We report the discovery and confirmation of a transiting circumbinary planet (PH1b) around KIC 4862625, an eclipsing binary in the Kepler field. The planet was discovered by volunteers searching the ...first six Quarters of publicly available Kepler data as part of the Planet Hunters citizen science project. Transits of the planet across the larger and brighter of the eclipsing stars are detectable by visual inspection every ~ 137 days, with seven transits identified in Quarters 1-11. The physical and orbital parameters of both the host stars and planet were obtained via a photometric-dynamical model, simultaneously fitting both the measured radial velocities and the Kepler light curve of KIC 4862625. The 6.18 + or - 0.17 R sub(+ in circle) planet orbits outside the 20 day orbit of an eclipsing binary consisting of an F dwarf (1.734 + or - 0.044 R sub(middot in circle), 1.528 + or - 0.087 M sub(middot in circle)) and M dwarf (0.378 + or - 0.023 R sub(middot in circle), 0.408 + or - 0.024 M sub(middot in circle)). For the planet, we find an upper mass limit of 169 M sub(+ in circle) (0.531 Jupiter masses) at the 99.7% confidence level. With a radius and mass less than that of Jupiter, PH1b is well within the planetary regime. Outside the planet's orbit, at ~ 1000 AU, a previously unknown visual binary has been identified that is likely bound to the planetary system, making this the first known case of a quadruple star system with a transiting planet.
Galaxy Zoo: CANDELS barred discs and bar fractions Simmons, B. D; Melvin, Thomas; Lintott, Chris ...
Monthly Notices of the Royal Astronomical Society,
12/2014, Letnik:
445, Številka:
4
Journal Article
Recenzirano
Odprti dostop
The formation of bars in disc galaxies is a tracer of the dynamical maturity of the population. Previous studies have found that the incidence of bars in discs decreases from the local Universe to z ...∼ 1, and by z > 1 simulations predict that bar features in dynamically mature discs should be extremely rare. Here, we report the discovery of strong barred structures in massive disc galaxies at z ∼ 1.5 in deep rest-frame optical images from the Cosmic Assembly Near-Infrared Deep Extragalactic Legacy Survey. From within a sample of 876 disc galaxies identified by visual classification in Galaxy Zoo, we identify 123 barred galaxies. Selecting a subsample within the same region of the evolving galaxy luminosity function (brighter than L*), we find that the bar fraction across the redshift range 0.5 ≤ z ≤ 2 (
$f_{{\rm bar}} = 10.7^{+6.3}_{-3.5}$
per cent after correcting for incompleteness) does not significantly evolve. We discuss the implications of this discovery in the context of existing simulations and our current understanding of the way disc galaxies have evolved over the last 11 billion years.
We report the discovery of one newly confirmed planet (P = 66.06 days, R sub(P) = 2.68 + or - 0.17 R sub(+ in circle)) and mass determinations of two previously validated Kepler planets, Kepler-289 b ...(P = 34.55 days, R sub(P) = 2.15 + or - 0.10 R sub(+ in circle)) and Kepler-289-c (P = 125.85 days, R sub(P) = 11.59 + or - 0.10 R sub(+ in circle)), through their transit timing variations (TTVs). We also exclude the possibility that these three planets reside in a 1:2:4 Laplace resonance. The outer planet has very deep (~ 1.3%), high signal-to-noise transits, which puts extremely tight constraints on its host star's stellar properties via Kepler's Third Law. The star PH3 is a young (~1 Gyr as determined by isochrones and gyrochronology), Sun-like star with M sub(*) = 1.08 + or - 0.02 M sub(middot in circle), R sub(*) = 1.00 + or - 0.02 R sub(middot in circle), and T sub(eff) = 5990 + or - 38 K. The middle planet's large TTV amplitude (~5 hr) resulted either in non-detections or inaccurate detections in previous searches. A strong chopping signal, a shorter period sinusoid in the TTVs, allows us to break the mass-eccentricity degeneracy and uniquely determine the masses of the inner, middle, and outer planets to be M = 7.3 + or - 6.8 M sub(+ in circle), 4.0 + or - 0.9 M sub(+ in circle), and M = 132 + or - 17 M sub(+ in circle), which we designate PH3 b, c, and d, respectively. Furthermore, the middle planet, PH3 c, has a relatively low density, rho = 1.2 + or - 0.3 g cm super(-3) for a planet of its mass, requiring a substantial H/He atmosphere of 2.1 sub(+0.8) super(-0.3)% by mass, and joins a growing population of low-mass, low-density planets.
