28 research outputs found
A system of three transiting super-Earths in a cool dwarf star
We present the detection of three super-Earths transiting the cool star
LP415-17, monitored by K2 mission in its 13th campaign. High resolution spectra
obtained with HARPS-N/TNG showed that the star is a mid-late K dwarf. Using
spectral synthesis models we infer its effective temperature, surface gravity
and metallicity and subse- quently determined from evolutionary models a
stellar radius of 0.58 R Sun. The planets have radii of 1.8, 2.6 and 1.9 R
Earth and orbital periods of 6.34, 13.85 and 40.72 days. High resolution images
discard any significant contamination by an intervening star in the line of
sight. The orbit of the furthest planet has radius of 0.18 AU, close to the
inner edge of the habitable zone. The system is suitable to improve our
understanding of formation and dynamical evolution of super-Earth systems in
the rocky - gaseous threshold, their atmospheres, internal structure,
composition and interactions with host stars.Comment: Accepted for publication in MNRAS Letter
SHALOS: Statistical Herschel-ATLAS lensed objects selection
Context. The statistical analysis of large sample of strong lensing events can be a powerful tool to extract astrophysical or cosmological valuable information. Their selection using submillimetre galaxies has been demonstrated to be very effective with more than ∼200 proposed candidates in the case of Herschel-ATLAS data and several tens in the case of the South Pole Telescope. However, the number of confirmed events is still relatively low, i.e. a few tens, mostly because of the lengthy observational validation process on individual events. Aims. In this work we propose a new methodology with a statistical selection approach to increase by a factor of ∼5 the number of such events within the Herschel-ATLAS data set. Although the methodology can be applied to address several selection problems, it has particular benefits in the case of the identification of strongly lensed galaxies: objectivity, minimal initial constrains in the main parameter space, and preservation of statistical properties. Methods. The proposed methodology is based on the Bhattacharyya distance as a measure of the similarity between probability distributions of properties of two different cross-matched galaxies. The particular implementation for the aim of this work is called SHALOS and it combines the information of four different properties of the pair of galaxies: angular separation, luminosity percentile, redshift, and the ratio of the optical to the submillimetre flux densities. Results. The SHALOS method provides a ranked list of strongly lensed galaxies. The number of candidates within ∼340 deg2 of the Herschel-ATLAS surveyed area for the final associated probability, Ptot > 0.7, is 447 and they have an estimated mean amplification factor of 3.12 for a halo with a typical cluster mass. Additional statistical properties of the SHALOS candidates, as the correlation function or the source number counts, are in agreement with previous results indicating the statistical lensing nature of the selected sampleJGN acknowledges financial from the Spanish MINECO for a “Ramon y Cajal” fellowship (RYC2013-13256). DH, FA, and LT acknowledge financial support from the I+D
2015 project AYA2015-64508-P (MINECO, FEDER)
CARMENES input catalogue of M dwarfs IV. New rotation periods from photometric time series
Aims. The main goal of this work is to measure rotation periods of the M-type
dwarf stars being observed by the CARMENES exoplanet survey to help distinguish
radial-velocity signals produced by magnetic activity from those produced by
exoplanets. Rotation periods are also fundamental for a detailed study of the
relation between activity and rotation in late-type stars. Methods. We look for
significant periodic signals in 622 photometric time series of 337 bright,
nearby M dwarfs obtained by long-time baseline, automated surveys (MEarth,
ASAS, SuperWASP, NSVS, Catalina, ASAS-SN, K2, and HATNet) and for 20 stars
which we obtained with four 0.2-0.8 m telescopes at high geographical
latitudes. Results. We present 142 rotation periods (73 new) from 0.12 d to 133
d and ten long-term activity cycles (six new) from 3.0 a to 11.5 a. We compare
our determinations with those in the existing literature; we investigate the
distribution of P rot in the CARMENES input catalogue,the amplitude of
photometric variability, and their relation to vsin i and pEW(Halfa); and we
identify three very active stars with new rotation periods between 0.34 d and
23.6 d.Comment: 34 pages, 43 figures, 2 appendix table
Modelling the hypnotic patient response in general anaesthesia using intelligent models
International Conference on Computational Intelligence in Security for Information Systems (CISIS 2016)(9th, 2016, San Sebastian, Spain
First on-sky results of a neural network based tomographic reconstructor: Carmen on Canary
International audienc
First on-sky results of a neural network based tomographic reconstructor: Carmen on Canary
International audienc