Astronomy:757 Portlandia
| Discovery | |
|---|---|
| Discovered by | Joel Hastings Metcalf |
| Discovery site | Taunton, Massachusetts |
| Discovery date | 30 September 1908 |
| Designations | |
| (757) Portlandia | |
| 1908 EJ | |
| Orbital characteristics[1] | |
| Epoch 31 July 2016 (JD 2457600.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 99.16 yr (36218 d) |
| |{{{apsis}}}|helion}} | 2.6327 astronomical unit|AU (393.85 Gm) |
| |{{{apsis}}}|helion}} | 2.1142 AU (316.28 Gm) |
| 2.3734 AU (355.06 Gm) | |
| Eccentricity | 0.10922 |
| Orbital period | 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° |
| 44.204° | |
| Physical characteristics | |
| Mean radius | 16.045±0.7 km |
| Rotation period | 6.5837 h (0.27432 d)[1] |
| Geometric albedo | 0.1427±0.014[1] |
| M | |
| Apparent magnitude | 12.3 to 15.7 |
| Absolute magnitude (H) | 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.[citation needed]
This body is orbiting at a distance of 2.37 astronomical unit|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
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 "JPL Small-Body Database Browser: 493 Griseldis (1902 JS)". Jet Propulsion Laboratory. https://ssd.jpl.nasa.gov/sbdb.cgi?sstr=757;cad=1.
- ↑ Schmadel, Lutz (2003), Dictionary of minor planet names, Springer, p. 72, ISBN 9783540002383, https://books.google.com/books?id=VoJ5nUyIzCsC&pg=PA72
- ↑ https://www.facebook.com/photo.php?fbid=10206800415562318 [user-generated source]
- ↑ 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, doi:10.1051/0004-6361/201834745, A69, Bibcode: 2019A&A...624A..69D.
- ↑ Shevchenko, Vasilij G.; Tedesco, Edward F. (September 2006), "Asteroid albedos deduced from stellar occultations", Icarus 184 (1): 211–220, doi:10.1016/j.icarus.2006.04.006, Bibcode: 2006Icar..184..211S.
External links
- 757 Portlandia at AstDyS-2, Asteroids—Dynamic Site
- 757 Portlandia at the JPL Small-Body Database
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