5. HIPPARCOS MISSION - HIgh Precision PARallax
COllecting Satellite
5.1 Why the HIPPARCOS Mission ?
Astronomers have gathered measurements of stars for a long time. They've
given them a determined name, a position on the celestial sphere and they have studied the
properties of stars (brightness, temperature, mass, stellar abundances...).
But the observations are limited by gravitation, the atmospheric turbulence
and the motion of the Earth. So the scientists have developed space projects to obtain better accuracy:
the HUBBLE Space Telescope and the HIPPARCOS satellite mission are such examples.
The HIPPARCOS project is an astrometric space mission developed by ESA (The European Space Agency).
The purpose of the mission was:
» to observe nearly 120000 selected stars
» to collect astrometric and photometric data for all of them
» to compile a catalog with these data.
The mission started in august 1989 and ended succesfully in 1993.
5.2 HIPPARCOS and Double Stars
The INput CAtalog (INCA) of the HIPPARCOS mission, necessary to
program the HIPPARCOS satellite, contains 11434 double stars. During the
mission, the satellite took up to 100 measurements of the known double stars and discovered
some 3000 new ones!
The scientists have important
information to improve their knowledge about double stars (parallaxes, proper motions and magnitudes...).
5.3 Data from the HIPPARCOS Mission
HIP 71681(B)/71683(A) alpha Centauri A and B
| Parallax [arcsec] |
Distance [pc] |
Hp Magnitude A |
Hp Magnitude B |
| 0.7421±0.0014 |
1.35±0.00254 |
0.1373 |
1.2429 |
before HIPPARCOS
HIP 87895(AB)
| Parallax [arsec] |
Distance [pc] |
Hp Magnitude |
| 0.0350±0.0007 |
28.56±0.53 |
6.4543 |
before HIPPARCOS
HIP 24608(AB) Capella
| Parallax [arsec] |
Distance [pc] |
Hp Magnitude |
| 0.0773±0.0009 |
12.94±0.15 |
0.2385 |
before HIPPARCOS
HIP 31173(AB) WW Aurigae A and B
| Parallax [arsec] |
Distance [pc] |
Period [days] |
Maximum Magnitude |
Minimum Magnitude |
| 0.0119±0.0011 |
84.32±7.54 |
2.52502 |
5.820 |
6.300 |
before HIPPARCOS
If you want more information go to: HIPPARCOS Astronomy Mission
The HIPPARCOS catalogue contributes significantly to improve our knowledge of stellar
and galactic sciences. Even after several centuries of observations and studies, the Universe
still has some mysteries. We will need other projects
as GAIA
(a possible future interferometric space mission) and also a lot of patience to gain even
better understanding of the Universe and its double stars.
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