In this paper, we derive the fundamental properties of 1SWASPJ011351.29+314909.7 (J0113+31), a metal-poor (-0.40 +/- 0.04 dex), eclipsing binary in an eccentric orbit (~0.3) with an orbital period of ~14.277 d. Eclipsing M dwarfs orbiting solar-type
stars (EBLMs), like J0113+31, have been identified from WASP light curves and follow-up spectroscopy in the course of the transiting planet search. We present the first binary of the EBLM sample to be fully analysed, and thus, define here the methodology. The primary component with a mass of 0.945 +/- 0.045 Msun has a large radius (1.378 +/- 0.058 Rsun) indicating that the system is quite old, ~9.5 Gyr. The M-dwarf secondary mass of 0.186 +/- 0.010 Msun and radius of 0.209 +/- 0.011 Rsun are fully consistent with stellar evolutionary models. However, from the near-infrared secondary eclipse light curve, the M dwarf is found to have an effective temperature of 3922 +/- 42 K, which is ~600 K hotter than predicted by theoretical models. We discuss different scenarios to explain this temperature discrepancy. The case of J0113+31 for which we can measure mass, radius, temperature and metallicity, highlights the importance of deriving mass, radius and temperature as a function of metallicity for M dwarfs to better understand the lowest mass stars. The EBLM Project will define the relationship between mass, radius, temperature and metallicity for M dwarfs providing important empirical constraints at the bottom of the main sequence.
We report the discovery of two transiting hot Jupiters, WASP-65b (M_pl = 1.55 +/- 0.16 M_J; R_pl = 1.11 +/- 0.06 R_J), and WASP-75b (M_pl = 1.07 +/- 0.05 M_J; R_pl = 1.27 +/- 0.05 R_J). They orbit their host star every 2.311, and 2.484 days, respecti
vely. The planet host WASP-65 is a G6 star (T_eff = 5600 K, [Fe/H] = -0.07 +/- 0.07, age > 8 Gyr); WASP-75 is an F9 star (T_eff = 6100 K, [Fe/H] = 0.07 +/- 0.09, age of 3 Gyr). WASP-65b is one of the densest known exoplanets in the mass range 0.1 and 2.0 M_J (rho_pl = 1.13 +/- 0.08 rho_J), a mass range where a large fraction of planets are found to be inflated with respect to theoretical planet models. WASP-65b is one of only a handful of planets with masses of around 1.5 M_J, a mass regime surprisingly underrepresented among the currently known hot Jupiters. The radius of Jupiter-mass WASP-75b is slightly inflated (< 10%) as compared to theoretical planet models with no core, and has a density similar to that of Saturn (rho_pl = 0.52 +/- 0.06 rho_J).
We present the fundamental stellar and planetary properties of the transiting planetary system WASP-13 within the framework of the Homogeneous Study of Transiting Systems (HoSTS). HoSTS aims to derive the fundamental stellar (Teff, [Fe/H], Mstar, Rst
ar), and planetary (Mpl, Rpl, Teq) physical properties of known transiting planets using a consistent methodology and homogeneous high-quality dataset. Four spectral analysis techniques are independently applied to a Keck+HIRES spectrum of WASP-13 considering two distinct cases: unconstrained parameters, and constrained log g from transit light curves. We check the derived stellar temperature against that from a different temperature diagnostic based on an INT+IDS H{alpha} spectrum. The four unconstrained analyses render results that are in good agreement, and provide an improvement of 50% in the precision of Teff, and of 85% in [Fe/H] with respect to the WASP-13 discovery paper. The planetary parameters are then derived via the Monte-Carlo-Markov-Chain modeling of the radial velocity and light curves, in iteration with stellar evolutionary models to derive realistic uncertainties. WASP-13 (1.187 +- 0.065 Msun; 1.574 +- 0.048 Rsun) hosts a Saturn-mass, transiting planet (0.500 +- 0.037 MJup; 1.407 +- 0.052 RJup), and is at the end of its main-sequence lifetime (4-5.5 Gyr). Our analysis of WASP-13 showcases that both a detailed stellar characterization, and transit modeling are necessary to well determine the fundamental properties of planetary systems, which are paramount in identifying and determining empirical relationships between transiting planets and their hosts.
