary mass, but see no relation in Z_planet_/Z_star_ with planet orbital properties or stellar mass. The large heavy element masses of many planets (>50 M_{\Earth}_) suggest significant amounts of heavy elements in H/He envelopes, rather than cores, such that metal-enriched giant planet atmospheres should be the rule. We also discuss a model of core-accretion planet formation in a one-dimensional disk and show that it agrees well with our derived relation between mass and Z_planet_/Z_star_.
- ID:
- ivo://CDS.VizieR/J/ApJ/834/17
- Title:
- Mass & radius of planets, moons, low mass stars
- Short Name:
- J/ApJ/834/17
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Mass and radius are two of the most fundamental properties of an astronomical object. Increasingly, new planet discoveries are being announced with a measurement of one of these quantities, but not both. This has led to a growing need to forecast the missing quantity using the other, especially when predicting the detectability of certain follow-up observations. We present an unbiased forecasting model built upon a probabilistic mass-radius relation conditioned on a sample of 316 well-constrained objects. Our publicly available code, Forecaster, accounts for observational errors, hyper-parameter uncertainties, and the intrinsic dispersions observed in the calibration sample. By conditioning our model on a sample spanning dwarf planets to late-type stars, Forecaster can predict the mass (or radius) from the radius (or mass) for objects covering nine orders of magnitude in mass. Classification is naturally performed by our model, which uses four classes we label as Terran worlds, Neptunian worlds, Jovian worlds, and stars. Our classification identifies dwarf planets as merely low-mass Terrans (like the Earth) and brown dwarfs as merely high-mass Jovians (like Jupiter). We detect a transition in the mass-radius relation at 2.0_-0.6_^+0.7^M_{Earth}_, which we associate with the divide between solid, Terran worlds and Neptunian worlds. This independent analysis adds further weight to the emerging consensus that rocky super-Earths represent a narrower region of parameter space than originally thought. Effectively, then, the Earth is the super-Earth we have been looking for.
- ID:
- ivo://CDS.VizieR/J/ApJ/825/19
- Title:
- Mass-radius relationship for planets with Rp<4
- Short Name:
- J/ApJ/825/19
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Kepler Mission has discovered thousands of planets with radii <4R_{earth}_, paving the way for the first statistical studies of the dynamics, formation, and evolution of these sub-Neptunes and super-Earths. Planetary masses are an important physical property for these studies, and yet the vast majority of Kepler planet candidates do not have theirs measured. A key concern is therefore how to map the measured radii to mass estimates in this Earth-to-Neptune size range where there are no Solar System analogs. Previous works have derived deterministic, one-to-one relationships between radius and mass. However, if these planets span a range of compositions as expected, then an intrinsic scatter about this relationship must exist in the population. Here we present the first probabilistic mass-radius relationship (M-R relation) evaluated within a Bayesian framework, which both quantifies this intrinsic dispersion and the uncertainties on the M-R relation parameters. We analyze how the results depend on the radius range of the sample, and on how the masses were measured. Assuming that the M-R relation can be described as a power law with a dispersion that is constant and normally distributed, we find that M/M_{earth}_=2.7(R/R_{earth}_)^1.3^, a scatter in mass of 1.9M_{earth}_, and a mass constraint to physically plausible densities, is the "best-fit" probabilistic M-R relation for the sample of RV-measured transiting sub-Neptunes (R_pl_<4R_{earth}_). More broadly, this work provides a framework for further analyses of the M-R relation and its probable dependencies on period and stellar properties.
- ID:
- ivo://CDS.VizieR/J/A+A/602/A88
- Title:
- 5 M dwarfs radial velocity curves
- Short Name:
- J/A+A/602/A88
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Low mass stars are currently the best targets for searches for rocky planets in the habitable zone of their host star. Over the last 13 years, precise radial velocities measured with the HARPS spectrograph have identified over a dozen super-Earths and Earth-mass planets (msini<=10M_{sun}_) around M dwarfs, with a well understood selection function. This well defined sample informs on their frequency of occurrence and on the distribution of their orbital parameters, and therefore already constrains our understanding of planetary formation. The subset of these low-mass planets that were found within the habitable zone of their host star also provide prized targets for future atmospheric biomarkers searches. We are working to extend this planetary sample to lower masses and longer periods through dense and long-term monitoring of the radial velocity of a small M dwarf sample. We obtained large numbers of HARPS spectra for the M dwarfs GJ 3138, GJ 3323, GJ 273, GJ 628 and GJ 3293, from which we derived radial velocities (RVs) and spectroscopic activity indicators. We searched them for variabilities, periodicities, Keplerian modulations and correlations, and attribute the radial-velocity variations to combinations of planetary companions and stellar activity. We detect 12 planets, of which 9 are new with masses ranging from 1.17 to 10.5M_{sun}_. Those planets have relatively short orbital periods (P<40d), except two of them with periods of 217.6 and 257.8 days. Among these systems, GJ 273 harbor two planets with masses close to the one of the Earth. With a distance of 3.8 parsec only, GJ 273 is the second nearest known planetary system - after Proxima Centauri - with a planet orbiting the circumstellar habitable zone.
- ID:
- ivo://CDS.VizieR/J/A+A/562/A108
- Title:
- 150MHz emission from exoplanets
- Short Name:
- J/A+A/562/A108
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The ongoing radio continuum TIFR GMRT Sky Survey (TGSS) using the Giant Metrewave Radio Telescope (GMRT) at 150MHz offers an unprecedented opportunity to undertake a fairly deep search for low-frequency radio emission from nearby extrasolar planets. Currently TGSS images are available for a little over a steradian, encompassing 175 confirmed exoplanetary systems. We have searched for their radio counterparts in the TGSS (150MHz), supplemented with a search in the NRAO VLA Sky Survey (NVSS) and the VLA FIRST survey at 1.4GHz. For 171 planetary systems, we find no evidence of radio emission in the TGSS maps, placing a 3{sigma} upper limit between 8.7mJy and 136mJy (median ~24.8mJy) at 150MHz.
