12923 Zephyr (prov. designation :1999 GK4 ) is a stony asteroid , classified as potentially hazardous asteroid and near-Earth object of the Apollo group , approximately 2 kilometers (1.2 miles) in diameter. It was discovered on 11 April 1999, by astronomers of the Lowell Observatory Near-Earth Object Search at Anderson Mesa Station near Flagstaff, Arizona.[ 4] Zephyrus from Greek mythology.[ 3]
Orbit and classification
Zephyr orbits the Sun at a distance of 1.0–2.9 AU once every 2 years and 9 months (1,003 days). Its orbit has an eccentricity of 0.49 and an inclination of 5° with respect to the ecliptic .[ 1] observation arc begins with a precovery taken at Palomar Observatory in April 1955, almost 44 years prior to its official discovery observation at Anderson Mesa.[ 4]
Close encounters
This near-Earth asteroid has an Earth minimum orbital intersection distance of 0.0211 AU (3,160,000 km), which corresponds to 8.2 lunar distances .[ 1] potentially hazardous asteroid . In September 2010, the asteroid approached Earth at 0.2546 AU (38,100,000 km); it will make close encounters with Earth again in 2021, 2032 and 2043.[ 1]
Naming
This minor planet was named after the god of the west wind, Zephyrus , from Greek mythology . The name was suggested by M. Smitherman.[ 3] Minor Planet Center on 28 September 2004 (M.P.C. 52768[ 13]
Physical characteristics
In the SMASS classification , Zephyr is a common S-type asteroid .[ 1] Infrared Telescope Facility ,[ 10] Tholen classification (noisy spectrum).[ 11]
Rotation period
In April 1999, a rotational lightcurve of Zephyr was obtained from photometric observations by Czech astronomer Petr Pravec at Ondřejov Observatory . Lightcurve analysis gave a well-defined rotation period of 3.891 hours with a brightness amplitude of 0.18 magnitude (U=3 [ a]
Diameter and albedo
According to the survey carried out by the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer and the ExploreNEOs survey of the Spitzer Space Telescope , Zephyr measures between 1.86 and 2.062 kilometers in diameter and its surface has an albedo between 0.1764 and 0.21.[ 5] [ 6] [ 7] [ 8] [ 9]
The Collaborative Asteroid Lightcurve Link adopts Petr Pravec's revised WISE data, with albedo of 0.1764 and a diameter of 2.06 kilometers based on an absolute magnitude of 15.93.[ 11]
Notes
References
^ a b c d e f g h i j "JPL Small-Body Database Browser: 12923 Zephyr (1999 GK4)" (2017-01-19 last obs.). Jet Propulsion Laboratory . Retrieved 17 October 2017 .^ "zephyr" Oxford English Dictionary Oxford University Press .(Subscription or participating institution membership required.) ^ a b c Schmadel, Lutz D. (2006). "(12923) Zephyr [1.96, 0.49, 5.3]". Dictionary of Minor Planet Names – (12923) Zephyr, Addendum to Fifth Edition: 2003–2005 . Springer Berlin Heidelberg . p. 76. doi :10.1007/978-3-540-34361-5_734 . ISBN 978-3-540-34361-5 ^ a b c d "12923 Zephyr (1999 GK4)" . Minor Planet Center . Retrieved 17 October 2017 .^ a b c Harris, A. W.; Mommert, M.; Hora, J. L.; Mueller, M.; Trilling, D. E.; Bhattacharya, B.; et al. (March 2011). "ExploreNEOs. II. The Accuracy of the Warm Spitzer Near-Earth Object Survey" (PDF) . The Astronomical Journal . 141 (3): 10. Bibcode :2011AJ....141...75H . doi :10.1088/0004-6256/141/3/75 . ^ a b c Mainzer, A.; Grav, T.; Bauer, J.; Masiero, J.; McMillan, R. S.; Cutri, R. M.; et al. (December 2011). "NEOWISE Observations of Near-Earth Objects: Preliminary Results". The Astrophysical Journal . 743 (2): 17. arXiv :1109.6400 Bibcode :2011ApJ...743..156M . doi :10.1088/0004-637X/743/2/156 . ^ a b c d Mainzer, A.; Grav, T.; Masiero, J.; Hand, E.; Bauer, J.; Tholen, D.; et al. (November 2011). "NEOWISE Studies of Spectrophotometrically Classified Asteroids: Preliminary Results". The Astrophysical Journal . 741 (2): 25. arXiv :1109.6407 Bibcode :2011ApJ...741...90M . doi :10.1088/0004-637X/741/2/90 . ^ a b c d 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 . ^ a b Thomas, C. A.; Trilling, D. E.; Emery, J. P.; Mueller, M.; Hora, J. L.; Benner, L. A. M.; et al. (September 2011). "ExploreNEOs. V. Average Albedo by Taxonomic Complex in the Near-Earth Asteroid Population" . The Astronomical Journal . 142 (3): 12. Bibcode :2011AJ....142...85T . doi :10.1088/0004-6256/142/3/85 ^ a b Thomas, Cristina A.; Emery, Joshua P.; Trilling, David E.; Delbó, Marco; Hora, Joseph L.; Mueller, Michael (January 2014). "Physical characterization of Warm Spitzer-observed near-Earth objects". Icarus . 228 : 217–246. arXiv :1310.2000 Bibcode :2014Icar..228..217T . doi :10.1016/j.icarus.2013.10.004 . ^ a b c d "LCDB Data for (12923) Zephyr" . Asteroid Lightcurve Database (LCDB). Retrieved 17 October 2017 .^ Veres, Peter; Jedicke, Robert; Fitzsimmons, Alan; Denneau, Larry; Granvik, Mikael; Bolin, Bryce; et al. (November 2015). "Absolute magnitudes and slope parameters for 250,000 asteroids observed by Pan-STARRS PS1 – Preliminary results". Icarus . 261 : 34–47. arXiv :1506.00762 Bibcode :2015Icar..261...34V . doi :10.1016/j.icarus.2015.08.007 . ^ "MPC/MPO/MPS Archive" . Minor Planet Center . Retrieved 17 October 2017 .
External links
