* Astronomy

Blobrana · L

RE: Extrasolar Planets

Blobrana · L

Tiny versions of Jupiter, Saturn and our sun have been discovered about 5,000 light years away, according to astronomers.
The astronomers, including a team at Ohio State University, were able to see the two planets and star by using a technique called gravitational microlensing, which occurs when an object such as a planet or star crosses between another star and Earth.

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Blobrana · L

Earth-like planets may have formed around most of the Milky Ways Sun-like stars, according to research that shortens the odds on the discovery of extra-terrestrial life.
Observations using Nasas Spitzer Space Telescope have found that at least 20 per cent and perhaps as many as 60 per cent of our galaxys Sun-like stars are good candidates for having rocky planets of the sort that can harbour life.

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Blobrana · L

Rocky planets, possibly with conditions suitable for life, may be more common than previously thought in our galaxy, a study has found.
New evidence suggests more than half the Sun-like stars in the Milky Way could have similar planetary systems.

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Blobrana · L

Astronomers have discovered that terrestrial planets might form around many, if not most, of the nearby sun-like stars in our galaxy. These new results suggest that worlds with potential for life might be more common than we thought.
University of Arizona, Tucson, astronomer Michael Meyer and his colleagues used NASA's Spitzer Space Telescope to determine whether planetary systems like ours are common or rare in our Milky Way galaxy. They found that at least 20 percent, and possibly as many as 60 percent, of stars similar to the sun are candidates for forming rocky planets.

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Blobrana · L

Title: New Solutions for the Planetary Dynamics in HD160691 using a Newtonian Model and Latest Data
Authors: D. Short, G. Windmiller, J. A. Orosz

In this letter we present several new three and four-planet solutions based on the most current available radial velocity data for HD160691 (mu Ara). These solutions are optimised using the Planetary Orbit Fitting Process (POFP) which is programmed and executed in MATLAB. POFP is based on a full integration of the system's multiple-body Newtonian equations of motion and on a multi level optimisation utilizing a variety of algorithms. The POFP solutions are presented in the context of the Keplerian-based solutions already appearing in the literature which we have reproduced here for comparison. The different solutions and their properties are compared over all data sets separately and combined. The new solutions do not seem to exhibit instabilities and are both co-planar and three-dimensional. We also provide a comparative prediction of the published and new solutions showing their diversion in the near future. In the short term, this projection will allow to choose between the variety of solutions as further observations are made.

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Blobrana · L

Title: The University of New South Wales Extrasolar Planet Search: a catalogue of variable stars from fields observed 2004--2007
Authors: J.L. Christiansen, A. Derekas, L.L. Kiss, M.C.B. Ashley, S.J. Curran, D.W. Hamacher, M.G. Hidas, M.R. Thompson, J.K. Webb, T.B. Young

We present a new catalogue of variable stars compiled from data taken for the University of New South Wales Extrasolar Planet Search. From 2004 October to 2007 May, 25 target fields were each observed for 1-4 months, resulting in ~87000 high precision light curves with 1600-4400 data points. We have extracted a total of 850 variable light curves, 659 of which do not have a counterpart in either the General Catalogue of Variable Stars, the New Suspected Variables catalogue or the All Sky Automated Survey southern variable star catalogue. The catalogue is detailed here, and includes 142 Algol-type eclipsing binaries, 23 beta Lyrae-type eclipsing binaries, 218 contact eclipsing binaries, 53 RR Lyrae stars, 26 Cepheid stars, 13 rotationally variable active stars, 153 uncategorised pulsating stars with periods <10 d, including delta Scuti stars, and 222 long period variables with variability on timescales of >10 d. As a general application of variable stars discovered by extrasolar planet transit search projects, we discuss several astrophysical problems which could benefit from carefully selected samples of bright variables. These include: (i) the quest for contact binaries with the smallest mass ratio, which could be used to test theories of binary mergers; (ii) detached eclipsing binaries with pre-main-sequence components, which are important test objects for calibrating stellar evolutionary models; and (iii) RR Lyrae-type pulsating stars exhibiting the Blazhko-effect, which is one of the last great mysteries of pulsating star research.

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Blobrana · L

Title: Migration and Final Location of Hot Super Earths in the Presence of Gas Giants
Authors: Ji-Lin Zhou, Douglas N.C. Lin

Based on the conventional sequential-accretion paradigm, we have proposed that, during the migration of first-born gas giants outside the orbits of planetary embryos, super Earth planets will form inside the 2:1 resonance location by sweeping of mean motion resonances (Zhou et al. 2005). In this paper, we study the subsequent evolution of a super Earth (m_1) under the effects of tidal dissipation and perturbation from a first-born gas giant (m_2) in an outside orbit. Secular perturbation and mean motion resonances (especially 2:1 and 5:2 resonances) between m_1 and m_2 excite the eccentricity of m_1, which causes the migration of m_1 and results in a hot super Earth. The calculated final location of the hot super Earth is independent of the tidal energy dissipation factor Q'. The study of migration history of a Hot Super Earth is useful to reveal its Q' value and to predict its final location in the presence of one or more hot gas giants. When this investigation is applied to the GJ876 system, it correctly reproduces the observed location of GJ876d around 0.02AU.

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Blobrana · L

HD 74156

Blobrana · L

RE: Extrasolar Planets