Objectives
The Gaia space mission has the following objectives:
- To determine the intrinsic luminosity of a star requires knowledge of its distance. One of the only ways to achieve without physical assumptions is through the star's parallax. Ground-based observations would not measure such parallaxes with sufficient precision due to the effects of the atmosphere and instrumental biases.
- Observations of the faintest objects will provide a more complete view of the stellar luminosity function. All objects up to a certain magnitude must be measured in order to have unbiased samples.
- A large number of objects are needed to examine the more rapid stages of stellar evolution. Observing a large number of objects in the galaxy is also important in order to understand the dynamics of our galaxy. Note that a billion stars represents less than 1% of the content of our Milky Way galaxy.
- Measuring the astrometric and kinematic properties of a star is necessary in order to understand the various stellar populations, especially the most distant.
Gaia is expected to:
- Measure the astrometric properties of over a billion stars down to an apparent magnitude (V) of V = 20
- Determine the positions of stars at a magnitude of V=10 down to a precision of 7 millionths of an arcsecond (μas) (this is equivalent to measuring the diameter of a hair from 1000 km away); between 12 and 25 μas down to V = 15, and between 100 and 300 μas to V = 20, depending on the color of the star
- Determine the distances to the nearest stars within 0.001%, and to stars near the galactic center, 30,000 light years away, within 20%
- Measure the tangential speed of 40 million stars to a precision of better than 0.5 km/s
- Measure the orbits and inclinations of a thousand extrasolar planets accurately, determining their true masses using astrometric planet detection methods
Among other results relevant to fundamental physics, Gaia will detect the bending of starlight by the Sun’s gravitational field, as predicted by Albert Einstein’s General Theory of Relativity, and therefore directly observe the structure of space-time.
Read more about this topic: Gaia (spacecraft)
Famous quotes containing the word objectives:
“Along the journey we commonly forget its goal. Almost every vocation is chosen and entered upon as a means to a purpose but is ultimately continued as a final purpose in itself. Forgetting our objectives is the most frequent stupidity in which we indulge ourselves.”
—Friedrich Nietzsche (1844–1900)