757 Portlandia

757 Portlandia
Discovery
Discovered by	Joel Hastings Metcalf
Discovery site	Taunton, Massachusetts
Discovery date	30 September 1908
Designations
MPC designation	(757) Portlandia
Alternative designations	1908 EJ
Orbital characteristics
	Epoch 31 July 2016 (JD 2457600.5)
	Uncertainty parameter 0
Observation arc	99.16 yr (36218 d)
Aphelion	2.6327 AU (393.85 Gm)
Perihelion	2.1142 AU (316.28 Gm)
Semi-major axis	2.3734 AU (355.06 Gm)
Eccentricity	0.10922
Orbital period (sidereal)	3.66 yr (1335.6 d)
Mean anomaly	133.453°
Mean motion	0° 16m 10.38s / day
Inclination	8.1694°
Longitude of ascending node	22.515°
Argument of perihelion	44.204°
Physical characteristics
Mean radius	16.045±0.7 km
Synodic rotation period	6.5837 h (0.27432 d)
Geometric albedo	0.1427±0.014
Spectral type	M
Apparent magnitude	12.3 to 15.7
Absolute magnitude (H)	10.20

757 Portlandia is a main-belt asteroid 32 km in diameter.^[1] It was discovered on 30 September 1908 from Taunton, Massachusetts by the amateur American astronomer Joel E. Metcalf. The asteroid was named for the city of Portland, Maine, where Hastings was a church minister at the time.^[2] In November 2015, amateur astronomers captured it with images of comet 67P/Churyumov–Gerasimenko.^[3] Portlandia came to opposition in March 2016 at apparent magnitude 13.2.^{[citation needed]}

This body is orbiting at a distance of 2.37 AU with a period of 3.66 years and an eccentricity of 0.109. The orbital plane is inclined at an angle of 8.2° to the plane of the ecliptic.^[1] 757 Portlandia is classified as an X-type asteroid and is a core member of the proposed Athor asteroid family, named after 161 Athor. This asteroid spans a girth of 32.89±0.24 km and is rotating with a period of 6.58 hours.^[4] During 2003, the asteroid was observed occulting a star. The resulting chords were used to determine a diameter estimate of 36.7 km.^[5]

References[]

^ ^a ^b ^c ^d ^e ^f "JPL Small-Body Database Browser: 493 Griseldis (1902 JS)". Jet Propulsion Laboratory. Retrieved 5 May 2016.
^ Schmadel, Lutz (2003), Dictionary of minor planet names, Springer, p. 72, ISBN 9783540002383
^ https://www.facebook.com/photo.php?fbid=10206800415562318
^ Delbo, Marco; et al. (April 2019), "Ancient and primordial collisional families as the main sources of X-type asteroids of the inner main belt", Astronomy & Astrophysics, 624: 21, arXiv:1902.01633, Bibcode:2019A&A...624A..69D, doi:10.1051/0004-6361/201834745, S2CID 118918763, A69.
^ Shevchenko, Vasilij G.; Tedesco, Edward F. (September 2006), "Asteroid albedos deduced from stellar occultations", Icarus, 184 (1): 211–220, Bibcode:2006Icar..184..211S, doi:10.1016/j.icarus.2006.04.006.

External links[]

757 Portlandia at AstDyS-2, Asteroids—Dynamic Site
- Ephemeris · Observation prediction · Orbital info · Proper elements · Observational info
757 Portlandia at the JPL Small-Body Database
- Close approach · Discovery · Ephemeris · Orbit diagram · Orbital elements · Physical parameters

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[jpldata-1] ^ ^a ^b ^c ^d ^e ^f "JPL Small-Body Database Browser: 493 Griseldis (1902 JS)". Jet Propulsion Laboratory. Retrieved 5 May 2016.

[Schmadel2003-2] Schmadel, Lutz (2003), Dictionary of minor planet names, Springer, p. 72, ISBN 9783540002383

[3] ttps://www.facebook.com/photo.php?fbid=10206800415562318

[Delbo2019-4] Delbo, Marco; et al. (April 2019), "Ancient and primordial collisional families as the main sources of X-type asteroids of the inner main belt", Astronomy & Astrophysics, 624: 21, arXiv:1902.01633, Bibcode:2019A&A...624A..69D, doi:10.1051/0004-6361/201834745, S2CID 118918763, A69.

[Shevchenko_Tedesco_2006-5] Shevchenko, Vasilij G.; Tedesco, Edward F. (September 2006), "Asteroid albedos deduced from stellar occultations", Icarus, 184 (1): 211–220, Bibcode:2006Icar..184..211S, doi:10.1016/j.icarus.2006.04.006.

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