42 research outputs found
Not So Fast Kepler-1513: A Perturbing Planetary Interloper in the Exomoon Corridor
Transit Timing Variations (TTVs) can be induced by a range of physical
phenomena, including planet-planet interactions, planet-moon interactions, and
stellar activity. Recent work has shown that roughly half of moons would induce
fast TTVs with a short period in the range of two-to-four orbits of its host
planet around the star. An investigation of the Kepler TTV data in this period
range identified one primary target of interest, Kepler-1513 b. Kepler-1513 b
is a planet orbiting a late G-type dwarf at
AU. Using Kepler photometry, this initial analysis
showed that Kepler-1513 b's TTVs were consistent with a moon. Here, we report
photometric observations of two additional transits nearly a decade after the
last Kepler transit using both ground-based observations and space-based
photometry with TESS. These new transit observations introduce a previously
undetected long period TTV, in addition to the original short period TTV
signal. Using the complete transit dataset, we investigate whether a
non-transiting planet, a moon, or stellar activity could induce the observed
TTVs. We find that only a non-transiting perturbing planet can reproduce the
observed TTVs. We additionally perform transit origami on the Kepler
photometry, which independently applies pressure against a moon hypothesis.
Specifically, we find that Kepler-1513 b's TTVs are consistent with an exterior
non-transiting Saturn mass planet, Kepler-1513 c, on a wide orbit,
5 outside a 5:1 period ratio with Kepler-1513 b. This example
introduces a previously unidentified cause for planetary interlopers in the
exomoon corridor, namely an insufficient baseline of observations.Comment: 20 pages, 13 figures. Accepted to MNRAS. Code available at
https://github.com/dyahalomi/Kepler151
First results of the Kourovka Planet Search: discovery of transiting exoplanet candidates in the first three target fields
We present the first results of our search for transiting exoplanet
candidates as part of the Kourovka Planet Search (KPS) project. The primary
objective of the project is to search for new hot Jupiters which transit their
host stars, mainly in the Galactic plane, in the magnitude range of 11 to
14 mag. Our observations were performed with the telescope of the MASTER
robotic network, installed at the Kourovka astronomical observatory of the Ural
Federal University (Russia), and the Rowe-Ackermann Schmidt Astrograph,
installed at the private Acton Sky Portal Observatory (USA). As test
observations, we observed three celestial fields of size deg
during the period from 2012 to 2015. As a result, we discovered four transiting
exoplanet candidates among the 39000 stars of the input catalogue. In this
paper, we provide the description of the project and analyse additional
photometric, spectral, and speckle interferometric observations of the
discovered transiting exoplanet candidates. Three of the four transiting
exoplanet candidates are most likely astrophysical false positives, while the
nature of the fourth (most promising) candidate remains to be ascertained.
Also, we propose an alternative observing strategy that could increase the
project's exoplanet haul.Comment: 11 pages, 16 figures; Accepted for publication in Monthly Notices of
the Royal Astronomical Society 201
Benchmarking the power of amateur observatories for TTV exoplanets detection
This document is the Accepted Manuscript version of the following article: Roman v. Baluev, et al, ‘Benchmarking the power of amateur observatories for TTV exoplanets detection’, Monthly Notices of the Royal Astronomical Society, Vol. 450(3): 3101-3113, first published online 9 May 2015. The version of record is available at doi: https://doi.org/10.1093/mnras/stv788 © 2015 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society.We 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 Transit Database, public photometry from the literature, and some proprietary photometry privately supplied by other authors. Half of these lightcurves were obtained by amateurs. From this photometry we derive 306 transit timing measurements, as well as improved planetary transit parameters. Additionally, for 6 of these 10 stars we present a set of radial velocity measurements obtained from the spectra stored in the HARPS, HARPS-N, and SOPHIE archives using the HARPS-TERRA pipeline. Our analysis of these TTV and RV data did not reveal significant hints of additional orbiting bodies in almost all of the cases. In the WASP-4 case, we found hints of marginally significant TTV signals having amplitude 10-20 sec, although their parameters are model-dependent and uncertain, while radial velocities did not reveal statistically significant Doppler signals.Peer reviewe
