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Microlensing event in the constellation Andromeda From Wikipedia, the free encyclopedia
PA-99-N2 is a microlensing event detected in the direction of the Andromeda Galaxy in 1999.
Observation data Epoch J2000 Equinox J2000 | |
---|---|
Constellation | Andromeda |
Right ascension | 00h 44m 20.89[1]s |
Declination | +41° 28′ 44.6″[1] |
Astrometry | |
Distance | 2,200,000[2] ly (670,000[2] pc) |
Database references | |
SIMBAD | data |
Event type | Star |
---|---|
Constellation | Andromeda |
Right ascension | 00h 44m 20.89s[1] |
Declination | +41° 28′ 44.6″[1] |
Epoch | J2000 |
Distance | 2,200,000 ly (670,000 pc)[2] |
Other designations | PA 99-N2 |
One possibility for the event is that a star in the disk of M31 gravitationally lensed a red giant also in the disk. The lensing star would have a mass between 0.02 M☉ and 3.6 M☉ with the most likely value near 0.5 M☉. In this case the lens profile makes it likely[how?] that the star has a planet.[2][3]
The possible exoplanet would have a mass of 6.34 Jupiter mass. If confirmed, it would be the first exoplanet found in another galaxy.[4] A similar event was seen in 1996 when a team of astronomers discovered an anomalous fluctuation in the Twin Quasar's lightcurve that seemed to be caused by a planet approximately three Earth masses in size in the quasar's lensing galaxy YGKOW G1. (However, the results remain speculative because the chance alignment that led to its discovery will never happen again; if that exoplanet could be confirmed, it would be the most distant known planet, 4 billion ly away.)[5]
Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity | Inclination | Radius |
---|---|---|---|---|---|---|
b (unconfirmed) | 6.34 MJ | — | — | — | — | — |
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