We report the latest Planet Hunter results, including PH2 b, a Jupiter-size (R sub(PL) = 10.12 + or - 0.56 R sub(+ in circle)) planet orbiting in the habitable zone of a solar-type star. PH2 b was ...elevated from candidate status when a series of false-positive tests yielded a 99.9% confidence level that transit events detected around the star KIC 12735740 had a planetary origin. Planet Hunter volunteers have also discovered 42 new planet candidates in the Kepler public archive data, of which 33 have at least 3 transits recorded. Most of these transit candidates have orbital periods longer than 100 days and 20 are potentially located in the habitable zones of their host stars. Nine candidates were detected with only two transit events and the prospective periods are longer than 400 days. The photometric models suggest that these objects have radii that range between those of Neptune and Jupiter. These detections nearly double the number of gas-giant planet candidates orbiting at habitable-zone distances. We conducted spectroscopic observations for nine of the brighter targets to improve the stellar parameters and we obtained adaptive optics imaging for four of the stars to search for blended background or foreground stars that could confuse our photometric modeling. We present an iterative analysis method to derive the stellar and planet properties and uncertainties by combining the available spectroscopic parameters, stellar evolution models, and transiting light curve parameters, weighted by the measurement errors. Planet Hunters is a citizen science project that crowd sources the assessment of NASA Kepler light curves. The discovery of these 43 planet candidates demonstrates the success of citizen scientists at identifying planet candidates, even in longer period orbits with only two or three transit events.
The original Kepler mission observed and characterized over 2400 eclipsing binaries (EBs) in addition to its prolific exoplanet detections. Despite the mechanical malfunction and subsequent ...non-recovery of two reaction wheels used to stabilize the instrument, the Kepler satellite continues collecting data in its repurposed K2 mission surveying a series of fields along the ecliptic plane. Here, we present an analysis of the first full baseline K2 data release: the Campaign 0 data set. In the 7761 light curves we have identified a total of 207 EBs. Of these, 97 are new discoveries that were not previously identified. Our pixel-level analysis of these objects has also resulted in identification of several false positives (observed targets contaminated by neighbouring EBs), as well as the serendipitous discovery of two short-period exoplanet candidates. We provide catalogue cross-matched source identifications, orbital periods, morphologies and ephemerides for these eclipsing systems. We also describe the incorporation of the K2 sample into the Kepler Eclipsing Binary Catalog,
§
present spectroscopic follow-up observations for a limited selection of nine systems and discuss prospects for upcoming K2 campaigns.
ABSTRACT We present high-resolution observations of a sample of 75 K2 targets from Campaigns 1-3 using speckle interferometry on the Southern Astrophysical Research (SOAR) telescope and adaptive ...optics imaging at the Keck II telescope. The median SOAR I-band and Keck Ks-band detection limits at 1 ″ were Δ m I = 4.4 mag and Δ m K s = 6.1 mag, respectively. This sample includes 37 stars likely to host planets, 32 targets likely to be eclipsing binaries (EBs), and 6 other targets previously labeled as likely planetary false positives. We find nine likely physically bound companion stars within 3 ″ of three candidate transiting exoplanet host stars and six likely EBs. Six of the nine detected companions are new discoveries. One of these new discoveries, EPIC 206061524, is associated with a planet candidate. Among the EB candidates, companions were only found near the shortest period ones ( P < 3 days), which is in line with previous results showing high multiplicity near short-period binary stars. This high-resolution data, including both the detected companions and the limits on potential unseen companions, will be useful in future planet vetting and stellar multiplicity rate studies for planets and binaries.
We report the discovery of 14 new transiting planet candidates in the Kepler field from the Planet Hunters citizen science program. None of these candidates overlapped with Kepler Objects of Interest ...(KOIs) at the time of submission. We report the discovery of one more addition to the six planet candidate system around KOI-351, making it the only seven planet candidate system from Kepler. Additionally, KOI-351 bears some resemblance to our own solar system, with the inner five planets ranging from Earth to mini-Neptune radii and the outer planets being gas giants; however, this system is very compact, with all seven planet candidates orbiting lap1 AU from their host star. A Hill stability test and an orbital integration of the system shows that the system is stable. Furthermore, we significantly add to the population of long period transiting planets; periods range from 124 to 904 days, eight of them more than one Earth year long. Seven of these 14 candidates reside in their host star's habitable zone.
KIC 9406652 is a remarkable variable star in the Kepler field of view that shows both very rapid oscillations and long term outbursts in its light curve. We present an analysis of the light curve ...over quarters 1-15 and new spectroscopy that indicates that the object is a cataclysmic variable with an orbital period of 6.108 hr. However, an even stronger signal appears in the light curve periodogram for a shorter period of 5.753 hr, and we argue that this corresponds to the modulation of flux from the hot spot region in a tilted, precessing disk surrounding the white dwarf star. We present a preliminary orbital solution from radial velocity measurements of features from the accretion disk and the photosphere of the companion. We use a Doppler tomography algorithm to reconstruct the disk and companion spectra, and we also consider how these components contribute to the object's spectral energy distribution from ultraviolet to infrared wavelengths. This target offers us a remarkable opportunity to investigate disk processes during the high mass transfer stage of evolution in cataclysmic variables.
We present new planet candidates identified in NASA Kepler Quarter 2 public release data by volunteers engaged in the Planet Hunters citizen science project. The two candidates presented here survive ...checks for false positives, including examination of the pixel offset to constrain the possibility of a background eclipsing binary. The orbital periods of the planet candidates are 97.46 days (KIC 4552729) and 284.03 (KIC 10005758) days and the modeled planet radii are 5.3 and 3.8 R sub(+ in circle). The latter star has an additional known planet candidate with a radius of 5.05 R sub(+ in circle) and a period of 134.49 days, which was detected by the Kepler pipeline. The discovery of these candidates illustrates the value of massively distributed volunteer review of the Kepler database to recover candidates which were otherwise uncataloged.
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