Encyclopedia of Astronomy and Astrophysics, Books, Books eng, books NON FICTION, Astronomy
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Opik (Opik), Ernst Julius (1893–1985)
E
NCYCLOPEDIA OF
A
STRONOMY AND
A
STROPHYSICS
Opik (Opik), Ernst Julius (1893–1985)
Born in Estonia, Opik studied at Moscow University,
and helped establish Turkestan University in Tashkent,
becoming the Astronomer (director) at Tartu Observatory
in Estonia. He fled the Red Army by horse cart during
the Second World War and went to Armagh Observatory
(Northern Ireland) in 1948. His wide-ranging interests are
reflected in his discoveries and theories. These include
the discovery of degenerate stars, e.g. white dwarfs, in
his calculation of the density of o
2
Eridani (1915). He
calculated the distance of M31 as 450 000 parsecs from the
Sun (1922). He computed by hand evolutionary models
of main-sequence stars into giants (1938) over a decade
earlier than the computer computations of
HOYLE
and
SCHWARZSCHILD
. He predicted the density of craters on the
surface of Mars, which was confirmed 15 years later by
planetary probes. He put forward an unproven theory
of the Ice Ages based on a calculation of changes in the
convection in the internal structure of the Sun rather than
MILANKOVITCH
cycles.
Copyright © Nature Publishing Group 2001
Brunel Road, Houndmills, Basingstoke, Hampshire, RG21 6XS, UK Registered No. 785998
and Institute of Physics Publishing 2001
Dirac House, Temple Back, Bristol, BS1 6BE, UK
1
Ångstr om, Anders Jonas (1814–74)
E
NCYCLOPEDIA OF
A
STRONOMY AND
A
STROPHYSICS
Ångstr om, Anders Jonas (1814–74)
Physicist, born in Lodg o, Sweden. He was keeper of the
observatory and professor at Uppsala where he studied
heat, magnetism and optics and examined the spectra of
the Sun and auroras. His name is commemorated with
the
angstrom unit
,10
−
10
m, which is used for measuring
wavelengths of light and x-rays, and the separation of
atoms in molecules and crystals.
Copyright © Nature Publishing Group 2001
Brunel Road, Houndmills, Basingstoke, Hampshire, RG21 6XS, UK Registered No. 785998
and Institute of Physics Publishing 2001
Dirac House, Temple Back, Bristol, BS1 6BE, UK
1
61 Cygni
E
NCYCLOPEDIA OF
A
STRONOMY AND
A
STROPHYSICS
61 Cygni
The star 61 Cygni is important because of its large proper
motion, first measured at the Palermo Observatory by
Giuseppe Piazzi (1746–1826). The star became popularly
known as ‘Piazzi’s flying star’. Its measured annual proper
motion of 5.23
is still the seventh largest known, and is
the largest for a naked-eye star (apparent magnitude 4.8).
This star was also the first to have its annual parallax
reliably determined, by Friedrich Bessel (1784–1846).
Bessel’s measurement of 0.314
, made at K onigsberg with
Fraunhofer’s 6.25 inch heliometer in 1838, compares quite
well with the modern value of 0.286
. Determinations of
stellar parallax made in the same year by other observers
were far less accurate. It is the eleventh closest star, at a
distance of 11.4 light-years.
61 Cygni is also a well-known binary system, with
a period of 653.3 years. Its components are currently
separated by 30.3
at position angle 150
◦
. The primary
star 61 Cyg A is an orange dwarf, spectral type K5V,
of apparent magnitude 5.20 and absolute magnitude 7.5.
Its companion 61 Cyg B is also an orange dwarf, of
spectral type K7V, with an apparent magnitude of 6.05
and absolute magnitude 8.3. The system is reputed
to be the most extensively observed double star, some
thousands of visual observations being supplemented by
more than 34 000 photographic plates. Precise astrometric
measurements of these plates have indicated that the
system has at least one invisible component, believed to
be a planet of similar mass to Jupiter, and perhaps as many
as three, with orbital periods of between 5 and 12 years.
