* Astronomy

Members Login
Username 
 
Password 
    Remember Me  
Home -> Astronomy News -> Astronomy News -> HARPS spectrograph
Post Info TOPIC: HARPS spectrograph
Blobrana


L

Posts: 131433
Date:
RE: HARPS spectrograph
Permalink  
 

Title: The HARPS search for southern extra-solar planets XXXIV. Occurrence, mass distribution and orbital properties of super-Earths and Neptune-mass planets
Authors: M. Mayor, M. Marmier, C. Lovis, S. Udry, D. Ségransan, F. Pepe, W. Benz, J.-L. Bertaux, F. Bouchy, X. Dumusque, G. Lo Curto, C. Mordasini, D. Queloz, N. C. Santos

We report on the results of an 8-year survey carried out at the La Silla Observatory with the HARPS spectrograph to detect and characterize planets in the super-Earth and Neptune mass regime. The size of our star sample and the precision achieved with HARPS have allowed the detection of a sufficiently large number of low-mass planets to study the statistical properties of their orbital elements, the correlation of the host-star metallicity with the planet masses, as well as the occurrence rate of planetary systems around solar-type stars. A robust estimate of the frequency of systems shows that more than 50% of solar-type stars harbour at least one planet of any mass and with period up to 100 days. Different properties are observed for the population of planets less massive than about 30M-Earth compared to the population of gaseous giant planets. The mass distribution of Super-Earths and Neptune-mass planets (SEN) is strongly increasing between 30 and 15M-Earth. The SEN occurence rate does not exhibit a preference for metal rich stars. Most of the SEN planets belong to multi-planetary systems. The orbital eccentricities of the SEN planets seems limited to 0.45. At the opposite, the occurence rate of gaseous giant planets is growing with the logarithm of the period, and is strongly increasing with the host-star metallicity. About 14% of solar-type stars have a planetary companion more massive than 50M-Earth? on an orbit with a period shorter than 10 years. Orbital eccentricities of giant planets are observed up to 0.9 and beyond. The precision of HARPS-type spectrographs opens the possibility to detect planets in the habitable zone of solar-type stars. Identification of a significant number of super-Earths orbiting solar-type of the Sun vicinity is achieved by Doppler spectroscopy. 37 newly discovered planets are announced in the Appendix of this paper, among which 15 Super-Earths.

Read more  (2251kb, PDF)



__________________
Blobrana


L

Posts: 131433
Date:
HARPS exoplanet findings
Permalink  
 

Fifty new exoplanets discovered

Astronomers using a telescope in Chile have discovered 50 previously unknown exoplanets.
The bumper haul of new worlds includes 16 "super-Earths" - planets with a great mass than our own, but below those of gas giants such as Jupiter.
One of these super-Earths orbits inside the habitable zone - the region around a star where conditions could be hospitable to life.
The planets were discovered using the Harps telescope at La Silla in Chile.
Read more



__________________
Blobrana


L

Posts: 131433
Date:
HARPS
Permalink  
 

Fifty New Exoplanets Discovered by HARPS

Astronomers using ESO's world-leading exoplanet hunter HARPS have today announced a rich haul of more than 50 new exoplanets, including 16 super-Earths, one of which orbits at the edge of the habitable zone of its star. By studying the properties of all the HARPS planets found so far, the team has found that about 40% of stars similar to the Sun have at least one planet lighter than Saturn.
The HARPS spectrograph on the 3.6-metre telescope at ESO's La Silla Observatory in Chile is the world's most successful planet finder. The HARPS team, led by Michel Mayor (University of Geneva, Switzerland), today announced the discovery of more than 50 new exoplanets orbiting nearby stars, including sixteen super-Earths. This is the largest number of such planets ever announced at one time. The new findings are being presented at a conference on Extreme Solar Systems where 350 exoplanet experts are meeting in Wyoming, USA.
Read more 



__________________
Blobrana


L

Posts: 131433
Date:
HARPS exoplanet findings
Permalink  
 

ESO to hold virtual press conference to discuss major HARPS exoplanet findings

On Monday 12 September 2011, astronomers will report significant new results in the field of exoplanets, obtained with the High Accuracy Radial Velocity Planet Searcher, better known as HARPS, the spectrograph on ESO's 3.6-metre telescope at La Silla Observatory  in Chile.
An online press conference to announce the new results and offer journalists the opportunity for discussion with the scientists will be held at 16:00 CEST on Monday, 12 September 2011.
Read more 

