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Astrometry is a branch of astronomy that involves precise measurements of the positions and movements of stars and other celestial bodies. It provides the kinematics and physical origin of the Solar System and our galaxy, the Milky Way.
Hipparcos was a scientific satellite of the European Space Agency (ESA), launched in 1989 and operated until 1993. It was the first space experiment devoted to precision astrometry, the accurate measurement of the positions of celestial objects on the sky. This permitted the first high-precision measurements of the intrinsic brightnesses, proper motions, and parallaxes of stars, enabling better calculations of their distance and tangential velocity. When combined with radial velocity measurements from spectroscopy, astrophysicists were able to finally measure all six quantities needed to determine the motion of stars. The resulting Hipparcos Catalogue, a high-precision catalogue of more than 118,200 stars, was published in 1997. The lower-precision Tycho Catalogue of more than a million stars was published at the same time, while the enhanced Tycho-2 Catalogue of 2.5 million stars was published in 2000. Hipparcos' follow-up mission, Gaia, was launched in 2013.
Gaia is a space observatory of the European Space Agency (ESA), launched in 2013 and expected to operate until c. 2022. The spacecraft is designed for astrometry: measuring the positions, distances and motions of stars with unprecedented precision. The mission aims to construct by far the largest and most precise 3D space catalog ever made, totalling approximately 1 billion astronomical objects, mainly stars, but also planets, comets, asteroids and quasars, among others.
Gamma Ursae Majoris, formally named Phecda, is a star in the constellation of Ursa Major. Since 1943, the spectrum of this star has served as one of the stable anchor points by which other stars are classified. Based upon parallax measurements with the Hipparcos astrometry satellite, it is located at distance of around 83.2 light-years from the Sun.
Epsilon Boötis, officially named Izar, is a binary star in the northern constellation of Boötes. The star system can be viewed with the unaided eye at night, but resolving the pair with a small telescope is challenging; an aperture of 76 mm (3.0 in) or greater is required.
Beta Draconis, a name Latinized from β Draconis, is a binary star system and the third-brightest star in the northern circumpolar constellation of Draco. The two components are designated Beta Draconis A and B respectively. With a combined apparent visual magnitude of 2.79, it is bright enough to be easily seen with the naked eye. Based upon parallax measurements from the Hipparcos astrometry satellite, it lies at a distance of about 380 light-years from the Sun. The system is drifting closer with a radial velocity of −21 km/s.
Sigma Aquarii, Latinized from σ Aquarii, is a double star in the equatorial constellation of Aquarius, positioned about 1.3° to the south of the ecliptic. Due to its proximity to the ecliptic, this star is subject to occultation by the Moon. It has a white hue and is visible to the naked eye with an apparent visual magnitude of 4.81. Based upon parallax measurements, the distance to this star is approximately 175 light-years. It is drifting further away with a radial velocity of +11 km/s.
26 Aurigae is a binary star system in the northern constellation of Auriga. It is visible to the naked eye as a faint star with an apparent visual magnitude of 5.41.
40 Boötis is a single star located 166.5 light years away from the Sun in the northern constellation of Boötes. It is visible to the naked eye as a dim, yellow-white hued star with an apparent visual magnitude of 5.64. The star is moving away from the Earth with a heliocentric radial velocity of +12 km/s.
HD 36678 is single star in the northern constellation of Auriga. This star is dimly visible to the naked eye with an apparent visual magnitude of 5.83. It is located at a distance of approximately 840 light years from the Sun based on parallax. This is an aging red giant star with a stellar classification of M0III. It is currently on the asymptotic giant branch of the HR diagram, and has expanded to ~63 times the radius of the Sun. The star is radiating ~875 times the Sun's luminosity from its enlarged photosphere at an effective temperature of 3,950 K.
Zeta Chamaeleontis, Latinized from ζ Chamaeleontis, is a star located in the constellation Chamaeleon. Located around 570 light-years distant, it shines with a luminosity approximately 522 times that of the Sun and has a surface temperature of 13,544 K. South African Astronomer A.W.J. Cousins noted it to vary between magnitudes 5.06 and 5.17 in 1960. It was classified as a Beta Cephei variable in the Hipparcos and Tycho Catalogues, with a period of 1.07 days, before being reclassified as a Slowly pulsating B star in the 2011 version.
