889 Erynia

889 Erynia /ɛˈraɪniə/ is a highly elongated background asteroid from the inner regions of the asteroid belt. It was discovered on 5 March 1918, by German astronomer Max Wolf at the Heidelberg-Königstuhl State Observatory, and given the provisional designations A918 EN and 1918 DG.[1] The stony S-type asteroid (Sl) has a rotation period of 9.89 hours and measures approximately 17 kilometers (11 miles) in diameter. It was named from Greek mythology, after the Erinyes, also known as Furies.[2]

889 Erynia
Modelled shape of Erynia from its lightcurve
Discovery [1]
Discovered byM. F. Wolf
Discovery siteHeidelberg Obs.
Discovery date5 March 1918
Designations
(889) Erynia
Pronunciation/ɛˈraɪniə/
Named after
Erinyes, or Furies
(Greek mythology)[2]
A918 EN · 1929 BG
A912 PA · 1912 PA
1918 DG
main-belt [1][3] · (inner)
background [4][5]
Orbital characteristics [3]
Epoch 31 May 2020 (JD 2459000.5)
Uncertainty parameter 0
Observation arc101.81 yr (37,187 d)
Aphelion2.9428 AU
Perihelion1.9500 AU
2.4464 AU
Eccentricity0.2029
3.83 yr (1,398 d)
342.62°
0° 15m 27.36s / day
Inclination8.1064°
132.53°
278.52°
Physical characteristics
Mean diameter
9.89±0.01 h[8]
  • (187.0°, −60.0°) (λ1/β1)[5][9]
  • (335.0°, −74.0°) (λ2/β2)[5][9]
  • 0.196±0.014[7]
  • 0.230±0.042[6]
11.0[1][3]

    Orbit and classification

    Erynia is a non-family asteroid of the main belt's background population when applying the hierarchical clustering method to its proper orbital elements.[4][5] It orbits the Sun in the inner asteroid belt at a distance of 2.0–2.9 AU once every 3 years and 10 months (1,398 days; semi-major axis of 2.45 AU). Its orbit has an eccentricity of 0.20 and an inclination of 8° with respect to the ecliptic.[3] The asteroid was first observed as A912 PA (1912 PA) at the Johannesburg Observatory on 7 August 1912. The body's observation arc begins at Heidelberg Observatory on 16 March 1918, or elven nights after its official discovery observation.[1]

    Naming

    This minor planet was named after one of the Erinyes from Greek mythology, also known as Furies in Roman mythology. The female deities of vengeance have snakes for hair, dog's heads, coal black bodies, bat's wings, and blood-shot eyes. They tortured their victims with brass-studded scourges and inflicted plagues. The naming was mentioned in The Names of the Minor Planets by Paul Herget in 1955 (H 86).[2]

    Physical characteristics

    In the Tholen-like taxonomy of the Small Solar System Objects Spectroscopic Survey (S3OS2), Erynia is a common stony S-type asteroid, while in the SMASS-like taxonomic variant of the survey, it is an Sl-subtype, which transitions from the S- to the uncommon L-type.[5][10]

    Rotation period and poles
    Lightcurve-based 3D-model of Erynia

    In January 2002, a rotational lightcurve of Erynia was obtained from photometric observations by French astronomer Laurent Bernasconi. Lightcurve analysis gave a rotation period of 9.89±0.01 hours with a high brightness variation of 0.67±0.02 magnitude, indicative of a non-spherical, elongated shape (U=3).[8] A concurring period of 9.872±0.0079 hours and an amplitude 0.47 magnitude was obtained by astronomers at the Palomar Transient Factory in April 2010 (U=2).[11][12] In 2011, a modeled lightcurve using data from the Uppsala Asteroid Photometric Catalogue (UAPC) and other sources gave a sidereal period 9.8749±0.0005 hours, as well as two spin axes at (187.0°, −60.0°) and (335.0°, −74.0°) in ecliptic coordinates (λ, β).[9]

