- ID:
- ivo://CDS.VizieR/J/ApJ/582/1123
- Title:
- Search for transiting extrasolar planets
- Short Name:
- J/ApJ/582/1123
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Planet transit searches promise to be the next breakthrough for extrasolar planet detection and will bring the characterization of short-period planets into a new era. Every transiting planet discovered will have a measured radius, which will provide constraints on planet composition, evolution, and migration history. Together with radial velocity measurements, the absolute mass of every transiting planet will be determined. In this paper we discuss the design considerations of the Extrasolar Planet Occultation Research (EXPLORE) project, a series of transiting planet searches using 4-m class telescopes to continuously monitor a single field of stars in the Galactic plane in each ~2 week observing campaign.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/AJ/152/181
- Title:
- SETI observations of exoplanets with the ATA
- Short Name:
- J/AJ/152/181
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report radio SETI observations on a large number of known exoplanets and other nearby star systems using the Allen Telescope Array (ATA). Observations were made over about 19000hr from 2009 May to 2015 December. This search focused on narrowband radio signals from a set totaling 9293 stars, including 2015 exoplanet stars and Kepler objects of interest and an additional 65 whose planets may be close to their habitable zones. The ATA observations were made using multiple synthesized beams and an anticoincidence filter to help identify terrestrial radio interference. Stars were observed over frequencies from 1 to 9GHz in multiple bands that avoid strong terrestrial communication frequencies. Data were processed in near-real time for narrowband (0.7-100Hz) continuous and pulsed signals with transmitter/receiver relative accelerations from -0.3 to 0.3m/s^2^. A total of 1.9x10^8^ unique signals requiring immediate follow-up were detected in observations covering more than 8x10^6^ star-MHz. We detected no persistent signals from extraterrestrial technology exceeding our frequency-dependent sensitivity threshold of 180-310x10^-26^W/m^2^.
- ID:
- ivo://CDS.VizieR/J/MNRAS/448/1044
- Title:
- Simulation data for 50 planetary model systems
- Short Name:
- J/MNRAS/448/1044
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We describe the long-term evolution of compact systems of terrestrial planets, using a set of simulations that match the statistical properties of the observed exoplanet distribution. The evolution is driven by tidal dissipation in the planetary interiors, but the systems evolve as a whole due to secular gravitational interactions. We find that, for Earth-like dissipation levels, planetary orbits can be circularized out to periods ~100 d, an order of magnitude larger than is possible for single planets. The resulting distribution of eccentricities is a qualitative match to that inferred from transit timing variations, with a minority of non-zero eccentricities maintained by particular secular configurations. The coupling of the tidal and secular processes enhance the inward migration of the innermost planets in these systems, and can drive them to short orbital periods. Resonant interactions of both the mean motion and secular variety are observed, although the interactions are not strong enough to drive systemic instability in most cases. However, we demonstrate that these systems can easily be driven unstable if coupled to giant planets on longer period orbits.
- ID:
- ivo://CDS.VizieR/J/A+A/559/A62
- Title:
- Simulations of dust aggregates through collisions
- Short Name:
- J/A+A/559/A62
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Collisional growth of dust aggregates is an essential process to form planetesimals in protoplanetary disks, but disruption through high-velocity collisions (disruption barrier) could prohibit the dust growth. Mass transfer through highly different-sized collisions has been suggested to be a way to circumvent the disruption barrier. We examine how the collisional growth efficiency of dust aggregates at different impact parameters depends on the size and the mass-ratio of colliding aggregates. We use an N-body code to numerically simulate the collisions of different-sized aggregates. Our results show that large values of the impact parameter are important and the growth efficiency averaged over the impact parameter does not depend on the aggregate size although the growth efficiency for nearly head-on collisions increases with size. We also find that the averaged growth efficiency tends to increase with increasing the mass-ratio of colliding aggregates. However, the critical collision velocity, above which the growth efficiency becomes negative, does not strongly depend on the mass-ratio. These results indicate icy dust can grow through high-velocity offset collisions at several tens of m/s, the maximum collision velocity experienced in protoplanetary disks, whereas it is still difficult for silicate dust to grow in protoplanetary disks.
- ID:
- ivo://CDS.VizieR/J/A+A/586/A75
- Title:
- Simulations of hot gas planets atmospheres
- Short Name:
- J/A+A/586/A75
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Absorption of high-energy radiation in planetary thermospheres is generally believed to lead to the formation of planetary winds. The resulting mass-loss rates can affect the evolution, particularly of small gas planets. We present 1D, spherically symmetric hydrodynamic simulations of the escaping atmospheres of 18 hot gas planets in the solar neighborhood. Our sample only includes strongly irradiated planets, whose expanded atmospheres may be detectable via transit spectroscopy using current instrumentation. The simulations were performed with the PLUTO-CLOUDY interface, which couples a detailed photoionization and plasma simulation code with a general MHD code. We study the thermospheric escape and derive improved estimates for the planetary mass-loss rates. Our simulations reproduce the temperature-pressure profile measured via sodium D absorption in HD 189733 b, but show still unexplained differences in the case of HD 209458 b. In contrast to general assumptions, we find that the gravitationally more tightly bound thermospheres of massive and compact planets, such as HAT-P-2 b are hydrodynamically stable. Compact planets dispose of the radiative energy input through hydrogen Ly alpha and free-free emission. Radiative cooling is also important in HD 189733 b, but it decreases toward smaller planets like GJ 436 b. Computing the planetary Ly alpha absorption and emission signals from the simulations, we find that the strong and cool winds of smaller planets mainly cause strong Ly alpha absorption but little emission. Compact and massive planets with hot, stable thermospheres cause small absorption signals but are strong Ly{alpha} emitters, possibly detectable with the current instrumentation. The absorption and emission signals provide a possible distinction between these two classes of thermospheres in hot gas planets. According to our results, WASP-80 and GJ 3470 are currently the most promising targets for observational follow-up aimed at detecting atmospheric Ly{alpha} absorption signals.