Copyright © Nature Publishing Group 2001
Brunel Road, Houndmills, Basingstoke, Hampshire, RG21 6XS, UK Registered No. 785998
and Institute of Physics Publishing 2001
Dirac House, Temple Back, Bristol, BS1 6BE, UK
1
Abastumani Astrophysical Observatory
E
NCYCLOPEDIA OF
A
STRONOMY AND
A
STROPHYSICS
Abastumani Astrophysical
Observatory
The Abastumani Astrophysical Observatory (AbAO)—
longitude, 42.83; latitude, 41.81 degrees—was founded in
1932. It is located in Abastumani, in the south-west part
of the Republic of Georgia, 250 km west of the capital city
Tbilisi, on the top of Mount Kanobili at 1700 m.
AbAO’s primary mission is to enable astronomers
of the former Soviet Union to carry out high-quality
observations. The average number of clear nights is
130 per year with 25% of seeings smaller than one
arcsec. At present, about 100 staff members work at the
Observatory in six departments and four laboratories. The
Observatory’s main facilities are 125 cm Ritchey–Chretien
and 70 cm meniscus telescopes.
The major research areas are accretion disks and
pulsars astrophysics, solar system cosmogony, objec-
tive prism spectroscopy, low-amplitude short-period vari-
ables, AGNs variability, solar physics, solar–terrestrial
phenomena and atmospheric physics.
For further information see
Copyright © Nature Publishing Group 2001
Brunel Road, Houndmills, Basingstoke, Hampshire, RG21 6XS, UK Registered No. 785998
and Institute of Physics Publishing 2001
Dirac House, Temple Back, Bristol, BS1 6BE, UK
1
Abbe, Ernst (1840–1905)
E
NCYCLOPEDIA OF
A
STRONOMY AND
A
STROPHYSICS
Abbe, Ernst (1840–1905)
Born in Eisenach, Grand Duchy of Saxe-Weimar-Eisenach
(now Germany), Abbe became director of the observatory
at Jena and research director of the
CARL ZEISS
optical works
in Jena. He discovered the
Abbe sine condition
, which
describes a lens that will form an image, without defects
of coma and spherical aberration. His mathematical
treatment founded the present-day science of optics.
Copyright © Nature Publishing Group 2001
Brunel Road, Houndmills, Basingstoke, Hampshire, RG21 6XS, UK Registered No. 785998
and Institute of Physics Publishing 2001
Dirac House, Temple Back, Bristol, BS1 6BE, UK
1
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Opik (Opik), Ernst Julius (1893–1985)
E
NCYCLOPEDIA OF
A
STRONOMY AND
A
STROPHYSICS
Opik (Opik), Ernst Julius (1893–1985)
Born in Estonia, Opik studied at Moscow University,
and helped establish Turkestan University in Tashkent,
becoming the Astronomer (director) at Tartu Observatory
in Estonia. He fled the Red Army by horse cart during
the Second World War and went to Armagh Observatory
(Northern Ireland) in 1948. His wide-ranging interests are
reflected in his discoveries and theories. These include
the discovery of degenerate stars, e.g. white dwarfs, in
his calculation of the density of o
2
Eridani (1915). He
calculated the distance of M31 as 450 000 parsecs from the
Sun (1922). He computed by hand evolutionary models
of main-sequence stars into giants (1938) over a decade
earlier than the computer computations of
HOYLE
and
SCHWARZSCHILD
. He predicted the density of craters on the
surface of Mars, which was confirmed 15 years later by
planetary probes. He put forward an unproven theory
of the Ice Ages based on a calculation of changes in the
convection in the internal structure of the Sun rather than
MILANKOVITCH
cycles.
Copyright © Nature Publishing Group 2001
Brunel Road, Houndmills, Basingstoke, Hampshire, RG21 6XS, UK Registered No. 785998
and Institute of Physics Publishing 2001
Dirac House, Temple Back, Bristol, BS1 6BE, UK
1
Ångstr om, Anders Jonas (1814–74)
E
NCYCLOPEDIA OF
A
STRONOMY AND
A
STROPHYSICS
Ångstr om, Anders Jonas (1814–74)
Physicist, born in Lodg o, Sweden. He was keeper of the
observatory and professor at Uppsala where he studied
heat, magnetism and optics and examined the spectra of
the Sun and auroras. His name is commemorated with
the
angstrom unit
,10
−
10
m, which is used for measuring
wavelengths of light and x-rays, and the separation of
atoms in molecules and crystals.
