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10 June 2022The animation shows a Hertzsprung-Russell Diagram built with Gaia EDR3 G, G_RP, G_BP magnitudes and parallaxes for a sample of 14,351,682 low extinction stars in the Milky Way, together with two different representations of the composite BP/RP spectra of a selection of stars along the Main Sequence, the Red Giant Branch and the White Dwarf...
9 June 2022Gaia Data Release 3 (Gaia DR3) will offer for the first time access to a large selection of mean low-resolution spectra obtained from the Blue and Red Photometer instruments (BP/RP). Spectra for about 220 million sources, mostly brighter than 17.65 in G, will be available in the internal reference system and in the absolute system both in terms...
27 May 2022The variable stars that nowadays are collectively called Cepheids are actually an ensemble of different types identifying three main groups: Classical Cepheids, type II Cepheids and anomalous Cepheids. Classical Cepheids are fundamental standard candles of the extragalactic distance scale. They are also important tracers of the young (~50-500...
23 May 2022The full 3rd Data Release of Gaia will provide to the community an impressive amount of ~220 million XP spectra, both internally and externally calibrated (De Angeli et al 2022, Montegriffo et al 2022). Spectra for all types of sources will be represented, as long as visible at the limiting magnitude: the database of spectra will be...
19 May 2022The Gaia Data Release 3 (DR3) will offer access for the first time to mean low-resolution spectra obtained from a combination of a number of epoch Blue and Red Photometer (BP and RP) observations covering the optical to near-infrared wavelength range [330, 1050] nm. These will be available for about 220 million sources, mostly brighter than...
25 February 2022RR Lyrae are low mass (typical masses around 0.6-0.8 solar masses), old stars (ages larger than 9-10 billion years) whose surface expands and contracts regularly with periods shorter than one day. The pulsation gives rise to a variation of brightness occurring in two main flavours. First of all, the c-type RR Lyrae (RRc) have sinusoidal light...
31 January 2022Many exoplanets are known to orbit stars in the solar neighbourhood but for only a few it was so far possible to measure the tiny corresponding motion of the host star in the plane of the sky. And when it has been achieved, e.g. with the Hubble Space Telescope (McArthur et al. 2010), the Very Large Telescope (Sahlmann et al. 2016), or Very Long...
23 December 2021The upcoming 3rd Gaia Data Release (Gaia DR3) will introduce for the first time BP/RP mean spectra in the wide range of Gaia data products. The exact number of sources for which BP/RP mean spectra will be published is still undefined but it is expected to be of the order of 100 million. The vast majority of these sources will be brighter than...
9 July 2021Gaia RVS stellar spectra, at a resolution of ~11500, contain a wealth of information about Milky Way stars. This animation shows several Gaia RVS stellar spectra, presenting the stellar flux (black dots) in the wavelength interval between 846 and 870 nm (in vacuum). The flux is normalized to the continuum, showing variations (spectral lines) due...
27 April 2021In 2015, after one year of data acquisition by Gaia, we reported the case of HIP 70674, a well-known double lined spectroscopic binary (SB2), with visual magnitude V=7.99. The aim was to demonstrate the capability of the Coordination Unit 6 (CU6) Single Transit Analysis (STA) pipeline to measure radial velocities from double lined spectra as...
30 March 2021Gaia is sampling more than a billion Milky-Way stars at a mean rate of 15 times per year. The Gaia scanning law was optimised for obtaining precise astrometry and is therefore not optimal for detecting planets that transit periodically the disk of their host stars. Nevertheless, this type of events can in principle be seen in the Gaia data. In...
22 December 2020The Gaia mission’s primary objective is to measure the parallaxes and proper motions of stars in the Milky Way. Yet, Gaia also relies on very distant objects to define its reference frame. In fact, Gaia also sees several millions of distant galaxies and in particular quasi-stellar objects, or quasars (QSOs). Along its journey through the cosmos,...
12 August 2020Gaia has proven to be a powerful tool providing very precise astrometry and photometry in the first releases of the mission (see Gaia DR2 and Gaia DR1). The third release and beyond (find here the current release scenario planning) will include some calibrated spectrophotometric data.
Spectrophotometry in Gaia is obtained using two prisms. Each...
