The Random Transiter – EPIC 249706694/HD 139139 Rappaport, S.; Vanderburg, A.; Omohundro, M.R. ...
Monthly notices of the Royal Astronomical Society,
09/2019, Letnik:
488, Številka:
2
Journal Article
Recenzirano
Odprti dostop
We have identified a star, EPIC 249706694 (HD 139139), that was observed during K2 Campaign 15 with the Kepler extended mission that appears to exhibit 28 transit-like events over the course of the ...87-day observation. The unusual aspect of these dips, all but two of which have depths of 200 ± 80 ppm, is that they exhibit no periodicity, and their arrival times could just as well have been produced by a random number generator. We show that no more than four of the events can be part of a periodic sequence. We have done a number of data quality tests to ascertain that these dips are of astrophysical origin, and while we cannot be absolutely certain that this is so, they have all the hallmarks of astrophysical variability on one of two possible host stars (a likely bound pair) in the photometric aperture. We explore a number of ideas for the origin of these dips, including actual planet transits due to multiple or dust emitting planets, anomalously large TTVs, S- and P-type transits in binary systems, a collection of dust-emitting asteroids, ‘dipper-star’ activity, and short-lived starspots. All transit scenarios that we have been able to conjure up appear to fail, while the intrinsic stellar variability hypothesis would be novel and untested.
We report the discovery of four transiting extrasolar planets (HAT-P-34b-HAT-P-37b) with masses ranging from 1.05 to 3.33 M sub(J) and periods from 1.33 to 5.45 days. These planets orbit relatively ...bright F and G dwarf stars (from V = 10.16 to V = 13.2). Of particular interest is HAT-P-34b which is moderately massive (3.33 M sub(J)), has a high eccentricity of e = 0.441 + or - 0.032 at a period of P = 5.452654 + or - 0.000016 days, and shows hints of an outer component. The other three planets have properties that are typical of hot Jupiters.
Abstract
We have discovered a young M star of mass 0.16 M⊙ and radius 0.63 R⊙, likely in the Upper Sco Association, that exhibits only a single 80 per cent deep occultation of 1-d duration. The star ...has frequent flares and a low-amplitude rotational modulation, but is otherwise quiet over 160 d of cumulative observation during K2 campaigns C2 and C15. We discuss how such a deep eclipse is not possible by one star crossing another in any binary or higher order stellar system in which no mass transfer has occurred. The two possible explanations we are left with are (1) orbiting dust or small particles (e.g. a disc bound to a smaller orbiting body, or unbound dust that emanates from such a body); or (2) a transient accretion event of dusty material near the corotation radius of the star. In either case, the time between such occultation events must be longer than ∼80 d. We model a possible orbiting occulter both as a uniform elliptically shaped surface (e.g. an inclined circular disc) and as a ‘dust sheet’ with a gradient of optical depth behind its leading edge. The required masses in such dust features are then ≳3 × 1019 g and ≳1019 g, for the two cases, respectively.
Abstract
We report the discovery of HAT-P-67b, which is a hot-Saturn transiting a rapidly rotating F-subgiant. HAT-P-67b has a radius of
, and orbites a
,
host star in a ∼4.81 day period orbit. We ...place an upper limit on the mass of the planet via radial velocity measurements to be
, and a lower limit of
by limitations on Roche lobe overflow. Despite being a subgiant, the host star still exhibits relatively rapid rotation, with a projected rotational velocity of
, which makes it difficult to precisely determine the mass of the planet using radial velocities. We validated HAT-P-67b via two Doppler tomographic detections of the planetary transit, which eliminate potential eclipsing binary blend scenarios. The Doppler tomographic observations also confirm that HAT-P-67b has an orbit that is aligned to within 12°, in projection, with the spin of its host star. HAT-P-67b receives strong UV irradiation and is among one of the lowest density planets known, which makes it a good candidate for future UV transit observations in the search for an extended hydrogen exosphere.
The purpose of this study was to investigate the way in which anthropometric and fitness measures vary by class year before and after a Division I female field hockey competitive season. ...Anthropometric (mass and percent body fat) and fitness measures (vertical jump and Yo-Yo Intermittent Recovery Test 1 (Yo-Yo IR1) distance) were collected on 16 athletes (mean ± SD: age = 19.5 ± 0.9 years) before and after a competitive season. Class year, based on the athlete’s year in college, was used to group athletes in the study. Body mass, vertical jump height, and Yo-Yo IR1 distance all increased pre to post season (p < 0.05). First-year athletes had a significantly lower body mass, vertical jump height and Yo-Yo IR1 distance compared to other class years across the testing period (p < 0.05). Post season levels for first-years were lower than both pre and post season levels for sophomore or junior athletes. Team mean vertical jump increased 8.9%, with all but two athletes improving. Team mean Yo-Yo IR1 distance increased 16.4%. Athlete training over the course of the study was designed to improve on field playing performance and training was not directly select to improve measures in the study; therefore, the potential success of integrating fitness, speed, and strength development into technical training sessions is indicated. Coaches should be aware that first-year athletes may not be at the same level of conditioning as sophomores and juniors. Coaches should work specifically with the first-year athletes during the season to monitor their fitness levels.
