MOA-2009-BLG-387Lb
Encyclopedia
MOA-2009-BLG-387Lb is a planet in the orbit of the red dwarf MOA-2009-BLG-387L
. Its discovery was announced on February 21, 2011, making it the eleventh planet discovered using gravitational microlensing
. The planet is thought to be over twice the mass of Jupiter and to have an orbit 80 percent larger than that of Earth's, lasting approximately 1,970 days. However, its exact characteristics are difficult to constrain because the characteristics of the host star are not well known.
event detected by the Microlensing Observations in Astrophysics
collaboration on July 24, 2009, which searches and documents chance and brief alignments of stars with other stars or objects; such alignments cause a gravitational lens
effect, which bends light and causes distorted, but magnified, images that can be interpreted. The detection of two caustics
were logged over the next few days by the South African Astronomical Observatory
, the Perth Observatory
, and the Canopus Hill Observatory
in Tasmania, with a separation of about seven days between caustic events.
On June 7, 2010, long after the microlensing event had subsided, the science teams studying the star used the NACO adaptive optics
facility at the Very Large Telescope
in Chile to determine the actual apparent magnitude
of the star that microlensed its background star, hoping to compare it to the magnitude of the star measured during the microlensing event. A discrepancy was found, a discrepancy that may have been a result of either error or of a planetary body. Interpretation of follow-up observations led to the planet's confirmation. The ratio between the planet's mass and its host star's mass is well-constrained, but a large interval of uncertainty exists because the host star's mass is known within a large confidence interval
that spans the mass of all red dwarf
stars.
The discovery of the planet MOA-2009-BLG-387Lb was published on February 21, 2011 in the journal Astronomy and Astrophysics
by the European Southern Observatory
.
, with an estimated mass
2.6 times that of Jupiter's and an estimated mean distance of 1.8 AU
from its host star. It has an orbital period
of approximately 1970 days. Although the mass and mean distance of MOA-2009-BLG-387Lb is estimated, the confidence interval
s are very large, indicating that there is a large uncertainty present. These uncertainties are largely due to how the exact parameters of the host star are not known.
The planet is the only one known to be in the orbit of the star MOA-2009-BLG-387L
, which is an M-type dwarf star that has a mass
that is approximately 0.19 times that of the Sun. The star is located at an estimated 5700 parsec
s (18,591 light years) from the Earth. The star is named for the Microlensing Observations in Astrophysics
group, which saw the star as a gravitational microlensing
event in 2009 and combed the data in hope of discovering a planet.
MOA-2009-BLG-387L
MOA-2009-BLG-387L is a red dwarf in the Sagittarius constellation that is host to the planet MOA-2009-BLG-387Lb. The star is estimated to be nearly 20,000 light years away and approximately one fifth the mass of the Sun, although large confidence intervals exist, reflecting the uncertainties in...
. Its discovery was announced on February 21, 2011, making it the eleventh planet discovered using gravitational microlensing
Gravitational microlensing
Gravitational microlensing is an astronomical phenomenon due to the gravitational lens effect. It can be used to detect objects ranging from the mass of a planet to the mass of a star, regardless of the light they emit. Typically, astronomers can only detect bright objects that emit lots of light ...
. The planet is thought to be over twice the mass of Jupiter and to have an orbit 80 percent larger than that of Earth's, lasting approximately 1,970 days. However, its exact characteristics are difficult to constrain because the characteristics of the host star are not well known.
Discovery
MOA-2009-BLG-387 was a gravitational microlensingGravitational microlensing
Gravitational microlensing is an astronomical phenomenon due to the gravitational lens effect. It can be used to detect objects ranging from the mass of a planet to the mass of a star, regardless of the light they emit. Typically, astronomers can only detect bright objects that emit lots of light ...
event detected by the Microlensing Observations in Astrophysics
Microlensing Observations in Astrophysics
Microlensing Observations in Astrophysics is a collaborative project between researchers in New Zealand and Japan, led by Professor Yasushi Muraki of Nagoya University. They use microlensing to observe dark matter, extra-solar planets, and stellar atmospheres from the Southern Hemisphere...
collaboration on July 24, 2009, which searches and documents chance and brief alignments of stars with other stars or objects; such alignments cause a gravitational lens
Gravitational lens
A gravitational lens refers to a distribution of matter between a distant source and an observer, that is capable of bending the light from the source, as it travels towards the observer...
effect, which bends light and causes distorted, but magnified, images that can be interpreted. The detection of two caustics
Caustic (optics)
In optics, a caustic or caustic network is the envelope of light rays reflected or refracted by a curved surface or object, or the projection of that envelope of rays on another surface. The caustic is a curve or surface to which each of the light rays is tangent, defining a boundary of an...
were logged over the next few days by the South African Astronomical Observatory
South African Astronomical Observatory
South African Astronomical Observatory is the national center for optical and infrared astronomy in South Africa. It was established in 1972. The observatory is run by the National Research Foundation of South Africa. The facility's function is to conduct research in astronomy and astrophysics...
, the Perth Observatory
Perth Observatory
The Perth Observatory is the name of two astronomical observatories located in Western Australia.-First Perth Observatory:The original Perth Observatory was constructed in 1896 and was officially opened in 1900 by John Forrest, the first premier of Western Australia. The observatory was located at...
