757 Portlandia
Discovery
Discovered byJoel Hastings Metcalf
Discovery siteTaunton, Massachusetts
Discovery date30 September 1908
Designations
(757) Portlandia
1908 EJ
Orbital characteristics[1]
Epoch 31 July 2016 (JD 2457600.5)
Uncertainty parameter 0
Observation arc99.16 yr (36218 d)
Aphelion2.6327 AU (393.85 Gm)
Perihelion2.1142 AU (316.28 Gm)
2.3734 AU (355.06 Gm)
Eccentricity0.10922
3.66 yr (1335.6 d)
133.453°
0° 16m 10.38s / day
Inclination8.1694°
22.515°
44.204°
Physical characteristics
Mean radius
16.045±0.7 km
6.5837 h (0.27432 d)[1]
0.1427±0.014[1]
M
12.3 to 15.7
10.20[1]

    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.

    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

    1. 1 2 3 4 5 6 "JPL Small-Body Database Browser: 493 Griseldis (1902 JS)". Jet Propulsion Laboratory. Retrieved 5 May 2016.
    2. ↑ Schmadel, Lutz (2003), Dictionary of minor planet names, Springer, p. 72, ISBN 9783540002383
    3. ↑ https://www.facebook.com/photo.php?fbid=10206800415562318
    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.
    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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