Parenago 1802, a member of the ~1 Myr Orion Nebula Cluster, is a double-lined, detached eclipsing binary in a 4.674 d orbit, with equal-mass components (M_2/M_1 = 0.985 pm 0.029). Here we present extensive VIcJHKs light curves spanning ~15 yr, as wel
l as a Keck/HIRES optical spectrum. The light curves evince a third light source that is variable with a period of 0.73 d, and is also manifested in the high-resolution spectrum, strongly indicating the presence of a third star in the system, probably a rapidly rotating classical T Tauri star. We incorporate this third light into our radial velocity and light curve modeling of the eclipsing pair, measuring accurate masses (M_1 = 0.391 pm 0.032, M_2 = 0.385 pm 0.032 Modot), radii (R_1 = 1.73 pm 0.02, R_2 = 1.62 pm 0.02 Rodot), and temperature ratio (T_1/T_2 = 1.0924 pm 0.0017). Thus the radii of the eclipsing stars differ by 6.9 pm 0.8%, the temperatures differ by 9.2 pm 0.2%, and consequently the luminosities differ by 62 pm 3%, despite having masses equal to within 3%. This could be indicative of an age difference of ~3x10^5 yr between the two eclipsing stars, perhaps a vestige of the binary formation history. We find that the eclipsing pair is in an orbit that has not yet fully circularized, e = 0.0166 pm 0.003. In addition, we measure the rotation rate of the eclipsing stars to be 4.629 pm 0.006 d; they rotate slightly faster than their 4.674 d orbit. The non-zero eccentricity and super-synchronous rotation suggest that the eclipsing pair should be tidally interacting, so we calculate the tidal history of the system according to different tidal evolution theories. We find that tidal heating effects can explain the observed luminosity difference of the eclipsing pair, providing an alternative to the previously suggested age difference.
We present the JHKs light curves for the double-lined eclipsing binary 2MASS J05352184-0546085, in which both components are brown dwarfs. We analyze these light curves with the published Ic-band light curve and radial velocities to provide refined m
easurements of the systems physical parameters. The component masses and radii are here determined with an accuracy of ~6.5% and ~1.5%, respectively. We confirm the previous surprising finding that the primary brown dwarf has a cooler effective temperature than its companion. Next, we perform a detailed study of the variations in the out-of-eclipse phases of the light curves to ascertain the properties of any inhomogeneities on the surfaces of the brown dwarfs. Our analysis reveals two low-amplitude periodic signals, one attributable to the rotation of the primary (with a period of 3.293+/-0.001 d) and the other to that of the secondary (14.05+/-0.05 d). Finally, we explore the effects on the derived physical parameters of the system when spots are included in the modeling. The observed low-amplitude rotational modulations are well fit by cool spots covering a small fraction of their surfaces. To mimic the observed ~200 K suppression of the primarys temperature, our model requires that the primary possess a very large spot coverage fraction of ~65%. Altogether, a spot configuration in which the primary is heavily spotted while the secondary is lightly spotted can explain the apparent temperature reversal and can bring the temperatures of the brown dwarfs into agreement with the predictions of theoretical models.
K 3-35 is a planetary nebula (PN) where H2O maser emission has been detected, suggesting that it departed from the proto-PNe phase only some decades ago. Interferometric VLA observations of the OH 18 cm transitions in K~3-35 are presented.OH maser em
ission is detected in all four ground state lines (1612, 1665, 1667, and 1720 MHz). All the masers appear blueshifted with respect to the systemic velocity of the nebula and they have different spatial and kinematic distributions.The OH 1665 and 1720 MHz masers appear spatially coincident with the core of the nebula, while the OH 1612 and 1667 MHz ones exhibit a more extended distribution. We suggest that the 1665 and 1720 masers arise from a region close to the central star, possibly in a torus, while the 1612 and 1667 lines originate mainly from the extended northern lobe of the outflow. It is worth noting that the location and velocity of the OH 1720 MHz maser emission are very similar to those of the H2O masers (coinciding within 0.1 and ~2 km/s, respectively). We suggest that the pumping mechanism in the H2O masers could be produced by the same shock that is exciting the OH 1720 MHz transition. A high degree of circular polarization (>50%) was found to be present in some features of the 1612, 1665, and 1720 MHz emission.For the 1665 MHz transition at ~ +18 km/s the emission with left and right circular polarizations (LCP and RCP) coincide spatially within a region of ~0.03 in diameter.Assuming that these RCP and LCP 1665 features come from a Zeeman pair, we estimate a magnetic field of ~0.9 mG within 150 AU from the 1.3 cm continuum peak. This value is in agreement with a solar-type magnetic field associated with evolved stars.