Benchmarking the power of amateur observatories for TTV exoplanets detection
We perform an analysis of ~80 000 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 light curves from the Exoplanet Transit Database, public photometry from the literature, and some proprietary photometry privately supplied by other authors. Half of these light curves were obtained by amateurs. From this photometry we derive 306 transit timing measurements, as well as improved planetary transit parameters. Additionally, for 6 of these 10 stars we present a set of radial velocity measurements obtained from the spectra stored in the HARPS, HARPS-N and SOPHIE archives using the HARPS- TERRA pipeline. Our analysis of these transit timing and radial velocity data did not reveal significant hints of additional orbiting bodies in almost all of the cases. In the WASP-4 case, we found hints of marginally significant TTV signals having amplitude 10-20 s, although their parameters are model dependent and uncertain, while radial velocities did not reveal statistically significant Doppler signals.Facultad de Ciencias Astronómicas y GeofísicasInstituto de Astrofísica de La Plat
The First Post-Kepler Brightness Dips of KIC 8462852
We present a photometric detection of the first brightness dips of the unique variable star KIC 8462852 since the end of the Kepler space mission in 2013 May. Our regular photometric surveillance started in 2015 October, and a sequence of dipping began in 2017 May continuing on through the end of 2017, when the star was no longer visible from Earth. We distinguish four main 1%-2.5% dips, named Elsie, Celeste, Skara Brae, and Angkor, which persist on timescales from several days to weeks. Our main results so far are as follows: (i) there are no apparent changes of the stellar spectrum or polarization during the dips and (ii) the multiband photometry of the dips shows differential reddening favoring non-gray extinction. Therefore, our data are inconsistent with dip models that invoke optically thick material, but rather they are in-line with predictions for an occulter consisting primarily of ordinary dust, where much of the material must be optically thin with a size scale ≪1 μm, and may also be consistent with models invoking variations intrinsic to the stellar photosphere. Notably, our data do not place constraints on the color of the longer-term secular dimming, which may be caused by independent processes, or probe different regimes of a single process
KPS-1b: The First Transiting Exoplanet Discovered Using an Amateur Astronomer's Wide-field CCD Data
We report the discovery of the transiting hot Jupiter KPS-1b. This exoplanet orbits a V = 13.0 K1-type main sequence star every 1.7 days, has a mass of 1.090 (+0.086 -0.087) MJup and a radius of 1.03 (+0.13 -0.12) RJup. The discovery was made by the prototype Kourovka Planet Search (KPS) project, which used wide-field CCD data gathered by an amateur astronomer using readily available and relatively affordable equipment. Here we describe the equipment and observing technique used for the discovery of KPS-1b, its characterization with spectroscopic observations by the SOPHIE spectrograph and with high-precision photometry obtained with 1m class telescopes. We also outline the KPS project evolution into the Galactic Plane eXoplanet survey. The discovery of KPS-1b represents a new major step of the contribution of amateur astronomers to the burgeoning field of exoplanetology
KELT-24b: A 5MJ Planet on a 5.6day Well-aligned Orbit around the Young V = 8.3 F-star HD 93148
We present the discovery of KELT-24 b, a massive hot Jupiter orbiting a bright (V = 8.3 mag, K = 7.2 mag) young F-star with a period of 5.6 days. The host star, KELT-24 (HD 93148), has a Teff = 6509-+4950 K, a mass of M* = 1.460-+0.0590.055 Me, a radius of R* = 1.506 ± 0.022 Re, and an age of 0.78-+0.420.61 Gyr. Its planetary companion (KELT-24 b) has a radius of RP = 1.272 ± 0.021 RJ and a mass of MP = 5.18-+0.220.21 MJ, and from Doppler tomographic observations, we find that the planet’s orbit is well-aligned to its host star’s projected spin axis (l = 2.6-+3.65.1). The young age estimated for KELT-24 suggests that it only recently started to evolve from the zero-age main sequence. KELT-24 is the brightest star known to host a transiting giant planet with a period between 5 and 10 days. Although the circularization timescale is much longer than the age of the system, we do not detect a large eccentricity or significant misalignment that is expected from dynamical migration. The brightness of its host star and its moderate surface gravity make KELT-24b an intriguing target for detailed atmospheric characterization through spectroscopic emission measurements since it would bridge the current literature results that have primarily focused on lower mass hot Jupiters and a few brown dwarfs