Zeta Leporis
Encyclopedia
Zeta Leporis is a white main sequence star
approximately 70 light-year
s away in the constellation
of Lepus
. The star is suspected of being a spectroscopic binary star system, but this is yet to be confirmed. In 2001, an asteroid belt
was confirmed to orbit the star.
star with an apparent magnitude
of 3.5. It is a white main sequence star
(not to be confused with a white dwarf
) of the spectral type of "A2-3Vann". The star is thought to have about two times the mass
of the Sun
, along with 1.7 times the radius
, and 15 times the luminosity
. The star appears to be a very young star, probably around 100 million years old, but could be anywhere between 50 and 500 million years old. The star was suggested to be a spectroscopic binary star. But because this secondary star was not confirmed, there is no data on the star.
portion of the electromagnetic spectrum
, the InfraRed Astronomical Satellite
was used to identify dust orbiting this star. The region containing the dust was constricted to a radius of 12.2 Astronomical units, or just over twelve times the distance from the Earth
to the Sun.
By 2001, the Long Wavelength Spectrometer at the Keck Observatory on Mauna Kea
, Hawaii
, was used more accurately to constrain the radius of the dust. It was found to lie within a 5.4 AU radius. The temperature of the dust was estimated as about 340 K. Based on heating from the star, this could place the grains as close as 2.5 AU from Zeta Leporis.
It is now believed that the dust is coming from a massive asteroid belt
in orbit around Zeta Leporis, making it the first extra-solar asteroid belt to be discovered. The estimated mass of the belt is about 200 times the total in our own asteroid belt, or 4 × 1023 kg. (For comparison, that is more than half the total mass of our Moon
.) Astronomers Christine Chen and professor Michael Jura found that the dust contained within this belt should have fallen into the star within 20,000 years, a much shorter time period than Zeta Leporis' estimated age, suggesting that some mechanism must be replenishing the belt. The belt's age is estimated to be 3 × 108 years.
s (4.17 light-year
s) from the Sun about 861,000 years ago. García-Sánchez 2001 suggested that the star passed 1.64 parsecs (5.34 light-years) from the Sun about 1 million years ago.
White main sequence star
An A-type main-sequence star is a main-sequence star of spectral type A and luminosity class V. These stars have spectra which are defined by strong hydrogen Balmer absorption lines...
approximately 70 light-year
Light-year
A light-year, also light year or lightyear is a unit of length, equal to just under 10 trillion kilometres...
s away in the constellation
Constellation
In modern astronomy, a constellation is an internationally defined area of the celestial sphere. These areas are grouped around asterisms, patterns formed by prominent stars within apparent proximity to one another on Earth's night sky....
of Lepus
Lepus (constellation)
Lepus is a constellation lying just south of the celestial equator, immediately south of Orion. Its name is Latin for hare. Although the hare does not represent any particular figure in Greek mythology, Lepus was one of the 48 constellations listed by the 2nd century astronomer Ptolemy, and it...
. The star is suspected of being a spectroscopic binary star system, but this is yet to be confirmed. In 2001, an asteroid belt
Asteroid belt
The asteroid belt is the region of the Solar System located roughly between the orbits of the planets Mars and Jupiter. It is occupied by numerous irregularly shaped bodies called asteroids or minor planets...
was confirmed to orbit the star.
Stellar components
Zeta Leporis is a naked eyeNaked eye
The naked eye is a figure of speech referring to human visual perception unaided by a magnifying or light-collecting optical device, such as a telescope or microscope. Vision corrected to normal acuity using corrective lenses is considered "naked"...
star with an apparent magnitude
Apparent magnitude
The apparent magnitude of a celestial body is a measure of its brightness as seen by an observer on Earth, adjusted to the value it would have in the absence of the atmosphere...
of 3.5. It is a white main sequence star
White main sequence star
An A-type main-sequence star is a main-sequence star of spectral type A and luminosity class V. These stars have spectra which are defined by strong hydrogen Balmer absorption lines...
(not to be confused with a white dwarf
White dwarf
A white dwarf, also called a degenerate dwarf, is a small star composed mostly of electron-degenerate matter. They are very dense; a white dwarf's mass is comparable to that of the Sun and its volume is comparable to that of the Earth. Its faint luminosity comes from the emission of stored...