We present observations of continuum (lambda = 0.7, 1.3, 3.6 and 18 cm) and OH maser (lambda = 18 cm) emission toward the young planetary nebula IRAS 17347-3139, which is one of the three planetary nebulae that are known to harbor water maser emissio
n. From the continuum observations we show that the ionized shell of IRAS 17347-3139 consists of two main structures: one extended (size ~1. 5) with bipolar morphology along PA=-30 degrees, elongated in the same direction as the lobes observed in the near-infrared images, and a central compact structure (size ~0. 25) elongated in the direction perpendicular to the bipolar axis, coinciding with the equatorial dark lane observed in the near-infrared images. Our image at 1.3 cm suggests the presence of dense walls in the ionized bipolar lobes. We estimate for the central compact structure a value of the electron density at least ~5 times higher than in the lobes. A high resolution image of this structure at 0.7 cm shows two peaks separated by about 0. 13 (corresponding to 100-780 AU, using a distance range of 0.8-6 kpc). This emission is interpreted as originating in an ionized equatorial torus-like structure, from whose edges the water maser emission might be arising. We have detected weak OH 1612 MHz maser emission at VLSR ~ -70 km/s associated with IRAS 17347-3139. We derive a 3 sigma upper limit of < 35% for the percentage of circularly polarized emission. Within our primary beam, we detected additional OH 1612 MHz maser emission in the LSR velocity ranges -5 to -24 and -90 to -123 km/s, associated with the sources 2MASS J17380406-3138387 and OH 356.65-0.15, respectively.
We have studied the kinematics traced by the water masers located at the centre of the planetary nebula (PN) K3-35, using data from previous Very Large Array (VLA) observations. An analysis of the spatial distribution and line-of-sight velocities of
the maser spots allows us to identify typical patterns of a rotating and expanding ring in the position-velocity diagrams, according to our kinematical model. We find that the distribution of the masers is compatible with tracing a circular ring with a ~0.021 arcsec (~100 AU) radius, observed with an inclination angle with respect to the line of sight of 55 degrees. We derive expansion and rotation velocities of 1.4 and 3.1 km/s, respectively. The orientation of the ring projected on the plane of the sky, at PA 158 degrees, is almost orthogonal to the direction of the innermost region of the jet observed in K3-35, suggesting the presence of a disc or torus that may be related to the collimation of the outflow.
Stars at the top of the asymptotic giant branch (AGB) can exhibit maser emission from molecules like SiO, H2O and OH. As the star evolves to the planetary nebula phase, mass-loss stops and ionization of the envelope begins, making the masers disappea
r progressively. The OH masers in PNe can be present in the envelope for periods of ~1000 years but the water masers can survive only hundreds of years. Then, water maser emission is not expected in planetary nebulae! We discuss the unambiguous detection of water maser emission in two planetary nebulae: K 3-35 and IRAS 17347-3139.
The bipolar morphology of the planetary nebula (PN) K 3-35 observed in radio-continuum images was modelled with 3D hydrodynamic simulations with the adaptive grid code yguazu-a. We find that the observed morphology of this PN can be reproduced consid
ering a precessing jet evolving in a dense AGB circumstellar medium, given by a mass loss rate dot{M}_{csm}=5x10^{-5}M_{odot}/yr and a terminal velocity v_{w}=10 km/s. Synthetic thermal radio-continuum maps were generated from numerical results for several frequencies. Comparing the maps and the total fluxes obtained from the simulations with the observational results, we find that a model of precessing dense jets, where each jet injects material into the surrounding CSM at a rate dot{M}_j=2.8x10^{-4} {M_{odot}/yr (equivalent to a density of 8x10^{4} {cm}^{-3}, a velocity of 1500 km/s, a precession period of 100 yr, and a semi-aperture precession angle of 20 degrees agrees well with the observations.