- ID:
- ivo://CDS.VizieR/J/ApJ/786/33
- Title:
- Simulations of the late stage of planet formation
- Short Name:
- J/ApJ/786/33
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Models of planet formation have shown that giant planets have a large impact on the number, masses, and orbits of terrestrial planets that form. In addition, they play an important role in delivering volatiles from material that formed exterior to the snow line (the region in the disk beyond which water ice can condense) to the inner region of the disk where terrestrial planets can maintain liquid water on their surfaces. We present simulations of the late stages of terrestrial planet formation from a disk of protoplanets around a solar-type star and we include a massive planet (from 1 M_{earth}_ to 1 M_J_) in Jupiter's orbit at ~5.2 AU in all but one set of simulations. Two initial disk models are examined with the same mass distribution and total initial water content, but with different distributions of water content. We compare the accretion rates and final water mass fraction of the planets that form. Remarkably, all of the planets that formed in our simulations without giant planets were water-rich, showing that giant planet companions are not required to deliver volatiles to terrestrial planets in the habitable zone. In contrast, an outer planet at least several times the mass of Earth may be needed to clear distant regions of debris truncating the epoch of frequent large impacts. Observations of exoplanets from radial velocity surveys suggest that outer Jupiter-like planets may be scarce, therefore, the results presented here suggest that there may be more habitable planets residing in our galaxy than previously thought.
- ID:
- ivo://CDS.VizieR/J/AJ/136/267
- Title:
- Six occultations of the exoplanet TrES-3
- Short Name:
- J/AJ/136/267
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present photometry of the exoplanet host star TrES-3 spanning six occultations (secondary eclipses) of its giant planet. No flux decrements were detected, leading to 99%-confidence upper limits on the planet-to-star flux ratio of 2.4x10^-4^, 5.0x10^-4^, and 8.6x10^-4^ in the i-, z-, and R-bands respectively. The corresponding upper limits on the planet's geometric albedo are 0.30, 0.62, and 1.07. The upper limit in the i-band rules out the presence of highly reflective clouds, and is only a factor of 2-3 above the predicted level of thermal radiation from the planet.
- ID:
- ivo://CDS.VizieR/J/AJ/134/1707
- Title:
- Six transits of exoplanet HAT-P-1b
- Short Name:
- J/AJ/134/1707
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present photometry of the G0 star HAT-P-1 during six transits of its close-in giant planet, and we refine the estimates of the system parameters. Relative to Jupiter's properties, HAT-P-1b is 1.20+/-0.05 times larger, and its surface gravity is 2.7+/-0.2 times weaker. Although it remains the case that HAT-P-1b is among the least dense of the known sample of transiting exoplanets, its properties are in accord with previously published models of strongly irradiated, coreless, solar-composition giant planets. The times of the transits have a typical accuracy of 1 minute and do not depart significantly from a constant period.
- ID:
- ivo://CDS.VizieR/J/AJ/137/4911
- Title:
- Six transits of the exoplanet XO-2b
- Short Name:
- J/AJ/137/4911
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present photometry of six transits of the exoplanet XO-2b. By combining the light-curve analysis with theoretical isochrones to determine the stellar properties, we find the planetary radius to be 0.996^+0.031^_-0.018_R_Jup_ and the planetary mass to be 0.565+/-0.054M_Jup_. These results are consistent with those reported previously, and are also consistent with theoretical models for gas giant planets. The midtransit times are accurate to within 1 minute and are consistent with a constant period. However, the period we derive differs by 2.5{sigma } from the previously published period. More data are needed to tell whether the period is actually variable (as it would be in the presence of an additional body) or if the timing errors have been underestimated.
- ID:
- ivo://CDS.VizieR/J/A+A/508/1509
- Title:
- Sky maps for hot Jupiters
- Short Name:
- J/A+A/508/1509
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The findings of more than 350 extrasolar planets, most of them nontransiting Hot Jupiters, have revealed correlations between the metallicity of the main-sequence (MS) host stars and planetary incidence. This connection can be used to calculate the planet formation probability around other stars, not yet known to have planetary companions. Numerous wide-field surveys have recently been initiated, aiming at the transit detection of extrasolar planets in front of their host stars. Depending on instrumental properties and the planetary distribution probability, the promising transit locations on the celestial plane will differ among these surveys. We want to locate the promising spots for transit surveys on the celestial plane and strive for absolute values of the expected number of transits in general. Our study will also clarify the impact of instrumental properties such as pixel size, field of view (FOV), and magnitude range on the detection probability. We used data of the Tycho catalog for ~1 million objects to locate all the stars with 0^m^~<m_V_~<11.5^m^ on the celestial plane. We took several empirical relations between the parameters listed in the Tycho catalog, such as distance to Earth, m_V_, and (B-V), and those parameters needed to account for the probability of a star to host an observable, transiting exoplanet. The empirical relations between stellar metallicity and planet occurrence combined with geometrical considerations were used to yield transit probabilities for the MS stars in the Tycho catalog. Magnitude variations in the FOV were simulated to test whether this fluctuations would be detected by BEST, XO, SuperWASP and HATNet.