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Register a new userA search for transiting planets in the $beta$ Pictoris system
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Added by
Matthew A. Kenworthy
Publication date
2018
fields
Physics
and research's language is
English
Authors
M. Mol Lous
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The bright $(V=3.86)$ star $beta$ Pictoris is a nearby young star with a debris disk and gas giant exoplanet, $beta$ Pictoris b, in a multi-decade orbit around it. Both the planets orbit and disk are almost edge-on to our line of sight. We carry out a search for any transiting planets in the $beta$ Pictoris system with orbits of less than 30 days that are coplanar with the planet $beta$ Pictoris b. We search for a planetary transit using data from the BRITE-Constellation nanosatellite BRITE-Heweliusz, analyzing the photometry using the Box-Fitting Least Squares Algorithm (BLS). The sensitivity of the method is verified by injection of artificial planetary transit signals using the Bad-Ass Transit Model cAlculatioN (BATMAN) code. No planet was found in the BRITE-Constellation data set. We rule out planets larger than 0.6 $mathrm{R_J}$ for periods of less than 5 days, larger than 0.75 $mathrm{R_J}$ for periods of less than 10 days, and larger than 1.05 $mathrm{R_J}$ for periods of less than 20 days.
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Photometry of stars from the K2 extension of NASAs Kepler mission is afflicted by systematic effects caused by small (few-pixel) drifts in the telescope pointing and other spacecraft issues. We present a method for searching K2 light curves for evidence of exoplanets by simultaneously fitting for these systematics and the transit signals of interest. This method is more computationally expensive than standard search algorithms but we demonstrate that it can be efficiently implemented and used to discover transit signals. We apply this method to the full Campaign 1 dataset and report a list of 36 planet candidates transiting 31 stars, along with an analysis of the pipeline performance and detection efficiency based on artificial signal injections and recoveries. For all planet candidates, we present posterior distributions on the properties of each system based strictly on the transit observables.
Exoplanetary science has reached a historic moment. The James Webb Space Telescope will be capable of probing the atmospheres of rocky planets, and perhaps even search for biologically produced gases. However this is contingent on identifying suitable targets before the end of the mission. A race therefore, is on, to find transiting planets with the most favorable properties, in time for the launch. Here, we describe a realistic opportunity to discover extremely favorable targets - rocky planets transiting nearby brown dwarfs - using the Spitzer Space Telescope as a survey instrument. Harnessing the continuous time coverage and the exquisite precision of Spitzer in a 5,400 hour campaign monitoring nearby brown dwarfs, we will detect a handful of planetary systems with planets as small as Mars. The survey we envision is a logical extension of the immense progress that has been realized in the field of exoplanets and a natural outcome of the exploration of the solar neighborhood to map where the nearest habitable rocky planets are located (as advocated by the 2010 Decadal Survey). Our program represents an essential step towards the atmospheric characterization of terrestrial planets and carries the compelling promise of studying the concept of habitability beyond Earth-like conditions. In addition, our photometric monitoring will provide invaluable observations of a large sample of nearby brown dwarfs situated close to the M/L transition. This is why, we also advocate an immediate public release of the survey data, to guarantee rapid progress on the planet search and provide a treasure trove of data for brown dwarf science.
We search for signs of falling evaporating bodies (FEBs, also known as exocomets) in photometric time series obtained for $beta$ Pictoris after fitting and removing its $delta$ Scuti type pulsation frequencies. Using photometric data obtained by the TESS satellite we determine the pulsational properties of the exoplanet host star $beta$ Pictoris through frequency analysis. We then prewhiten the 54 identified $delta$ Scuti p-modes and investigate the residual photometric time series for the presence of FEBs. We identify three distinct dipping events in the light curve of $beta$ Pictoris over a 105-day period. These dips have depths from 0.5 to 2 millimagnitudes and durations of up to 2 days for the largest dip. These dips are asymmetric in nature and are consistent with a model of an evaporating comet with an extended tail crossing the disk of the star. We present the first broadband detections of exocomets crossing the disk of $beta$ Pictoris, consistent with the predictions made 20 years earlier by Lecavelier Des Etangs et al. (1999). No periodic transits are seen in this time series. These observations confirm the spectroscopic detection of exocomets in Calcium H and K lines that have been seen in high resolution spectroscopy.
The Beta Pictoris Moving Group is a nearby stellar association of young (12Myr) co-moving stars including the classical debris disk star beta Pictoris. Due to their proximity and youth they are excellent targets when searching for submillimetre emission from cold, extended, dust components produced by collisions in Kuiper-Belt-like disks. They also allow an age independent study of debris disk properties as a function of other stellar parameters. We observed 7 infrared-excess stars in the Beta Pictoris Moving Group with the LABOCA bolometer array, operating at a central wavelength of 870 micron at the 12-m submillimetre telescope APEX. The main emission at these wavelengths comes from large, cold dust grains, which constitute the main part of the total dust mass, and hence, for an optically thin case, make better estimates on the total dust mass than earlier infrared observations. Fitting the spectral energy distribution with combined optical and infrared photometry gives information on the temperature and radial extent of the disk. From our sample, beta Pic, HD181327, and HD172555 were detected with at least 3-sigma certainty, while all others are below 2-sigma and considered non-detections. The image of beta Pic shows an offset flux density peak located near the south-west extension of the disk, similar to the one previously found by SCUBA at the JCMT. We present SED fits for detected sources and give an upper limit on the dust mass for undetected ones. We find a mean fractional dust luminosity f_dust=11x10^{-4} at t=12Myr, which together with recent data at 100Myr suggests an f_dust propto t^{-alpha} decline of the emitting dust, with alpha > 0.8.
Because the planets of a system form in a flattened disk, they are expected to share similar orbital inclinations at the end of their formation. The high-precision photometric monitoring of stars known to host a transiting planet could thus reveal the transits of one or more other planets. We investigate here the potential of this approach for the M dwarf GJ 1214 that hosts a transiting super-Earth. For this system, we infer the transit probabilities as a function of orbital periods. Using Monte-Carlo simulations we address both the cases for fully coplanar and for non-coplanar orbits, with three different choices of inclinations distribution for the non-coplanar case. GJ 1214 reveals to be a very promising target for the considered approach. Because of its small size, a ground-based photometric monitoring of this star could detect the transit of a habitable planet as small as the Earth, while a space-based monitoring could detect any transiting habitable planet down to the size of Mars. The mass measurement of such a small planet would be out of reach for current facilities, but we emphasize that a planet mass would not be needed to confirm the planetary nature of the transiting object. Furthermore, the radius measurement combined with theoretical arguments would help us to constrain the structure of the planet.
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