1657 Roemera

1657 Roemera, provisional designation 1961 EA, is a stony Phocaea asteroid from the inner regions of the asteroid belt, approximately 8 kilometers in diameter. It was discovered on 6 March 1961, by Swiss astronomer Paul Wild at Zimmerwald Observatory near Bern, Switzerland, and later named after American astronomer Elizabeth Roemer.[2][9]

1657 Roemera
Discovery[1]
Discovered byP. Wild
Discovery siteZimmerwald Obs.
Discovery date6 March 1961
Designations
(1657) Roemera
Named after
Elizabeth Roemer
(American astronomer)[2]
1961 EA · 1932 AB
main-belt · (inner)[3]
Phocaea[4]
Orbital characteristics[1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 0
Observation arc84.79 yr (30,971 days)
Aphelion2.9032 AU
Perihelion1.7946 AU
2.3489 AU
Eccentricity0.2360
3.60 yr (1,315 days)
253.33°
Inclination23.372°
105.32°
54.409°
Physical characteristics
Dimensions7.665±0.219 km[5]
8.04 km (calculated)[3]
4.5±1 h[6]
34.0±0.1 h[7]
0.20 (assumed)[3]
0.220±0.030[5]
Tholen = S[1] · S[3]
12.84[1][5] · 12.89±0.16[3][6][8]

    Orbit and classification

    Roemera is a member of the Phocaea family (701),[3][4] a large family of stony asteroids with nearly two thousand known members.[10]: 23  It orbits the Sun in the inner main-belt at a distance of 1.8–2.9 AU once every 3 years and 7 months (1,315 days). Its orbit has an eccentricity of 0.24 and an inclination of 23° with respect to the ecliptic.[1] Roemera was first identified as 1932 AB at Heidelberg Observatory in 1932, extending the body's observation arc by 29 years prior to its official discovery observation at Zimmerwald.[9]

    Physical characteristics

    In the Tholen classification, Roemera is a stony S-type asteroid.[1]

    Lightcurves

    In May 2008, American astronomer Brian Warner obtained a rotational lightcurve of Roemera from photometric observations at his Palmer Divide Observatory in Colorado. It gave a longer than average rotation period of 34.0 hours with a brightness variation of 0.15 magnitude (U=2).[7] Polish astronomer Wiesław Z. Wiśniewski found a different period solution of 4.5 hours with a low amplitude of 0.09 magnitude in March 1990 (U=2).[6]

    Diameter and albedo

    According to the survey carried out by NASA's Wide-field Infrared Survey Explorer with its subsequent NEOWISE mission, Roemera measures 7.66 kilometers in diameter and its surface has an albedo of 0.220,[5] while the Collaborative Asteroid Lightcurve Link assumes a standard albedo for stony asteroids of 0.20 and calculates a diameter of 8.04 kilometers with an absolute magnitude of 12.89.[3]

    Naming

    This minor planet was named by the discoverer in honor American astronomer Elizabeth Roemer (1929–2016), U.S. Naval Observatory, in appreciation of her untiring and successful efforts to advance the knowledge of the motions and physical properties of comets and minor planets.[2] Roemer herself discovered the asteroids 1930 Lucifer and 1983 Bok. The official naming citation was published by the Minor Planet Center on 1 February 1965 (M.P.C. 2347).[11]

    References
    1. "JPL Small-Body Database Browser: 1657 Roemera (1961 EA)" (2016-10-26 last obs.). Jet Propulsion Laboratory. Retrieved 30 June 2017.
    2. Schmadel, Lutz D. (2007). "(1657) Roemera". Dictionary of Minor Planet Names. Springer Berlin Heidelberg. p. 132. doi:10.1007/978-3-540-29925-7_1658. ISBN 978-3-540-00238-3.
    3. "LCDB Data for (1657) Roemera". Asteroid Lightcurve Database (LCDB). Retrieved 24 December 2016.
    4. "Asteroid 1657 Roemera – Nesvorny HCM Asteroid Families V3.0". Small Bodies Data Ferret. Retrieved 26 October 2019.
    5. Masiero, Joseph R.; Mainzer, A. K.; Grav, T.; Bauer, J. M.; Cutri, R. M.; Nugent, C.; et al. (November 2012). "Preliminary Analysis of WISE/NEOWISE 3-Band Cryogenic and Post-cryogenic Observations of Main Belt Asteroids". The Astrophysical Journal Letters. 759 (1): 5. arXiv:1209.5794. Bibcode:2012ApJ...759L...8M. doi:10.1088/2041-8205/759/1/L8. Retrieved 24 December 2016.
    6. Wisniewski, W. Z.; Michalowski, T. M.; Harris, A. W.; McMillan, R. S. (March 1995). "Photoelectric Observations of 125 Asteroids". Abstracts of the Lunar and Planetary Science Conference. 26: 1511. Bibcode:1995LPI....26.1511W. Retrieved 24 December 2016.
    7. Warner, Brian D. (January 2009). "Asteroid Lightcurve Analysis at the Palmer Divide Observatory: 2008 May - September". The Minor Planet Bulletin. 36 (1): 7–13. Bibcode:2009MPBu...36....7W. ISSN 1052-8091. Retrieved 24 December 2016.
    8. Pravec, Petr; Harris, Alan W.; Kusnirák, Peter; Galád, Adrián; Hornoch, Kamil (September 2012). "Absolute magnitudes of asteroids and a revision of asteroid albedo estimates from WISE thermal observations". Icarus. 221 (1): 365–387. Bibcode:2012Icar..221..365P. doi:10.1016/j.icarus.2012.07.026. Retrieved 24 December 2016.
    9. "1657 Roemera (1961 EA)". Minor Planet Center. Retrieved 24 December 2016.
    10. Nesvorný, D.; Broz, M.; Carruba, V. (December 2014). "Identification and Dynamical Properties of Asteroid Families". Asteroids IV. pp. 297–321. arXiv:1502.01628. Bibcode:2015aste.book..297N. doi:10.2458/azu_uapress_9780816532131-ch016. ISBN 9780816532131.
    11. Schmadel, Lutz D. (2009). "Appendix – Publication Dates of the MPCs". Dictionary of Minor Planet Names – Addendum to Fifth Edition (2006–2008). Springer Berlin Heidelberg. p. 221. doi:10.1007/978-3-642-01965-4. ISBN 978-3-642-01964-7.

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