GD 66
Encyclopedia
GD 66 or V361 Aurigae is a 0.64 solar mass pulsating white dwarf
star located 170 light years from Earth in the Auriga constellation. The estimated cooling age of the white dwarf is 500 million years. Models of the relationship between the initial mass of a star and its final mass as a white dwarf star suggest that when the star was on the main sequence
it had a mass approximately 2.5 times that of the Sun
, which implies its lifetime was around 830 million years. The total age of the star is thus estimated to be in the range 1.2 to 1.7 billion years.
The star is a pulsating white dwarf
of type DAV, with an extremely stable period. Small variations in the phase of pulsation suggest that the star is moving in a small circle due to the gravitational pull of a smaller unseen body. This method is similar to that used to discover Pulsar Planet
s, except that the observations were in visible light instead of radio waves. The planet has not yet completed a full orbit during the time of the observations, and only one turning point
in the observed-computed time curve has been observed, which means the planet's parameters are poorly-constrained. The best fit circular orbit has a period of 5.69 years, with a minimum planet mass 2.36 times the mass of Jupiter
(note that the measured quantities only allow the product
of the planet's mass with the sine
of the orbit's inclination
to be discovered). Observations with the Spitzer Space Telescope
failed to directly detect the planet, which puts an upper limit on the mass of 5–6 Jupiter masses.
Pulsating white dwarf
A pulsating white dwarf is a white dwarf star whose luminosity varies due to non-radial gravity wave pulsations within itself. Known types of pulsating white dwarfs include DAV, or ZZ Ceti, stars, with hydrogen-dominated atmospheres and the spectral type DA, pp. 891, 895; DBV, or V777 Her,...
star located 170 light years from Earth in the Auriga constellation. The estimated cooling age of the white dwarf is 500 million years. Models of the relationship between the initial mass of a star and its final mass as a white dwarf star suggest that when the star was on the main sequence
Main sequence
The main sequence is a continuous and distinctive band of stars that appears on plots of stellar color versus brightness. These color-magnitude plots are known as Hertzsprung–Russell diagrams after their co-developers, Ejnar Hertzsprung and Henry Norris Russell...
it had a mass approximately 2.5 times that 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...
, which implies its lifetime was around 830 million years. The total age of the star is thus estimated to be in the range 1.2 to 1.7 billion years.
The star is a pulsating white dwarf
Pulsating white dwarf
A pulsating white dwarf is a white dwarf star whose luminosity varies due to non-radial gravity wave pulsations within itself. Known types of pulsating white dwarfs include DAV, or ZZ Ceti, stars, with hydrogen-dominated atmospheres and the spectral type DA, pp. 891, 895; DBV, or V777 Her,...
of type DAV, with an extremely stable period. Small variations in the phase of pulsation suggest that the star is moving in a small circle due to the gravitational pull of a smaller unseen body. This method is similar to that used to discover Pulsar Planet
Pulsar planet
Pulsar planets are planets that are found orbiting pulsars, or rapidly rotating neutron stars. The first such planet to be discovered was around a millisecond pulsar and was the first extrasolar planet to be confirmed as discovered.-Pulsar planets:...
s, except that the observations were in visible light instead of radio waves. The planet has not yet completed a full orbit during the time of the observations, and only one turning point
Stationary point
In mathematics, particularly in calculus, a stationary point is an input to a function where the derivative is zero : where the function "stops" increasing or decreasing ....
in the observed-computed time curve has been observed, which means the planet's parameters are poorly-constrained. The best fit circular orbit has a period of 5.69 years, with a minimum planet mass 2.36 times the mass of Jupiter
Jupiter
Jupiter is the fifth planet from the Sun and the largest planet within the Solar System. It is a gas giant with mass one-thousandth that of the Sun but is two and a half times the mass of all the other planets in our Solar System combined. Jupiter is classified as a gas giant along with Saturn,...
(note that the measured quantities only allow the product
Product (mathematics)
In mathematics, a product is the result of multiplying, or an expression that identifies factors to be multiplied. The order in which real or complex numbers are multiplied has no bearing on the product; this is known as the commutative law of multiplication...
of the planet's mass with the sine
Sine
In mathematics, the sine function is a function of an angle. In a right triangle, sine gives the ratio of the length of the side opposite to an angle to the length of the hypotenuse.Sine is usually listed first amongst the trigonometric functions....
of the orbit's inclination
Inclination
Inclination in general is the angle between a reference plane and another plane or axis of direction.-Orbits:The inclination is one of the six orbital parameters describing the shape and orientation of a celestial orbit...
to be discovered). Observations with the Spitzer Space Telescope
Spitzer Space Telescope
The Spitzer Space Telescope , formerly the Space Infrared Telescope Facility is an infrared space observatory launched in 2003...
failed to directly detect the planet, which puts an upper limit on the mass of 5–6 Jupiter masses.
External links
- V361 Aurigae Catalog
- WD 0517+307 Catalog
- Image GD 66