Lennart Lindegren is a member of the staff at Lund Observatory, Sweden, where he obtained his PhD in 1980, and became a full professor of astronomy in 2000. Space astrometry and its various applications has been his main focus in astronomy since 1976. His career has been marked by his continuous involvement in, leadership of, and profound contributions to, ESA's Hipparcos and Gaia missions over their entire duration.
Q Scorpii is an orange giant star in the constellation Scorpius. Its apparent magnitude is 4.27. It lies in the tail of Scorpius, between the stars λ Scorpii and μ Scorpii, 7′ from the faint globular cluster Tonantzintla 2.
74 Cygni is a visual binary star system in the northern constellation Cygnus, located around 249 light years distant from the Sun. It is visible to the naked eye as a faint, white-hued star with a combined apparent visual magnitude of 5.04. The pair orbit each other with a period of 1.57 years and an eccentricity of 0.5. The system is a source of X-ray emission, which is most likely coming from the secondary component.
V915 Scorpii is an orange hypergiant variable star in the constellation Scorpius.
64 Piscium is the Flamsteed designation for a close binary star system in the zodiac constellation of Pisces. It can be viewed with the naked eye, with the components having a combined apparent visual magnitude of 5.07. An annual parallax shift of 42.64 mas provides a distance estimate of 46.5 light years. The system is moving further from the Sun with a radial velocity of +3.76 km/s.
Gamma2 Fornacis, a name Latinized from γ2 Fornacis, is a single star in the southern constellation Fornax. It has a white hue and is faintly visible to the naked eye at night with an apparent visual magnitude of 5.4. The distance to Gamma2 Fornacis is approximately 520 light years based on parallax. It is drifting further away with a radial velocity of 24 km/s. Gamma1 Fornacis is a 6th magnitude star about four degrees to the north.
HD 73468(HR 3417) is a solitary star in the southern constellation Volans. With an apparent magnitude of 6.1, it can be only viewed under dark skies. The star is located 417 light-years (128 pc) based on parallax, but is drifting closer with a radial velocity of -25 km/s.
HD 60150 is a solitary star located in the constellation Volans. With an apparent magnitude of 6.39, it is close to the limiting magnitude for naked-eye visibility. The star is located 754 light years away from the Solar System, but is drifting away with a radial velocity of 14.14 km/s.
HD 28700 is a solitary star in the southern constellation Caelum. With an apparent magnitude of 6.12, it's only visible to the naked eye under ideal conditions. The star is located 385 light-years (118 pc) based on parallax, but is drifting away with a radial velocity of 11.5 km/s.
References
- ↑ "Michael Perryman Mapping the stars with maths". ESA. Retrieved 24 April 2018.
- ↑ Lindegren, L; Perryman, M. A.C (1996). "GAIA: Global astrometric interferometer for astrophysics". Astronomy and Astrophysics Supplement Series. 116 (3): 579. Bibcode:1996A&AS..116..579L. doi: 10.1051/aas:1996136 .
- ↑ Perryman, M. A. C; De Boer, K. S; Gilmore, G; Høg, E; Lattanzi, M. G; Lindegren, L; Luri, X; Mignard, F; Pace, O; De Zeeuw, P. T (2001). "GAIA: Composition, formation and evolution of the Galaxy". Astronomy & Astrophysics. 369: 339–363. arXiv: astro-ph/0101235 . Bibcode:2001A&A...369..339P. doi:10.1051/0004-6361:20010085. S2CID 28973535.
- ↑ "'HIPPARCOS AND THE HR DIAGRAM". Royal Astronomical Society. February 1997. Retrieved 25 April 2018.
- ↑ "Michael Perryman" . Retrieved 2018-04-24.
- ↑ "JPL Small-Body Database Browser". NASA.
- ↑ "Laureates Academy Medal". Royal Netherlands Academy of Arts and Sciences. Archived from the original on 24 March 2019.
- ↑ "Tycho Brahe Prize to Prof. Michael Perryman" (PDF). European Astronomical Society Press Release. Retrieved 31 May 2012.
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