) of the spectral type of "A2-3Vann". The star is thought to have about two times the mass
Mass
Mass can be defined as a quantitive measure of the resistance an object has to change in its velocity.In physics, mass commonly refers to any of the following three properties of matter, which have been shown experimentally to be equivalent:...
of the Sun
Sun
The Sun is the star at the center of the Solar System. It is almost perfectly spherical and consists of hot plasma interwoven with magnetic fields...
, along with 1.7 times the radius
Radius
In classical geometry, a radius of a circle or sphere is any line segment from its center to its perimeter. By extension, the radius of a circle or sphere is the length of any such segment, which is half the diameter. If the object does not have an obvious center, the term may refer to its...
, and 15 times the luminosity
Luminosity
Luminosity is a measurement of brightness.-In photometry and color imaging:In photometry, luminosity is sometimes incorrectly used to refer to luminance, which is the density of luminous intensity in a given direction. The SI unit for luminance is candela per square metre.The luminosity function...
. The star appears to be a very young star, probably around 100 million years old, but could be anywhere between 50 and 500 million years old. The star was suggested to be a spectroscopic binary star. But because this secondary star was not confirmed, there is no data on the star.
Asteroid belt
In 1983, based on radiation in the infraredInfrared
Infrared light is electromagnetic radiation with a wavelength longer than that of visible light, measured from the nominal edge of visible red light at 0.74 micrometres , and extending conventionally to 300 µm...
portion of the electromagnetic spectrum
Electromagnetic spectrum
The electromagnetic spectrum is the range of all possible frequencies of electromagnetic radiation. The "electromagnetic spectrum" of an object is the characteristic distribution of electromagnetic radiation emitted or absorbed by that particular object....
, the InfraRed Astronomical Satellite
IRAS
The Infrared Astronomical Satellite was the first-ever space-based observatory to perform a survey of the entire sky at infrared wavelengths....
was used to identify dust orbiting this star. The region containing the dust was constricted to a radius of 12.2 Astronomical units, or just over twelve times the distance from the Earth
Earth
Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...
to the Sun.
By 2001, the Long Wavelength Spectrometer at the Keck Observatory on Mauna Kea
Mauna Kea
Mauna Kea is a volcano on the island of Hawaii. Standing above sea level, its peak is the highest point in the state of Hawaii. However, much of the mountain is under water; when measured from its oceanic base, Mauna Kea is over tall—significantly taller than Mount Everest...
, Hawaii
Hawaii
Hawaii is the newest of the 50 U.S. states , and is the only U.S. state made up entirely of islands. It is the northernmost island group in Polynesia, occupying most of an archipelago in the central Pacific Ocean, southwest of the continental United States, southeast of Japan, and northeast of...
, was used more accurately to constrain the radius of the dust. It was found to lie within a 5.4 AU radius. The temperature of the dust was estimated as about 340 K. Based on heating from the star, this could place the grains as close as 2.5 AU from Zeta Leporis.
It is now believed that the dust is coming from a massive asteroid belt
Asteroid belt
The asteroid belt is the region of the Solar System located roughly between the orbits of the planets Mars and Jupiter. It is occupied by numerous irregularly shaped bodies called asteroids or minor planets...
in orbit around Zeta Leporis, making it the first extra-solar asteroid belt to be discovered. The estimated mass of the belt is about 200 times the total in our own asteroid belt, or 4 × 1023 kg. (For comparison, that is more than half the total mass of our Moon
Moon
The Moon is Earth's only known natural satellite,There are a number of near-Earth asteroids including 3753 Cruithne that are co-orbital with Earth: their orbits bring them close to Earth for periods of time but then alter in the long term . These are quasi-satellites and not true moons. For more...
.) Astronomers Christine Chen and professor Michael Jura found that the dust contained within this belt should have fallen into the star within 20,000 years, a much shorter time period than Zeta Leporis' estimated age, suggesting that some mechanism must be replenishing the belt. The belt's age is estimated to be 3 × 108 years.
Solar encounter
Bobylev's calculations from 2010 suggest that this star passed as close as 1.28 parsecParsec
The parsec is a unit of length used in astronomy. It is about 3.26 light-years, or just under 31 trillion kilometres ....
s (4.17 light-year
Light-year
A light-year, also light year or lightyear is a unit of length, equal to just under 10 trillion kilometres...
s) from the Sun about 861,000 years ago. García-Sánchez 2001 suggested that the star passed 1.64 parsecs (5.34 light-years) from the Sun about 1 million years ago.