Spectroscopic survey of the Galaxy with Gaia– I. Design and performance of the Radial Velocity Spectrometer

The definition and optimization studies for the Gaia satellite spectrograph, the 'radial velocity spectrometer' (RVS), converged in late 2002 with the adoption of the instrument baseline. This paper reviews the characteristics of the selected configuration and presents its expected performance. The RVS is a 2.0 x 1.6 degree integral field spectrograph, dispersing the light of all sources entering its field of view with a resolving power R = lambda/Deltalambda = 11 500 over the wavelength range [848, 874] nm. The RVS will continuously and repeatedly scan the sky during the 5-yr Gaia mission. On average, each source will be observed 102 times over this period. The RVS will collect the spectra of about 100-150 million stars up to magnitude V similar or equal to 17-18. At the end of the mission, the RVS will provide radial velocities with precisions of similar to2 km s(-1) at V = 15 and similar to15-20 km s(-1) at V = 17, for a solar-metallicity G5 dwarf. The RVS will also provide rotational velocities, with precisions (at the end of the mission) for late-type stars of sigma(upsilonsin) similar or equal to (i) similar or equal to 5 km s(-1) at V similar or equal to 15 as well as atmospheric parameters up to V similar or equal to 14-15. The individual abundances of elements such as silicon and magnesium, vital for the understanding of Galactic evolution, will be obtained up to V similar or equal to 12-13. Finally, the presence of the 862.0-nm diffuse interstellar band (DIB) in the RVS wavelength range will make it possible to derive the three-dimensional structure of the interstellar reddening.

[1]  Lincoln Hallen,et al.  The impact of very high speed integrated circuit technology on SpaceStation logistics , 1988 .

[2]  M. Spite,et al.  The impact of very high S/N spectroscopy on stellar physics : proceedings of the 132nd Symposium of the International Astronomical Union, held in Paris, France, June 29-July 3, 1987 , 1988 .

[3]  L. Prévot,et al.  Complementary astrophysical data for Hipparcos stars. (1) Astrophysical fundamental parameters of early-type Hipparcos stars. (2) Radial velocities of southern late-type Hipparcos stars. Profile of two key programmes. , 1989 .

[4]  R. Kurucz.  ATLAS9 Stellar Atmosphere Programs and 2 km/s grid. , 1993 .

[5]  Robert L. Kurucz,et al.  SYNTHE Spectrum Synthesis Programs and Line Data. , 1993 .

[6]  M. G. Cerutti-Maori,et al.  Space Optics 1994: Earth Observation and Astronomy , 1994 .

[7]  George H. Herbig,et al.  The Diffuse Interstellar Bands , 1995 .

[8]  P. Kenneth Seidelmann,et al.  Astronomical and astrophysical objectives of sub-milliarcsecond optical astrometry : proceedings of the 166th Symposium of the International Astronomical Union, held in the Hague, the Netherlands, August 15-19, 1994 , 1995 .

[9]  C. Boisson,et al.  Spectra of late type stars from 4800 to 9000 Å , 1996 .

[10]  J. Carquillat,et al.  An Atlas of the infrared spectral region - II. The late-type stars (G - M) , 1997 .

[11]  B. Chen,et al.  Comparisons of a Galactic Kinematic Model with Two Proper-Motion Surveys in the Vicinity of the North Galactic Pole , 1997 .

[12]  Library of high-resolution UES echelle spectra of F, G, K and M field dwarf stars , 1997, astro-ph/9709004.

[13]  L. Mestel.  Stellar magnetism , 1999 .

[14]  L. Ramsey,et al.  Library of Medium-Resolution Fiber Optic Echelle Spectra of F, G, K, and M Field Dwarfs to Giant Stars , 1999, astro-ph/9901411.

[15]  H. C. Stempels,et al.  VALD{2: Progress of the Vienna Atomic Line Data Base ? , 1999 .

[16]  M. G. Lattanzi,et al.  GAIA: Composition, formation and evolution of the Galaxy , 2001, astro-ph/0101235.

[17]  Spain.,et al.  Empirical calibration of the near-infrared Ca ii triplet — I. The stellar library and index definition , 2001, astro-ph/0109157.

[18]  P. Sonnentrucker,et al.  Unusually Weak Diffuse Interstellar Bands toward HD 62542 , 2002 .

[19]  Tomaz Zwitter,et al.  GAIA accuracy on radial velocities assessed from a synthetic spectra database , 2002 .

[20]  F. Mignard.  Observations of solar system objects with GAIA I. Detection of NEOS , 2002 .

[21]  U. Munari,et al.  High resolution spectroscopy over $\mathsf{\lambda\lambda}$ 8500-8750 Å for GAIA - IV. Extending the cool MK stars sample , 2003 .

[22]  An automated system to classify stellar spectra – I , 2002, astro-ph/0212138.

[23]  Ulisse Munari,et al.  GAIA Spectroscopy: Science and Technology , 2003 .

[24]  John L. Tonry,et al.  Photometric Observations Using Orthogonal Transfer CCDs , 2003 .

[25]  Harinder P. Singh,et al.  The Indo-US Library of Coudé Feed Stellar Spectra , 2004, astro-ph/0402435.

[26]  Dept. of Physics,et al.  An extensive library of synthetic spectra covering the far red, RAVE and GAIA wavelength ranges , 2004, astro-ph/0401069.

[27]  A. Bijaoui,et al.  Spectroscopic Survey of the Galaxy with Gaia II. The expected science yield from the Radial Velocity Spectrometer , 2005, astro-ph/0506083.