Fewer giants planets are found around M dwarfs than around more massive stars, and this dependence of planetary characteristics on the mass of the central star is an important observational diagnostic of planetary formation theories. In part to improve on those statistics, we are monitoring the radial velocities of nearby M dwarfs with the HARPS spectrograph on the ESO 3.6m telescope. We present here the detection of giant planets around two nearby M0 dwarfs: planets, with minimum masses of respectively 5 Jupiter masses and 1 Saturn mass, orbit around Gl 676A and HIP 12961.
We study the distribution of gas pressure and entropy in eight groups of galaxies belonging to the ROSAT All-Sky Survey/Center for Astrophysics Loose Systems (RASSCALS, Cat. <J/ApJ/534/114>). We use archival and proprietary XMM-Newton observations, supplementing the X-ray data with redshifts derived from the literature; we also list 125 new redshifts measured with the Gemini North telescope.
The Gaia-ESO Survey (GES) is a large public spectroscopic survey at the European Southern Observatory Very LargeTelescope. A key aim is to provide precise radial velocities (RVs) and projected equatorial velocities (vsini) for representative samples of Galactic stars, which will complement information obtained by the Gaia astrometry satellite. We present an analysis to empirically quantify the size and distribution of uncertainties in RV and vsini using spectra from repeated exposures of the same stars. We show that the uncertainties vary as simple scaling functions of signal-to-noise ratio (S/N) and vsini, that the uncertainties become larger with increasing photospheric temperature, but that the dependence on stellar gravity, metallicity and age is weak. The underlying uncertainty distributions have extended tails that are better represented by Students t-distributions than by normal distributions. Parametrised results are provided, which enable estimates of the RV precision for almost all GES measurements, and estimates of the vsini precision for stars in young clusters, as a function of S/N, vsini and stellar temperature. The precision of individual high S/N GES RV measurements is 0.22-0.26km/s, dependent on instrumental configuration.
We present a stellar dynamical estimate of the black hole (BH) mass in the Seyfert 1 galaxy, NGC 4151. We analyze ground-based spectroscopy as well as imaging data from the ground and space, and we construct three-integral axisymmetric models in order to constrain the BH mass and mass-to-light ratio.
A compilation of proper motions, radial velocities, and apparent magnitudes of B and A stars is combined with the absolute magnitudes and colour excesses from the "Catalogue of estimated astrophysical parameters" by Philip and Egret (at. V/14).
The KONUS instruments were flown on pairs of Venera spacecraft. Veneras 11/12 were launched in September 1978; bursts were recorded through January 1980. Veneras 13/14 were launched in November 1981 and were operational through approximately March 1983. The Veneras were interplanetary spacecraft, which flew to Venus, and thus each spacecraft had whole sky coverage for most of its mission. This is a service provided by NASA HEASARC .
Venus Express Cleaned High-Resolution 128 Hz Magnetic Field Data
Collection
Short Name:
VEX-HIGH-MAG
Date:
15 Dec 2022 19:30:21
Publisher:
Planetary Data System
Description:
This collection contains Venus Express cleaned high-resolution (128
Hz) magnetic field data acquired by the fluxgate magnetometer
gradiometer onboard the Venus Express spacecraft. The data are
expressed in Venus Solar Orbital (VSO) coordinates and
Radial-East-North coordinates.
Water vapor and sulfur compounds are key species in the photochemistry of Venus mesosphere. These species, together with mesospheric temperatures, exhibit drastic temporal variations, both on short timescales (diurnal and day-to-day) as well on long timescales, far from being understood. We targeted CO, SO, H_2_O and SO_2_ transitions in the submillimeter range using the Atacama Large Millimeter Array (ALMA) to study their spatial and temporal variations. Four sets of observations were acquired on different dates in November 2011 during the first ALMA Early Science observation Cycle 0. Venus angular diameter was about 11" with an illumination factor of 92%, so that mostly the day side of the planet was mapped. Assuming a nominal CO abundance profile, we retrieved vertical temperature profiles over the entire disk as a function of latitude and local time. Temperature profiles were later used to retrieve SO, SO_2_, and H_2_O. We used H_2_O as a tracer for water assuming a D/H enrichment of 200 times the terrestrial value. We derived 3-D maps of mesospheric temperatures in the altitude range 70-105km. SO, SO_2_, and H_2_O are characterized by a negligible abundance below ~85km followed by an increase with altitude in the upper mesosphere. Disk-averaged SO abundances present a maximum mixing ratio of 15.0+/-3.1ppb on November 26 followed the next day by a minimum value of 9.9+/-1.2ppb. Due to a very low S/N, SO_2_ could only be derived from the disk-averaged spectrum on the first day of observation revealing an abundance of 16.5+/-4.6ppb. We found a SO_2_/SO ratio of 1.5+/-0.4. Global maps of SO reveal strong variations both with latitude and local time and from day to day with abundance ranging from <1 to 15ppb. H_2_O disk-averages retrievals reveal a steady decrease from November 14 to 27, with the abundance varying from 3.6+/-0.6ppm on the first day to 2.9+/-0.7ppm on the last day. H_2_O maps reveal a slightly higher abundance on the evening side compared to the morning side and a strong depletion between the first and the second day of observation.