77 Frigga

77 Frigga is a large, M-type, possibly metallic main-belt asteroid. It was discovered by the German-American astronomer C. H. F. Peters on November 12, 1862. The object is named after Frigg, the Norse goddess. The asteroid is orbiting the Sun with a period of 4.36 years and completes a rotation on its axis every nine hours.

77 Frigga

Discovery
Discovered by	Christian Heinrich Friedrich Peters
Discovery date	November 12, 1862
Designations
MPC designation	(77) Frigga
Pronunciation	/ˈfrɪɡə/[1]
Named after	Frigg
Minor planet category	Main belt
Adjectives	[citation needed]
Orbital characteristics
Epoch December 31, 2006 (JD 2454100.5)
Aphelion	452.196 Gm (3.023 AU)
Perihelion	346.228 Gm (2.314 AU)
Semi-major axis	399.212 Gm (2.669 AU)
Eccentricity	0.133
Orbital period (sidereal)	1592.266 d (4.36 a)
Average orbital speed	18.15 km/s
Mean anomaly	346.682°
Inclination	2.433°
Longitude of ascending node	1.332°
Argument of perihelion	61.419°
Physical characteristics
Dimensions	60.0 × 74.0 km[2]
Mean diameter	61.390 ± 0.177 km[3]
Mass	(4.16 ± 2.30/1)×1017 kg[4]
Mean density	3.434 ± 1.901/0.827 g/cm3[4]
Equatorial surface gravity	0.0074 m/s²
Equatorial escape velocity	0.0301 km/s
Synodic rotation period	9.0032 hr[3]
Geometric albedo	0.177 ± 0.025[3] 0.144[5]
Spectral type	M
Absolute magnitude (H)	8.65[3]

Frigga has been studied by radar.^[6] The spectra of this asteroid displays a feature at a wavelength of 3 μm, indicating the presence of hydrated minerals on the surface.^[7] The near infrared spectrum is reddish and shows no spectral absorption features. Potential analogs of this spectrum include enstatite chondrites and nickel-iron meteorites.^[8]

A three-chord occultation plot of the asteroid 77 Frigga, observed 2018 April 11th from eastern Australia.

Since 1999 there have been four stellar occultations by the asteroid. The first three were single chord observations, and the fourth was a 3-chord observation, and a miss. The best fit ellipse measures 60.0 × 74.0 kilometres at PA -14degrees.^[2]

References

1. Upton, Clive; Kretzschmar, William A. Jr. (2017). The Routledge Dictionary of Pronunciation for Current English (2nd ed.). Routledge. p. 519. ISBN 978-1-138-12566-7.
2. "PDS Asteroid/Dust Subnode". sbn.psi.edu. Archived from the original on 25 April 2018. Retrieved 19 May 2018.
3. "JPL Small-Body Database Browser: 77 Frigga" (2012-01-04 last obs). Jet Propulsion Laboratory. Retrieved 27 January 2012.
4. Fienga, A.; Avdellidou, C.; Hanuš, J. (February 2020). "Asteroid masses obtained with INPOP planetary ephemerides". Monthly Notices of the Royal Astronomical Society. 492 (1). doi:10.1093/mnras/stz3407.
5. Asteroid Data Sets Archived 2009-12-17 at the Wayback Machine
6. "Radar-Detected Asteroids and Comets". NASA/JPL Asteroid Radar Research. Retrieved 27 January 2012.
7. Gil-Hutton, R. (March 2007), "Polarimetry of M-type asteroids", Astronomy and Astrophysics, 464 (3): 1127−1132, Bibcode:2007A&A...464.1127G, doi:10.1051/0004-6361:20066348.
8. Takir, D.; et al. (March 2008), "The Near-Infrared Spectroscopy of Two M-Class Main Belt Asteroids, 77 Frigga and 325 Heidelberga", 39th Lunar and Planetary Science Conference, (Lunar and Planetary Science XXXIX), held March 10-14, 2008 in League City, Texas. LPI Contribution No. 1391., p. 1084, Bibcode:2008LPI....39.1084T

External links

• Lightcurve plot of 77 Frigga, Palmer Divide Observatory, B. D. Warner (2012)
• Asteroid Lightcurve Database (LCDB), query form (info Archived 16 December 2017 at the Wayback Machine)
• Dictionary of Minor Planet Names, Google books
• Asteroids and comets rotation curves, CdR – Observatoire de Genève, Raoul Behrend
• Discovery Circumstances: Numbered Minor Planets (1)-(5000) – Minor Planet Center
• 77 Frigga at AstDyS-2, Asteroids—Dynamic Site
  • Ephemeris · Observation prediction · Orbital info · Proper elements · Observational info
• 77 Frigga at the JPL Small-Body Database
  • Close approach · Discovery · Ephemeris · Orbit viewer · Orbit parameters · Physical parameters