We report the characterization of two planet candidates detected by the Transiting Exoplanet Survey Satellite (TESS), TOI-1199 b and TOI-1273 b, with periods of 3.7 and 4.6 days, respectively. ...Follow-up observations for both targets, which include several ground-based light curves, confirmed the transit events. High-precision radial velocities from the SOPHIE spectrograph revealed signals at the expected frequencies and phases of the transiting candidates and allowed mass determinations with a precision of 8.4% and 6.7% for TOI-1199 b and TOI-1273 b, respectively. The planetary and orbital parameters were derived from a joint analysis of the radial velocities and photometric data. We find that the planets have masses of 0.239 ± 0.020 M J and 0.222 ± 0.015 M J and radii of 0.938 ± 0.025 R J and 0.99 ± 0.22 R J , respectively. The grazing transit of TOI-1273 b translates to a larger uncertainty in its radius, and hence also in its bulk density, compared to TOI-1199 b. The inferred bulk densities of 0.358 ± 0.041 g cm −3 and 0.28 ± 0.11 g cm −3 are among the lowest known for exoplanets in this mass range, which, considering the brightness of the host stars ( V ≈11 mag), render them particularly amenable to atmospheric characterization via the transit spectroscopy technique. The better constraints on the parameters of TOI-1199 b provide a transmission spectroscopy metric of 134 ± 17, making it the better suited of the two planets for atmospheric studies.
We present the discovery of two new transiting extrasolar planet candidates identified as TOI-1296.01 and TOI-1298.01 by the Transiting Exoplanet Survey Satellite (TESS). The planetary nature of ...these candidates has been secured with the SOPHIE high-precision spectrograph through the measurement of the companion’s mass with the radial velocity method. Both planets are similar to Saturn in mass and have similar orbital periods of a few days. They, however, show discrepant radii and therefore different densities. The radius discrepancy might be explained by the different levels of irradiation by the host stars. The subgiant star TOI-1296 hosts a low-density planet with 1.2
R
Jup
while the less luminous, lower-size star TOI-1298 hosts a much denser planet with a 0.84
R
Jup
radius, resulting in bulk densities of 0.198 and 0.743 g cm
−3
, respectively.In addition, both stars are strongly enriched in heavy elements, having metallicities of +0.44 and +0.49 dex, respectively. The planet masses and orbital periods are 0.298 ± 0.039
M
Jup
and 3.9443715 ± 5.8 ± 10
−6
days for TOI-1296b, and 0.356 ± 0.032
M
Jup
and 4.537164 ± 1.2 ± 10
−5
days for TOI-1298b. The mass measurements have a relative precision of better than 13%.
Abstract
We report the discovery and characterization of seven transiting exoplanets from the HATNet survey. The planets, which are hot Jupiters and Saturns transiting bright Sun-like stars, include: ...HAT-P-58b (with mass
M
p
= 0.37
M
J
, radius
R
p
= 1.33
R
J
, and orbital period
P
= 4.0138 days), HAT-P-59b (
M
p
= 1.54
M
J
,
R
p
= 1.12
R
J
,
P
= 4.1420 days), HAT-P-60b (
M
p
= 0.57
M
J
,
R
p
= 1.63
R
J
,
P
= 4.7948 days), HAT-P-61b (
M
p
= 1.06
M
J
,
R
p
= 0.90
R
J
,
P
= 1.9023 days), HAT-P-62b (
M
p
= 0.76
M
J
,
R
p
= 1.07
R
J
,
P
= 2.6453 days), HAT-P-63b (
M
p
= 0.61
M
J
,
R
p
= 1.12
R
J
,
P
= 3.3777 days), and HAT-P-64b (
M
p
= 0.58
M
J
,
R
p
= 1.70
R
J
,
P
= 4.0072 days). The typical errors on these quantities are 0.06
M
J
, 0.03
R
J
, and 0.2 s, respectively. We also provide accurate stellar parameters for each of the host stars. With
V
= 9.710 ± 0.050 mag, HAT-P-60 is an especially bright transiting planet host, and an excellent target for additional follow-up observations. With
R
p
= 1.703 ± 0.070
R
J
, HAT-P-64b is a highly inflated hot Jupiter around a star nearing the end of its main-sequence lifetime, and is among the largest known planets. Five of the seven systems have long-cadence observations by TESS which are included in the analysis. Of particular note is HAT-P-59 (TOI-1826.01) which is within the northern continuous viewing zone of the TESS mission, and HAT-P-60, which is the TESS candidate TOI-1580.01.
Abstract
White dwarf WD 1145+017 is orbited by several clouds of dust, possibly emanating from actively disintegrating bodies. These dust clouds reveal themselves through deep, broad, and evolving ...transits in the star's light curve. Here, we report two epochs of multiwavelength photometric observations of WD 1145+017, including several filters in the optical, Ks and 4.5 μm bands in 2016 and 2017. The observed transit depths are different at these wavelengths. However, after correcting for excess dust emission at Ks and 4.5 μm, we find the transit depths for the white dwarf itself are the same at all wavelengths, at least to within the observational uncertainties of ∼5–10 per cent. From this surprising result, and under the assumption of low optical depth dust clouds, we conclude that there is a deficit of small particles (with radii s ≲ 1.5 μm) in the transiting material. We propose a model wherein only large particles can survive the high equilibrium temperature environment corresponding to 4.5 h orbital periods around WD 1145+017, while small particles sublimate rapidly. In addition, we evaluate dust models that are permitted by our measurements of infrared emission.
PDF