See GJ 1214b and CoRoT-7b



__________________
Blobrana


L

Posts: 131433
Date:
Permalink  
 

Title: Combining Kepler and HARPS Occurrence Rates to Infer the Period-Mass-Radius Distribution of Super-Earths/Sub-Neptunes
Authors: A. Wolfgang, G. Laughlin

The ongoing High Accuracy Radial velocity Planet Search (HARPS) has found that 30-50% of GK dwarfs in the solar neighbourhood host planets with sub-Neptune masses in orbits of P < 50 days. At first glance, this overall occurrence rate seems inconsistent with the planet frequency measured during Q0-Q2 of the Kepler Mission, whose 1,235 detected planetary candidates imply that ~ 15% of main sequence dwarfs harbour short-period planets with R_pl < 4 R_Earth. A rigorous comparison between the two surveys is difficult, however, as they observe different stellar populations and measure different planetary properties. Here we report the results of a Monte Carlo study that can account for this discrepancy via plausible distributions of planetary compositions. We find that a population concurrently consisting of (1) dense silicate-iron planets and (2) low-density gas-dominated worlds provides a natural fit to the current data. In this scenario, the fraction of dense planets decreases with increasing mass, from f_rocky = 90% at M = 1 M_Earth to f_rocky = 10% at M = 17 M_Earth. Our best fit population has a total occurrence rate of 40% for 2 < P < 50 days and 1 < M < 17 M_Earth, and is characterised by simple power-law indices of the form N(M)dM ~ M^alpha dM and N(P)dP ~ P^beta dP with alpha = -1.0 and beta = 0.0. Our model population therefore contains four free parameters and is readily testable with future observations. Furthermore, our model's insistence that at least two distinct types of planets must exist in the survey data indicates that multiple formation mechanisms are at work to produce the population of planets commonly referred to as "super-Earths".

Read more  (684kb, PDF)



__________________
Blobrana


L

Posts: 131433
Date:
RE: HARPS spectrograph
Permalink  
 

HARPS: The Planet Hunter
HARPS is the ESO facility for the measurement of radial velocities with the highest accuracy currently available. It is fibre-fed by the Cassegrain focus of the 3.6m telescope in La Silla.
The instrument is built to obtain very high long term radial velocity accuracy (on the order of 1 m/s). To achieve this goal, HARPS is designed as an echelle spectrograph fed by a pair of fibres and optimised for mechanical stability. It is contained in a vacuum vessel to avoid spectral drift due to temperature and air pressure variations. One of the two fibres collects the star light, while the second is used to either record simultaneously a Th-Ar reference spectrum or the background sky. The two HARPS fibres (object + sky or Th-Ar) have an aperture on the sky of 1"; this produces a resolving power of 115,000 in the spectrograph. Both fibres are equipped with an image scrambler to provide a uniform spectrograph pupil illumination, independent of pointing decentering. The spectral range covered is 378nm-691nm, distributed over the echelle orders 89-161. As the detector consists of a mosaic of 2 CCDs (altogether 4k x 4k, 15 microns pixels), one spectral order (N=115, from 530nm to 533nm) is lost in the gap between the two chips.

Read more

__________________
Blobrana


L

Posts: 131433
Date:
HARPS-NEF spectrograph
Permalink  
 

Astronomers have announced plans to build an ultra-stable, high-precision spectrograph for the Science and Technology Facilities Council's 4.2-m William Herschel Telescope (WHT - part of the Isaac Newton Group or ING on La Palma) in an effort to discover habitable Earth-like planets around other stars.

Read more

__________________
Blobrana


L

Posts: 131433
Date:
HARPS spectrograph
Permalink  
 

The HARPS-N spectrograph is a high-precision instrument, similar to HARPS on the 3.6-m ESO telescope in Chile. It will be located in the Northern hemisphere on the William-Herschel Telescope to allow for synergy with the NASA Kepler mission. The main scientific rationale of HARPS-N is the characterisation and discovery of terrestrial planets by combining transits and Doppler measurements.

Read more

__________________
Page 1 of 1  sorted by
 
Quick Reply

Please log in to post quick replies.
Home -> Astronomy News -> Astronomy News -> HARPS spectrograph


Create your own FREE Forum
Report Abuse 		Powered by ActiveBoard