, and the Canopus Hill Observatory
Canopus Hill Observatory
The Canopus Hill Observatory is an optical astronomy observatory belonging to the University of Tasmania , It is located approximately 12 km from Hobart in Tasmania, Australia and is a host of Canopus 1 m telescope...
in Tasmania, with a separation of about seven days between caustic events.
On June 7, 2010, long after the microlensing event had subsided, the science teams studying the star used the NACO adaptive optics
Adaptive optics
Adaptive optics is a technology used to improve the performance of optical systems by reducing the effect of wavefront distortions. It is used in astronomical telescopes and laser communication systems to remove the effects of atmospheric distortion, and in retinal imaging systems to reduce the...
facility at the Very Large Telescope
Very Large Telescope
The Very Large Telescope is a telescope operated by the European Southern Observatory on Cerro Paranal in the Atacama Desert of northern Chile. The VLT consists of four individual telescopes, each with a primary mirror 8.2m across, which are generally used separately but can be used together to...
in Chile to determine the actual 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 the star that microlensed its background star, hoping to compare it to the magnitude of the star measured during the microlensing event. A discrepancy was found, a discrepancy that may have been a result of either error or of a planetary body. Interpretation of follow-up observations led to the planet's confirmation. The ratio between the planet's mass and its host star's mass is well-constrained, but a large interval of uncertainty exists because the host star's mass is known within a large confidence interval
Confidence interval
In statistics, a confidence interval is a particular kind of interval estimate of a population parameter and is used to indicate the reliability of an estimate. It is an observed interval , in principle different from sample to sample, that frequently includes the parameter of interest, if the...
that spans the mass of all red dwarf
Red dwarf
According to the Hertzsprung-Russell diagram, a red dwarf star is a small and relatively cool star, of the main sequence, either late K or M spectral type....
stars.
The discovery of the planet MOA-2009-BLG-387Lb was published on February 21, 2011 in the journal Astronomy and Astrophysics
Astronomy and Astrophysics
* Astronomy and Astrophysics has a 2010 impact factor of 4.410.-See also:*The Astronomy and Astrophysics Review*Advanced Satellite for Cosmology and Astrophysics*Astronomy & Geophysics*Astronomical Journal*Astrophysical Journal...
by the European Southern Observatory
European Southern Observatory
The European Southern Observatory is an intergovernmental research organisation for astronomy, supported by fifteen countries...
.
Characteristics
MOA-2009-BLG-387Lb is a gas giantGas giant
A gas giant is a large planet that is not primarily composed of rock or other solid matter. There are four gas giants in the Solar System: Jupiter, Saturn, Uranus, and Neptune...
, with an estimated mass
Jupiter mass
Jupiter mass , is the unit of mass equal to the total mass of the planet Jupiter . Jupiter mass is used to describe masses of the gas giants, such as the outer planets and extrasolar planets. It is also used in describing brown dwarfs....
2.6 times that of Jupiter's and an estimated mean distance of 1.8 AU
Astronomical unit
An astronomical unit is a unit of length equal to about or approximately the mean Earth–Sun distance....
from its host star. It has an orbital period
Orbital period
The orbital period is the time taken for a given object to make one complete orbit about another object.When mentioned without further qualification in astronomy this refers to the sidereal period of an astronomical object, which is calculated with respect to the stars.There are several kinds of...
of approximately 1970 days. Although the mass and mean distance of MOA-2009-BLG-387Lb is estimated, the confidence interval
Confidence interval
In statistics, a confidence interval is a particular kind of interval estimate of a population parameter and is used to indicate the reliability of an estimate. It is an observed interval , in principle different from sample to sample, that frequently includes the parameter of interest, if the...
s are very large, indicating that there is a large uncertainty present. These uncertainties are largely due to how the exact parameters of the host star are not known.
The planet is the only one known to be in the orbit of the star MOA-2009-BLG-387L
MOA-2009-BLG-387L
MOA-2009-BLG-387L is a red dwarf in the Sagittarius constellation that is host to the planet MOA-2009-BLG-387Lb. The star is estimated to be nearly 20,000 light years away and approximately one fifth the mass of the Sun, although large confidence intervals exist, reflecting the uncertainties in...
, which is an M-type dwarf star that has a mass
Solar mass
The solar mass , , is a standard unit of mass in astronomy, used to indicate the masses of other stars and galaxies...
that is approximately 0.19 times that of the Sun. The star is located at an estimated 5700 parsec
Parsec
The parsec is a unit of length used in astronomy. It is about 3.26 light-years, or just under 31 trillion kilometres ....
s (18,591 light years) from the Earth. The star is named for the Microlensing Observations in Astrophysics
Microlensing Observations in Astrophysics
Microlensing Observations in Astrophysics is a collaborative project between researchers in New Zealand and Japan, led by Professor Yasushi Muraki of Nagoya University. They use microlensing to observe dark matter, extra-solar planets, and stellar atmospheres from the Southern Hemisphere...
group, which saw the star as a gravitational microlensing
Gravitational microlensing
Gravitational microlensing is an astronomical phenomenon due to the gravitational lens effect. It can be used to detect objects ranging from the mass of a planet to the mass of a star, regardless of the light they emit. Typically, astronomers can only detect bright objects that emit lots of light ...
event in 2009 and combed the data in hope of discovering a planet.