Exoplanets & Stellar Populations Group

HARPS-N project

HARPS-N is a high-resolution (R=120,000) optical spectrograph with broad wavelength coverage (378-691 nm) optimized for high-precision (sub-meter) radial-velocity measurement dedicated to exoplanet search and mounted at the Italian Telescopio Nazionale Galileo (TNG).
Our group in involved in two main projects based on HARPS-N:

• GTO project
  The HARPS-N Consortium is a collaboration among various institutes of different countries for the construction and operation of HARPS-N. Within the agreement between HARPS-N Consortium and INAF, 400 nights (80 nights/year for 5 years) of guarantee time observations were allocated. The main scientific goal of the HARPS-N Consortium GTO is the discovery and characterization of terrestrial exoplanets by achieving long-term sub-meter per second radial-velocity precision on V < 12 mag stars.
  NASA’s Kepler mission was launched in March 2009. Kepler monitors a single field in Cygnus/Lyra (RA=19:23, Dec=+44.5) for at least 3.5 years and has already identified nearly a thousand transiting planet candidates orbiting preselected main sequence stars (F to M type) of V= 11-15 mag.  Kepler is capable of detecting dozens of Earth-sized planets in orbits with periods up to about one year, as well as several hundred super-Earths.  To confirm and characterize the rocky planets identified by Kepler, it is critical to determine orbital solutions so that the planetary masses can be established.  With its ability to measure velocities with a precision better than 1 m/s, HARPS-N will provide a unique capability for determining the masses of Kepler planets similar to the Earth.
  The primary project of the HARPS-N Consortium GTO has three broad scientific goals that can be achieved by delivering planetary masses of certain precision:
  
  1.  confirming an Earth-twin planet in the habitable zone of a G5V star or later, with a precision of 30% in mass;
  2.  characterizing Earth-like planets of 2-5 Earth masses ("super-Earths") in various orbits with enough precision to distinguish between water-rich and dry planets;
  3.  characterizing the transition between super-Earths and Ice Giants (hot Neptunes, for example) near 10 Earth masses, with a precision of 5% in mass, or better.
  As a secondary goal, HARPS-N Consortium plans to observe a sample of the brightest, least active, and least noisy northern stars. The goal is to discover Earth-like planets and multiple planet systems. The value of such discoveries is that a number of exciting follow-up possibilities become possible for such nearby objects. While bright stars do not require very long exposure times, in order to achieve long-term precision below ~50 cm/s we have to devote additional observing time to characterize the stellar p-mode oscillations, granulation noise power, and rotation induced variations. This project will require 10 - 20 clear nights per year, in order to be scientifically viable.
  The primary targets for this project can be identified before any observing with HARPS-N begins.
  For further information: HARPS-N homepage or contact Giampaolo Piotto.
  Related papers to GTO project:
  • Motalebi et al. (2015), A&A, 584, 72
  • Bonomo et al. (2014), A&A, 572, 2
  • Dumusque et al. (2014) ApJ, 789, 154


• GAPS project
  Given the opportunity of HARPS-N at TNG, a number of Italian scientists active in the field of exo-planetology have joined into a common project called “Global Architecture of Planetary Systems” (GAPS). The aim is to optimize the HARPS-N open time by sharing not only the time between different project but also the knowledge and the expertise of each GAPS team member in high-resolution spectroscopy, stellar activity, crowded stellar environments, planetary systems formation, planetary dynamics, and data handling.
  As the name says, the main goal of this project is to expand our understanding on formation and evolution of planetary systems. This is accomplished by tackling the problem from several perspective:
  1. by studying the frequency of low-mass planets as a function of stellar mass, stellar metallicity, density of the stellar environment;
  2. by characterizing known planetary systems;
  3. by analyzing the activity of the host stars and its effect on the derivation of the planet parameters;
  4. by deriving accurate measurements of planet mass by means of asteroseismologic study of the host stars.
  Since August 2012 360h/semester of HARPS-N time have been devoted to this project.
  Our group is currently leading a survey to detect new planets around Main Sequence stars in two old nearby open clusters. We are also taking care of characterizing known or candidate planets detected by other survey in crowded stellar environments, such as open or globular clusters. The ultimate goal is to statistically determine the occurrence of planets in such systems.
  Our effort lead to the discovery of the first multi-planet system in an open cluster (Malavolta et al. 2016).
  For further information: GAPS project homepage or contact Giampaolo Piotto.
  Related papers to GTO project:
  • Malavolta et al. (2016) A&A, 588, 118
    The code used in the paper is available here: PyORBIT by Luca Malavolta on .