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7505 Furusho
Discovery
Discovered by	T. Kobayashi
Discovery site	Ōizumi Obs.
Discovery date	3 January 1997
Designations
MPC designation	(7505) Furusho
Named after	Reiko Furusho ; (Japanese astronomer)
Alternative designations	1997 AM2 · 1940 WC; 1944 OG · 1950 BA1; 1970 WG · 1991 NS
Minor planet category	Mars-crosser
Orbital characteristics
	Epoch 27 April 2019 (JD 2458600.5)
	Uncertainty parameter 0
Observation arc	77.37 yr (28,258 d)
Aphelion	3.6410 AU
Perihelion	1.6305 AU
Semi-major axis	2.6357 AU
Eccentricity	0.3814
Orbital period (sidereal)	4.28 yr (1,563 d)
Mean anomaly	132.46°
Mean motion	0° 13m 49.08s / day
Inclination	6.3771°
Longitude of ascending node	86.492°
Argument of perihelion	288.02°
Earth MOID	0.645 AU (251 LD)
Mars MOID	0.2486 AU
Physical characteristics
Mean diameter	9.07±0.7 km; 10.04±1.00 km
Synodic rotation period	4.139±0.001 h
Geometric albedo	0.211; 0.3732
Spectral type	S (assumed)
Absolute magnitude (H)	11.9; 12.30

7505 Furusho, provisional designation 1997 AM₂, is a stony asteroid and sizable Mars-crosser on an eccentric orbit from the asteroid belt, approximately 10 kilometers (6.2 miles) in diameter. It was discovered on 3 January 1997, by Japanese astronomer Takao Kobayashi at the Ōizumi Observatory in the Kantō region of Japan.^[1] The assumed S-type asteroid is likely elongated in shape and has a rotation period of 4.1 hours. It was named for Japanese astronomer Reiko Furusho.^[1]

Orbit and classification

Furusho is a member of the Mars-crossing asteroids, a dynamically unstable group between the main belt and the near-Earth populations, crossing the orbit of Mars at 1.66 AU.^[1] It orbits the Sun at a distance of 1.6–3.6 AU once every 4 years and 3 months (1,563 days; semi-major axis of 2.64 AU). Its orbit has a high eccentricity of 0.38 and an inclination of 6° with respect to the ecliptic.^[2] The body's observation arc begins with its first observation as 1940 WC at the Crimean Simeiz Observatory in November 1940, or more than 56 years prior to its official discovery observation by Takao Kobayashi at Ōizumi in January 1997.^[1]

Naming

This minor planet was named after Japanese astronomer Reiko Furusho (born 1970). Her research includes cometary physics, in particular the measurement of polarized light, caused by scattering on comet dust. Furusho also works in the education and popularization of astronomy.^[1] The official naming citation was published by the Minor Planet Center on 1 May 2003 (M.P.C. 48388).^[7]

Physical characteristics

Furusho is an assumed S-type asteroid.^[3]

Rotation period

In November 2017, a rotational lightcurve of Furusho was obtained from photometric observations by Daniel Klinglesmith at Etscorn Observatory (719) in Socorro, New Mexico. Lightcurve analysis gave a well-defined rotation period of 4.139±0.001 hours with a high brightness variation of 0.63 magnitude (U=3).^[6]

The result agrees with previous period determinations by Hungarian astronomers at Konkoly Observatory in autumn 2001 (U=3),^[8] and with observations by astronomers at the Palomar Transient Factory in California in May 2011 (U=3).^[9] Robert Stephens at Santana Observatory (646) and Brian Warner at the Palmer Divide Station (U82) also determined an identical period in November 2001 and December 2013, respectively (U=3/3).^[10]^[11] All observations showed a classically shaped bimodal lightcurve with a high brightness amplitude between 0.52 and 0.75 magnitude, which is indicative of an elongated, non-spherical shape.^[a]

Diameter and albedo

According to the survey carried out by the Infrared Astronomical Satellite IRAS, Furusho measures 9.07 kilometers in diameter and its surface has an albedo of 0.37.^[4] In 2017, a study dedicated to Mars-crossing asteroids by the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer determined a diameter of 10.04 kilometers with an albedo of 0.21.^[5] The Collaborative Asteroid Lightcurve Link derives an albedo of 0.29 and a diameter of 8.9 kilometers based on an absolute magnitude of 12.20.^[3]

