HAT-P-6b: A Hot Jupiter transiting a bright F star

In the ongoing HATNet survey we have detected a giant planet, with radius 1.33 +/- 0.06 RJup and mass 1.06 +/- 0.12 MJup, transiting the bright (V = 10.5) star GSC 03239-00992. The planet is in a circular orbit with period 3.852985 +/- 0.000005 days and mid-transit epoch 2,454,035.67575 +/- 0.00028 (HJD). The parent star is a late F star with mass 1.29 +/- 0.06 Msun, radius 1.46 +/- 0.06 Rsun, Teff ~ 6570 +/- 80 K, [Fe=H] = -0.13 +/- 0.08 and age ~ 2.3+/-^{0.5}_{0.7}Gy. With this radius and mass, HAT-P-6b has somewhat larger radius than theoretically expected. We describe the observations and their analysis to determine physical properties of the HAT-P-6 system, and briefly discuss some implications of this finding.Comment: Accepted for publication in ApJL, 5 pages, minor changes compared to V

Periodic variability of spotted M dwarfs in WTS

This is an Open Access article distributed under the terms of the Creative Commons Attribution License 2.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.We present an analysis of the photometric variability of M dwarfs in the WFCAM Transit Survey, selected from spectral types inferred by their WTS and SDSS colours, with periods detected using a Lomb-Scargle Periodogram Analisys. We estimate population membership of these objects from their tangential velocities and photometric parralaxes. Examples of M dwarfs with variable light curve morphologuies are found. We discuss possible causes for this and make use of models of spotted stars in our interpretation of the results

HAT-P-5b: A Jupiter-like hot Jupiter Transiting a Bright Star

We report the discovery of a planet transiting a moderately bright (V = 12.00) G star, with an orbital period of 2.788491 +/-0.000025 days. From the transit light curve we determine that the radius of the planet is Rp = 1.257 +/- 0.053 RJup. HAT-P-5b has a mass of Mp = 1.06 +/- 0.11 MJup, similar to the average mass of previously-known transiting exoplanets, and a density of rho = 0.66 +/- 0.11 g cm^-3 . We find that the center of transit is Tc = 2,454,241.77663 +/- 0.00022 (HJD), and the total transit duration is 0.1217 +/- 0.0012 days.Comment: 5 pages, submitted to APJ

A sensitivity analysis of the WFCAM Transit Survey for short-period giant planets around M dwarfs

The WFCAM Transit Survey (WTS) is a near-infrared transit survey running on the United Kingdom Infrared Telescope (UKIRT), designed to discover planets around M dwarfs. The WTS acts as a poor-seeing backup programme for the telescope, and represents the first dedicated wide-field near-infrared transit survey. In this paper we describe the observing strategy of the WTS and the processing of the data to generate lightcurves. We describe the basic properties of our photometric data, and measure our sensitivity based on 950 observations. We show that the photometry reaches a precision of ~4mmag for the brightest unsaturated stars in lightcurves spanning almost 3 years. Optical (SDSS griz) and near-infrared (UKIRT ZYJHK) photometry is used to classify the target sample of 4600 M dwarfs with J magnitudes in the range 11-17. Most have spectral-types in the range M0-M2. We conduct Monte Carlo transit injection and detection simulations for short period (<10 day) Jupiter- and Neptune-sized planets to characterize the sensitivity of the survey. We investigate the recovery rate as a function of period and magnitude for 4 hypothetical star-planet cases: M0-2+Jupiter, M2-4+Jupiter, M0-2+Neptune, M2-4+Neptune. We find that the WTS lightcurves are very sensitive to the presence of Jupiter-sized short-period transiting planets around M dwarfs. Hot Neptunes produce a much weaker signal and suffer a correspondingly smaller recovery fraction. Neptunes can only be reliably recovered with the correct period around the rather small sample (~100) of the latest M dwarfs (M4-M9) in the WTS. The non-detection of a hot-Jupiter around an M dwarf by the WFCAM Transit Survey allows us to place an upper limit of 1.7-2.0 per cent (at 95 per cent confidence) on the planet occurrence rate.Comment: 20 pages, 13 figures; accepted for publication in MNRA

