447 research outputs found
Detection and measurement of planetary systems with GAIA
We use detailed numerical simulations and the Andromedae,
planetary system as a template to evaluate the capability of the ESA
Cornerstone Mission GAIA in detecting and measuring multiple planets around
solar-type stars in the neighborhood of the Solar System. For the outer two
planets of the Andromedae, system, GAIA high-precision global
astrometric measurements would provide estimates of the full set of orbital
elements and masses accurate to better than 1--10%, and would be capable of
addressing the coplanarity issue by determining the true geometry of the system
with uncertainties of order of a few degrees. Finally, we discuss the
generalization to a variety of configurations of potential planetary systems in
the solar neighborhood for which GAIA could provide accurate measurements of
unique value for the science of extra-solar planets.Comment: 4 pages, 2 pictures, accepted for publication in A&A Letter
Narrow-Angle Astrometry with the Space Interferometry Mission: The Search for Extra-Solar Planets. II. Detection and Characterization of Planetary Systems
(Abridged) The probability of detecting additional companions is essentially
unchanged with respect to the single-planet configurations, but after fitting
and subtraction of orbits with astrometric signal-to-noise ratio
the false detection rates can be enhanced by up to a
factor 2; the periodogram approach results in robust multiple-planet detection
for systems with periods shorter than the SIM mission length, even at low
values of , while the least squares technique combined with
Fourier series expansions is arguably preferable in the long-period regime. The
accuracy on multiple-planet orbit reconstruction and mass determination suffers
a typical degradation of 30-40% with respect to single-planet solutions; mass
and orbital inclination can be measured to better than 10% for periods as short
as 0.1 yr, and for as low as , while
is required in order to measure with similar
accuracy systems harboring objects with periods as long as three times the
mission duration. For systems with all components producing
or greater, quasi-coplanarity can be reliably
established with uncertainties of a few degrees, for periods in the range
yr; in systems where at least one component has
, coplanarity measurements are compromised, with typical
uncertainties on the mutual inclinations of order of . Our
findings are illustrative of the importance of the contribution SIM will make
to the fields of formation and evolution of planetary systems.Comment: 61 pages, 14 figures, 5 tables, to appear in the September 2003 Issue
of the Publications of the Astronomical Society of the Pacifi
Testing Planet Formation Models with Gaia as Astrometry
In this paper, we first summarize the results of a large-scale double-blind
tests campaign carried out for the realistic estimation of the Gaia potential
in detecting and measuring planetary systems. Then, we put the identified
capabilities in context by highlighting the unique contribution that the Gaia
exoplanet discoveries will be able to bring to the science of extrasolar
planets during the next decade.Comment: 4 pages, 1 figure. To appear in the proceedings of "IAU Symposium 248
- A Giant Step: from Milli- to Micro-arcsecond Astrometry", held in Shanghai,
China, 15-19 Oct. 200
Astrometry and Exoplanets: the Gaia Era, and Beyond
The wealth of information in the Gaia catalogue of exoplanets will constitute
a fundamental contribution to several hot topics of the astrophysics of
planetary systems. I briefly review the potential impact of Gaia micro-arsec
astrometry in several areas of exoplanet science, discuss what key follow-up
observations might be required as a complement to Gaia data, and shed some
light on the role of next generation astrometric facilities in the arena of
planetary systems.Comment: 6 pages, 1 figure. Proceedings of the final ELSA Conference 'Gaia: at
the frontiers of astrometry', Sevres (France), 7-11 June 2010. To appear in
EAS Publication Series, EDP Science
The Luminosity Function of QSO Host Galaxies
We present some results from our HST archival image study of 71 QSO host
galaxies. The objects are selected to have z < 0.46 and total absolute
magnitude M_V < -23 (H_0=50 km/s/Mpc). This initial study investigates host
morphology and radio loudness, and it derives the QSO host galaxy luminosity
function. We have analyzed available WFPC2 broad band images, using a uniform
set of procedures. The host galaxies span a narrow range of luminosities and
are exceptionally bright, much more so than normal galaxies, usually L > L*_V.
The QSOs are almost equally divided among radio-loud QSOs with elliptical
hosts, radio-quiet QSOs with elliptical hosts, and radio-quiet QSOs with spiral
hosts. Using a weighting procedure, we derive the combined luminosity function
of QSO host galaxies. We find that the luminosity function of QSO hosts differs
in shape from that of normal galaxies but that they coincide at the highest
luminosities. The ratio of the number of quasar hosts to the number of normal
galaxies at a luminosity L_V is R = [L_V/(11.48 L*_V)]^2.46, where L*_V
corresponds to M*_V = -22.35, and a QSO is defined to be an object with total
nuclear plus host light M_V < -23. This ratio can be interpreted as the
probability that a galaxy with luminosity L_V will host a QSO at redshift z ~
0.26. (Abridged)Comment: 36 pages, 11 figures, LaTeX. Expanded analysis and additional
figures. To be published in the Astrophysical Journal, v576, September 1,
200
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