Copyright © Nature Publishing Group 2001
Brunel Road, Houndmills, Basingstoke, Hampshire, RG21 6XS, UK Registered No. 785998
and Institute of Physics Publishing 2001
Dirac House, Temple Back, Bristol, BS1 6BE, UK
1
61 Cygni
E
NCYCLOPEDIA OF
A
STRONOMY AND
A
STROPHYSICS
61 Cygni
The star 61 Cygni is important because of its large proper
motion, first measured at the Palermo Observatory by
Giuseppe Piazzi (1746–1826). The star became popularly
known as ‘Piazzi’s flying star’. Its measured annual proper
motion of 5.23
is still the seventh largest known, and is
the largest for a naked-eye star (apparent magnitude 4.8).
This star was also the first to have its annual parallax
reliably determined, by Friedrich Bessel (1784–1846).
Bessel’s measurement of 0.314
, made at K onigsberg with
Fraunhofer’s 6.25 inch heliometer in 1838, compares quite
well with the modern value of 0.286
. Determinations of
stellar parallax made in the same year by other observers
were far less accurate. It is the eleventh closest star, at a
distance of 11.4 light-years.
61 Cygni is also a well-known binary system, with
a period of 653.3 years. Its components are currently
separated by 30.3
at position angle 150
◦
. The primary
star 61 Cyg A is an orange dwarf, spectral type K5V,
of apparent magnitude 5.20 and absolute magnitude 7.5.
Its companion 61 Cyg B is also an orange dwarf, of
spectral type K7V, with an apparent magnitude of 6.05
and absolute magnitude 8.3. The system is reputed
to be the most extensively observed double star, some
thousands of visual observations being supplemented by
more than 34 000 photographic plates. Precise astrometric
measurements of these plates have indicated that the
system has at least one invisible component, believed to
be a planet of similar mass to Jupiter, and perhaps as many
as three, with orbital periods of between 5 and 12 years.
Copyright © Nature Publishing Group 2001
Brunel Road, Houndmills, Basingstoke, Hampshire, RG21 6XS, UK Registered No. 785998
and Institute of Physics Publishing 2001
Dirac House, Temple Back, Bristol, BS1 6BE, UK
1
Abastumani Astrophysical Observatory
E
NCYCLOPEDIA OF
A
STRONOMY AND
A
STROPHYSICS
Abastumani Astrophysical
Observatory
The Abastumani Astrophysical Observatory (AbAO)—
longitude, 42.83; latitude, 41.81 degrees—was founded in
1932. It is located in Abastumani, in the south-west part
of the Republic of Georgia, 250 km west of the capital city
Tbilisi, on the top of Mount Kanobili at 1700 m.
AbAO’s primary mission is to enable astronomers
of the former Soviet Union to carry out high-quality
observations. The average number of clear nights is
130 per year with 25% of seeings smaller than one
arcsec. At present, about 100 staff members work at the
Observatory in six departments and four laboratories. The
Observatory’s main facilities are 125 cm Ritchey–Chretien
and 70 cm meniscus telescopes.
The major research areas are accretion disks and
pulsars astrophysics, solar system cosmogony, objec-
tive prism spectroscopy, low-amplitude short-period vari-
ables, AGNs variability, solar physics, solar–terrestrial
phenomena and atmospheric physics.
For further information see
Copyright © Nature Publishing Group 2001
Brunel Road, Houndmills, Basingstoke, Hampshire, RG21 6XS, UK Registered No. 785998
and Institute of Physics Publishing 2001
Dirac House, Temple Back, Bristol, BS1 6BE, UK
1
Abbe, Ernst (1840–1905)
E
NCYCLOPEDIA OF
A
STRONOMY AND
A
STROPHYSICS
Abbe, Ernst (1840–1905)
Born in Eisenach, Grand Duchy of Saxe-Weimar-Eisenach
(now Germany), Abbe became director of the observatory
at Jena and research director of the
CARL ZEISS
optical works
in Jena. He discovered the
Abbe sine condition
, which
describes a lens that will form an image, without defects
of coma and spherical aberration. His mathematical
treatment founded the present-day science of optics.
Copyright © Nature Publishing Group 2001
Brunel Road, Houndmills, Basingstoke, Hampshire, RG21 6XS, UK Registered No. 785998
and Institute of Physics Publishing 2001
Dirac House, Temple Back, Bristol, BS1 6BE, UK
1
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