sbpy: A Python module for small-body planetary astronomy

Peer reviewe

The Type la Supernova 2001V in NGC 3987

CCD photometry of the type Ia SN 2001V occured in the edge-on spiral galaxy NGC 3987 is presented. The observations made through Johnson-Cousins BVRI filters were collected from Feb. 24 (t = -8 days, with respect to B-maximum), up to May 5 (t = +62 days). The light curves are analyzed with the revised Multi-Colour Light Curve Shape (MLCS) method by fitting template vectors to the observed light curves simultaneously. The reddening of SN 2001V is estimated to be E(B-V)=0.05 mag, while the galactic component is E(B-V) = 0.02 mag, suggesting that part of the reddening may be due to the ISM in the host galaxy. The Delta parameter in MLCS converged to -0.47 mag, indicating that this SN was overluminous relative to the majority of Type Ia SNe. The inferred distance to its host galaxy, NGC 3987, is 74.5 \pm 5 Mpc, which is in good agreement with recently determined kinematic distances, based on radial velocity corrected for Virgo-infall and Hubble constant H_0 = 65 km/s/Mpc.Comment: 6 pages, 4 figures, accepted in Astronomy and Astrophysic

Independent confirmation and refined parameters of the hot Jupiter XO-5b

We present HATNet observations of XO-5b, confirming its planetary nature based on evidence beyond that described in the announcement of Burke et al. (2008), namely, the lack of significant correlation between spectral bisector variations and orbital phase. In addition, using extensive spectroscopic measurements spanning multiple seasons, we investigate the relatively large scatter in the spectral line bisectors. We also examine possible blended stellar configurations (hierarchical triples, chance alignments) that can mimic the planet signals, and we are able to show that none are consistent with the sum of all the data. The analysis of the S activity index shows no significant stellar activity. Our results for the planet parameters are consistent with values in Burke et al. (2008), and we refine both the stellar and planetary parameters using our data. XO-5b orbits a slightly evolved, late G type star with mass M_s = 0.88 +/- 0.03, radius R_s = 1.08 +/- 0.04, and metallicity close to solar. The planetary mass and radius are M_p = 1.059 +/- 0.028 M_Jup and R_p = 1.109 +/- 0.050 R_Jup, respectively, corresponding to a mean density of 0.96 -0.11 +0.14 g/cm^3. The ephemeris for the orbit is P = 4.187757 +/- 0.000011, E= 2454552.67168 +/- 0.00029 (BJD) with transit duration of 0.1307 +/- 0.0013 d. By measuring four individual transit centers, we found no signs for transit timing variations. The planet XO-5b is notable for its anomalously high Safronov number, and has a high surface gravity when compared to other transiting exoplanets with similar period.Comment: Accepted for publication in ApJ, 8 pages in emulateapj styl

Early Ultraviolet Observations of Type IIn Supernovae Constrain the Asphericity of Their Circumstellar Material

© 2020. The American Astronomical Society. All rights reserved.. We present a survey of the early evolution of 12 Type IIn supernovae (SNe IIn) at ultraviolet and visible light wavelengths. We use this survey to constrain the geometry of the circumstellar material (CSM) surrounding SN IIn explosions, which may shed light on their progenitor diversity. In order to distinguish between aspherical and spherical CSM, we estimate the blackbody radius temporal evolution of the SNe IIn of our sample, following the method introduced by Soumagnac et al. We find that higher-luminosity objects tend to show evidence for aspherical CSM. Depending on whether this correlation is due to physical reasons or to some selection bias, we derive a lower limit between 35% and 66% for the fraction of SNe IIn showing evidence for aspherical CSM. This result suggests that asphericity of the CSM surrounding SNe IIn is common - consistent with data from resolved images of stars undergoing considerable mass loss. It should be taken into account for more realistic modeling of these events