MOA-2009-BLG-387L

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MOA-2009-BLG-387L
Sagittarius IAU.svg
Constellation Sagittarius. MOA-2009-BLG-387L is located just to the right of "The Teapot".
Observation data
Epoch J2000       Equinox J2000
Constellation Sagittarius
Right ascension  17h 53m 51s
Declination −33° 59′ 25″
Apparent magnitude  (V)18.35 (± 0.03) [1]
Characteristics
Spectral type M [2]
Astrometry
Distance 5700 (± 2200) [2]   pc
Details
Mass 0.19 +0.3
−0.12 [2]   M☉
Database references
SIMBAD data

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 both the mass and distance. The star drew the attention of astronomers when it became the lens of gravitational microlensing event MOA-2009-BLG-387L, in which it eclipsed a background star and created distorted caustics, an envelope of reflected or refracted light rays. Analysis of the caustic events and of follow-up observational data led to the planet's discovery, which was reported in February 2011.

Contents

Observational history

The Very Large Telescope Array, which was used to conduct follow-up observations. Aerial View of the VLTI with Tunnels Superimposed.jpg
The Very Large Telescope Array, which was used to conduct follow-up observations.

On July 24, 2009, the Microlensing Observations in Astrophysics collaboration (MOA) detected the star MOA-2009-BLG-387L eclipsing a background star in a microlensing event that was named MOA-2009-BLG-387. In a process called gravitational microlensing, the star MOA-2009-BLG-387L became a lens that created two distorted caustic images. In the case of the microlensing event MOA-2009-BLG-387, these caustics produced a series of small "resonating" diffractions; such resonant-caustic events are valued because they tend to yield more information about an orbiting planet. [1]

The first caustic event was detected by the South African Astronomical Observatory (SAAO) on July 24, 2009. An alert was issued, which attracted many to cover the caustic event; as such, the end of the first caustic event was well-documented. [1] The microlensing event's second caustic event was seven days later, an unusually long middle period for planetary microlensing events. [1] An alert brought three different telescopes at SAAO and telescopes at ten different observatories to focus on the event.

Follow-up observations on the star MOA-2009-BLG-387L using the NACO imager at the Very Large Telescope array successfully distinguished the star's mass. The collected data from VLT and from observations during the microlensing event was run through a series of models and analyzed. An orbiting planetary body larger than Jupiter (or of a similar size, given uncertainties) was discovered. The discovery of the planet was reported on February 21, 2011 in the journal Astronomy and Astrophysics . [1]

Characteristics

MOA-2009-BLG-387L is an M-type red dwarf in the Sagittarius constellation. It is estimated to be 5700 parsecs (18,591 light years) away, although uncertainty has led the discovering team to place the confidence intervals at ± 2200 parsecs (7,176 light years); in other words, although the distance of MOA-2009-BLG-387L from Earth is best placed at 5700 parsecs, astronomers can only be 90% certain that it is somewhere between 3,500 and 7,900 parsecs away. [2] Likewise, although MOA-2009-BLG-387L's mass has been estimated at 0.19 times that of the Sun, [2] the confidence intervals remain large (+0.3
−0.12), as uncertainty in the mass of the planet places its true mass between 0.07 and 0.49 times the mass of the Sun. This covers the entirety of the range of masses known in red dwarfs. [1]

The ratio between planet MOA-2009-BLG-387Lb's mass to that of its host star has been found with accuracy. However, because the host star's characteristics are not as well-constrained, the planet's characteristics are not well-constrained either. [1] The inability to constrain many of MOA-2009-BLG-387L's characteristics is a consequence of the fact that the star acted as the lens in the microlensing event, which compromised the ability to collect most of the star's stellar parameters. [1]

Planetary system

MOA-2009-BLG-387Lb is the only known exoplanet in the orbit of host star MOA-2009-BLG-387L. The planet is estimated to be 2.6 times the mass of Jupiter. [2] However, because knowledge of the exact parameters of the planet are tied to the host star's parameters, and the host star's parameters are not well-constrained, uncertainty places MOA-2009-BLG-387Lb's mass between 1.0 and 6.7 times that of Jupiter. [1] The planet is estimated to orbit its host star every 1970 days at a distance of 1.8 AU, some 1.8 times the mean distance between Earth and the Sun. Uncertainty broadens the mean distance to between 1.1 and 2.7 AU. [2]

The MOA-2009-BLG-387L planetary system
Companion
(in order from star)		 Mass Semimajor axis
(AU)		 Orbital period
(days)		 Eccentricity Inclination Radius
b 2.6  MJ 1.81970?——

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MOA-2008-BLG-310Lb is an extrasolar planet which orbits probably the late K-type star MOA-2008-BLG-310L, located at least 20000 light years away in the constellation Scorpius. This planet has mass 23% of Jupiter or 77% of Saturn and orbits at 1.25 AU from the star. This planet was discovered by using the gravitational microlensing method on August 4, 2009. As it is typical for exoplanets detected by microlensing method, the orbital period and eccentricity are not determined.

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MOA-2009-BLG-387Lb extrasolar planet

MOA-2009-BLG-387Lb is an exoplanet 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.

MOA-2010-BLG-477L is a K-type star with about 0.67 times the mass of the Sun, in the main-sequence phase of its stellar evolution. Overall, very little is known about this star, with very poor constrains on its projected characteristics due to One extrasolar planet, with a mass greater than that of Jupiter, has been discovered orbiting the star at a distance of roughly 2 AU. The planet was detected by means of microlensing, where gravitational lensing as the planet and its host star pass in front of a background star causes a temporary flare in the amount of light observed, allowing the planet's existence to be known.

OGLE-2014-BLG-0124Lb is one of the farthest planets that we know of today. It is approximately 13,000 light years away, located near the center of the galaxy. The planet was discovered using a technique called microlensing. In this case it took 150 days. Two telescopes are used to detect the planet and the time difference between identification by each telescope is used to calculate the distance to the planet. This also contributes to determining the mass of the planet which is about half of Jupiter's. The planet orbits a star with a mass of 0.7 solar masses and is 3.1 AUs from it.

OGLE-2016-BLG-1190Lb Exoplanet

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References

  1. 1 2 3 4 5 6 7 8 9 Batista, V.; Gould, A. (2011). "MOA-2009-BLG-387Lb: A massive planet orbiting an M dwarf". Astronomy and Astrophysics . European Southern Observatory. 529: A102. arXiv: 1102.0558 . Bibcode:2011yCat..35290102B. doi:10.1051/0004-6361/201016111. S2CID   20954769.
  2. 1 2 3 4 5 6 7 Jean Schneider (2011). "Notes for star MOA-2009-BLG-387L". Extrasolar Planets Encyclopaedia . Retrieved 21 May 2011.

Coordinates: Celestia.png 17h 53m 51s, −33° 59′ 25″

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