Sizable Mars-crosser

With a diameter of 10 kilometers, Furusho is a typical "sizable" Mars-crosser (5–15 km) of which two dozens or so are known. These include 3581 Alvarez (13.7 km) 1065 Amundsenia (9.8 km), 1139 Atami (9.4 km), 3737 Beckman (14.4 km), 1474 Beira (15.5 km), 5682 Beresford (7.3 km), 7369 Gavrilin (5.5 km), 1011 Laodamia (7.4 km), 6170 Levasseur (5.7 km), 1727 Mette (5.4 km), 1131 Porzia (7.1 km), 985 Rosina (8.2 km), 1235 Schorria (5.6 km), 1310 Villigera (15.2 km), and 1468 Zomba (7 km), which are themselves smaller than the largest members of this dynamical group, namely, 132 Aethra, 323 Brucia (former Mars-crosser), 1508 Kemi, 2204 Lyyli and 512 Taurinensis, all larger than 20 kilometers.

Notes

^ ^a ^b Lightcurve plot of (7505) Furusho, by Brian Warner rotation period 4.140±0.005 hours with a brightness amplitude of 0.52±0.02 mag. Quality code is 3. Summary figures at the LCDB.

References

^ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ "7505 Furusho (1997 AM2)". Minor Planet Center. Retrieved 14 November 2018.
^ ^a ^b ^c ^d "JPL Small-Body Database Browser: 7505 Furusho (1997 AM2)" (2018-04-12 last obs.). Jet Propulsion Laboratory. Retrieved 14 November 2018.
^ ^a ^b ^c ^d "LCDB Data for (7505) Furusho". Asteroid Lightcurve Database (LCDB). Retrieved 14 November 2018.
^ ^a ^b ^c ^d Tedesco, E. F.; Noah, P. V.; Noah, M.; Price, S. D. (October 2004). "IRAS Minor Planet Survey V6.0". NASA Planetary Data System – IRAS-A-FPA-3-RDR-IMPS-V6.0: IRAS-A-FPA-3-RDR-IMPS-V6.0. Bibcode:2004PDSS...12.....T. Retrieved 14 November 2018.
^ ^a ^b ^c ^d Alí-Lagoa, V.; Delbo', M. (July 2017). "Sizes and albedos of Mars-crossing asteroids from WISE/NEOWISE data". Astronomy and Astrophysics. 603: 8. arXiv:1705.10263. Bibcode:2017A&A...603A..55A. doi:10.1051/0004-6361/201629917.
^ ^a ^b Klinglesmith, Daniel A. III; Hendrickx, Sebastian (April 2018). "Asteroid Lightcurve Observations at Etscorn Observatory". The Minor Planet Bulletin. 45 (2): 162–165. Bibcode:2018MPBu...45..162K. ISSN 1052-8091.
^ "MPC/MPO/MPS Archive". Minor Planet Center. Retrieved 14 November 2018.
^ Székely, P.; Kiss, L. L.; Szabó, Gy. M.; Sárneczky, K.; Csák, B.; Váradi, M.; et al. (August 2005). "CCD photometry of 23 minor planets". Planetary and Space Science. 53 (9): 925–936. arXiv:astro-ph/0504462. Bibcode:2005P&SS...53..925S. doi:10.1016/j.pss.2005.04.006.
^ 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): 35. arXiv:1504.04041. Bibcode:2015AJ....150...75W. doi:10.1088/0004-6256/150/3/75.
^ Stephens, R. D. (June 2001). "Rotational Periods and Lightcurves of 1277 Dolores, 666 Desdemona and (7505) 1997 AM2". The Minor Planet Bulletin. 28: 28–29. Bibcode:2001MPBu...28...28S.
^ Warner, Brian D. (April 2014). "Asteroid Lightcurve Analysis at CS3-Palmer Divide Station: 2013 September-December". The Minor Planet Bulletin. 41 (2): 102–112. Bibcode:2014MPBu...41..102W. ISSN 1052-8091.