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(Top) 1 Explanations 2 Possible exoplanet 3 References

PA-99-N2

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PA-99-N2
Observation data Epoch J2000 Equinox J2000
Constellation	Andromeda
Right ascension	00^h44^m 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

MEGA-ML 7
Event type	Star
Constellation	Andromeda
Right ascension	00^h44^m 20.89^s^[1]
Declination	+41° 28′ 44.6″^[1]
Epoch	J2000
Distance	2,200,000 ly (670,000 pc)^[2]
Other designations	PA 99-N2
[edit on Wikidata]

PA-99-N2 is a microlensing event detected in the direction of the Andromeda Galaxy in 1999.

Explanations[edit]

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]

Possible exoplanet[edit]

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]

The PA-99-N2 planetary system^[2]
Companion (in order from star)	Mass	Semimajor axis (AU)	Orbital period (days)	Eccentricity	Inclination	Radius
b (unconfirmed)	6.34 M_J	—	—	—	—	—

References[edit]

^ ^a ^b ^c ^d "MEGA-ML 7". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 3 June 2018.

^ ^a ^b ^c ^d ^e "The Extrasolar Planet Encyclopaedia — PA-99-N2 b". Extrasolar Planets Encyclopaedia. 1995. Retrieved 2017-07-30.

^ Ingrosso, G.; Paolis, F. DE; Novati, S. Calchi; Jetzer, PH.; Nucita, A. A.; Zakharov, A. F. (2012). "Detection of Exoplanets in M31 with Pixel-Lensing: The Event Pa-99-N2 Case". The Twelfth Marcel Grossmann Meeting. The Twelfth Marcel Grossmann Meeting: On Recent Developments in Theoretical and Experimental General Relativity. p. 2191. arXiv:1001.2105. Bibcode:2012mgm..conf.2191I. doi:10.1142/9789814374552_0433. ISBN 978-981-4374-51-4.

^ An, Jin H.; Evans, N. W.; Kerins, E.; Baillon, P.; Calchi Novati, S.; Carr, B. J.; Creze, M.; Giraud‐Heraud, Y.; Gould, A.; Hewett, P.; Jetzer, Ph.; Kaplan, J.; Paulin‐Henriksson, S.; Smartt, S. J.; Tsapras, Y.; Valls‐Gabaud, D. (February 2004). "The Anomaly in the Candidate Microlensing Event PA‐99‐N2". The Astrophysical Journal. 601 (2): 845–857. arXiv:astro-ph/0310457. Bibcode:2004ApJ...601..845A. doi:10.1086/380820. S2CID 8312033.

^ Govert Schilling (6 July 1996). "Do alien worlds throng faraway galaxy?". New Scientist. No. 2037.

Constellation of Andromeda

Stars

Bayer	α (Alpheratz) β (Mirach) γ (Almach) δ ε ζ η θ ι κ λ μ ν ξ (Adhil) ο π ρ σ τ υ (Titawin) φ χ ψ ω A b c υ Per (Nembus)
Flamsteed	2 3 4 5 6 7 8 9 10 11 12 13 14 (Veritate) 15 18 22 23 26 28 32 36 39 41 44 45 47 55 56 58 59 63 64 65 66 6 Per
Variable	R T U W Z RT RV RX SU SW TU TW WZ XZ AB AC AD AE AF AR BM BX CC CG CN DS DX EG ET EU FF GO GP GQ GX GR GY HH HN IW KK KX KZ LL LN LP LQ OP OS OU PX PY QR QV QX V385 V428 V439 V455 V529 V807
HR	1 40 56 78 104 122 134 178 275 282 283 289 379 410 483 687 746 748 8884 8925 8950 8962 8973 9011 9074 9075 9105
HD	16175 (Buna) 222155
Other	3XMM J004232.1+411314 ADS 48 HAT-P-6 (Sterrennacht) HAT-P-16 HAT-P-19 HAT-P-28 M31-RV KELT-1 NGC 44 NGC 82 NGC 84 NGC 91 NGC 162 NGC 464 Qatar-3 Qatar-4 PA-99-N2 WASP-1 WISE 0146+4234 WISE J0005+3737 WISE J004945.61+215120.0

Other

NGC

7662

Galaxies

Messier	32 110
NGC	5 11 13 19 20 21 27 39 43 48 49 51 67 68 69 70 71 72 74 76 79 80 81 83 85 86 90 93 94 96 97 108 109 112 140 149 160 169 181 183 184 214 218 226 228 229 233 243 252 258 260 262 280 304 317 389 393 404 425 431 477 512 513 523 528 529 531 536 542 561 605 620 668 679 687 700 703 704 705 708 709 710 712 714 717 721 732 753 759 801 812 834 891 906 910 911 912 913 920 937 980 995 996 999 1000 7640 7836
Numbered	I II III IV V VIII IX X XI XVIII XIX XXI
Other	3C 66A 3C 66B Andromeda Galaxy Arp 273 Donatiello I UGC 1840

Galaxy clusters

Astronomical events