    Diameter and albedo

    According to the survey carried out by the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer (WISE) and the Japanese Akari satellite, Erynia measures (16.682±0.154) and (18.14±0.59) kilometers in diameter and its surface has an albedo of (0.230±0.042) and (0.196±0.014), respectively.[6][7] The Collaborative Asteroid Lightcurve Link assumes a standard albedo for a stony asteroid of 0.20 and calculates a diameter of 18.75 kilometers based on an absolute magnitude of 11.[12]The WISE team also published a mean-diameter of (17.386±0.181 km) with a corresponding albedo of (0.2171±0.0295).[5][12]

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    References
    1. "889 Erynia (A918 EN)". Minor Planet Center. Retrieved 26 February 2020.
    2. Schmadel, Lutz D. (2007). "(889) Erynia". Dictionary of Minor Planet Names. Springer Berlin Heidelberg. p. 80. doi:10.1007/978-3-540-29925-7_890. ISBN 978-3-540-00238-3.
    3. "JPL Small-Body Database Browser: 889 Erynia (A918 EN)" (2019-12-27 last obs.). Jet Propulsion Laboratory. Retrieved 26 February 2020.
    4. "Asteroid 889 Erynia – Proper Elements". AstDyS-2, Asteroids – Dynamic Site. Retrieved 26 February 2020.
    5. "Asteroid 889 Erynia". Small Bodies Data Ferret. Retrieved 26 February 2020.
    6. Masiero, Joseph R.; Grav, T.; Mainzer, A. K.; Nugent, C. R.; Bauer, J. M.; Stevenson, R.; et al. (August 2014). "Main-belt Asteroids with WISE/NEOWISE: Near-infrared Albedos". The Astrophysical Journal. 791 (2): 11. arXiv:1406.6645. Bibcode:2014ApJ...791..121M. doi:10.1088/0004-637X/791/2/121.
    7. Usui, Fumihiko; Kuroda, Daisuke; Müller, Thomas G.; Hasegawa, Sunao; Ishiguro, Masateru; Ootsubo, Takafumi; et al. (October 2011). "Asteroid Catalog Using Akari: AKARI/IRC Mid-Infrared Asteroid Survey". Publications of the Astronomical Society of Japan. 63 (5): 1117–1138. Bibcode:2011PASJ...63.1117U. doi:10.1093/pasj/63.5.1117. Retrieved 24 February 2020. (online, AcuA catalog p. 153)
    8. Behrend, Raoul. "Asteroids and comets rotation curves – (889) Erynia". Geneva Observatory. Retrieved 26 February 2020.
    9. Hanuš, J.; Ďurech, J.; Brož, M.; Warner, B. D.; Pilcher, F.; Stephens, R.; et al. (June 2011). "A study of asteroid pole-latitude distribution based on an extended set of shape models derived by the lightcurve inversion method". Astronomy and Astrophysics. 530: A134. arXiv:1104.4114. Bibcode:2011A&A...530A.134H. doi:10.1051/0004-6361/201116738. ISSN 0004-6361.
    10. Lazzaro, D.; Angeli, C. A.; Carvano, J. M.; Mothé-Diniz, T.; Duffard, R.; Florczak, M. (November 2004). "S3OS2: the visible spectroscopic survey of 820 asteroids" (PDF). Icarus. 172 (1): 179–220. Bibcode:2004Icar..172..179L. doi:10.1016/j.icarus.2004.06.006. Retrieved 26 February 2020.
    11. Waszczak, Adam; Chang, Chan-Kao; Ofek, Eran O.; Laher, Russ; Masci, Frank; Levitan, David; et al. (September 2015). "Asteroid Light Curves from the Palomar Transient Factory Survey: Rotation Periods and Phase Functions from Sparse Photometry". The Astronomical Journal. 150 (3): 75. arXiv:1504.04041. Bibcode:2015AJ....150...75W. doi:10.1088/0004-6256/150/3/75. ISSN 0004-6256.
    12. "LCDB Data for (889) Erynia". Asteroid Lightcurve Database (LCDB). Retrieved 26 February 2020.
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