Ivar orbits the Sun at a distance of 1.1–2.6 AU once every 2 years and 6 months (929 days). Its orbit has aneccentricity of 0.40 and aninclination of 8° with respect to theecliptic.[1] Ivar'sobservation arc begins with its official discovery observation in 1929, as noprecoveries were taken, and no prior identifications were made.[3]
It has an Earthminimum orbit intersection distance of 0.1117 AU (16,700,000 km) which corresponds to 43.5lunar distances. The eccentric Amor asteroid is also aMars-crosser. In August 2074, it will pass Earth at 0.141 AU, closer than it actually approached Mars in July 1975 (0.150 AU).[1]
A large number of rotationallightcurves of Ivar have been obtained from photometric observations since 1985(see infobox). They give a well-definedrotation period between 4.795 and 4.80 hours with a brightness variation between 0.27 and 1.40magnitude, indicative of its non-spheroidal shape(also see 3D-model image).[15][16][27] New radar and visual observations refined the period to 4.7951689 ± 0.0000026 hours.[4] Future photometric observations will show whether theYORP effect will slowly change the body's spin rate (as seen with1862 Apollo).[10]
In 1985, the body was observed with radar from theArecibo Observatory in Puerto Rico at a distance of 0.20 AU. The measuredradar cross-section was 7.5 square kilometers.[28] It was the first asteroid to beimaged by radar.[26] Radar observations have been performed again in June & July 2013 and July 2018.
According to the EXPLORENEOs survey carried out by theSpitzer Space Telescope, thermal infrared observations by theKeck Observatory, and NASA'sWide-field Infrared Survey Explorer with its subsequentNEOWISE mission, and thermal modeling by Alan Harris, Ivar measures between 8.37 and 10.2 kilometers in diameter, and it surface has analbedo between 0.09 and 0.15.[5][6][7][8] TheCollaborative Asteroid Lightcurve Link adopts an albedo of 0.151 and a diameter of 9.12 kilometers with anabsolute magnitude of 12.87.[22] According to model based on radar and photometric observations Ivar is an elongated asteroid with maximum extensions along the three body-fixed coordinates being 15.15 × 6.25 × 5.66 km ± 10%.[4]
^abcdCrowell, Jenna L.;Howell, Ellen S.; Magri, Christopher; Nolan, Michael C.; Fernández, Yanga R.; Richardson, James E.; Warner, Brian D.; Marshall, Sean E.; Springmann, Alessondra (July 2017). "Radar and Lightcurve Shape Model of Near-Earth Asteroid (1627) Ivar".Icarus.291:254–267.Bibcode:2017Icar..291..254C.doi:10.1016/j.icarus.2016.11.008.ISSN0019-1035.
^abcdDelbó, Marco; Harris, Alan W.; Binzel, Richard P.; Pravec, Petr; Davies, John K. (November 2003). "Keck observations of near-Earth asteroids in the thermal infrared".Icarus.166 (1):116–130.Bibcode:2003Icar..166..116D.doi:10.1016/j.icarus.2003.07.002.
^Skiff, Brian A.; Bowell, Edward; Koehn, Bruce W.; Sanborn, Jason J.; McLelland, Kyle P.; Warner, Brian D. (July 2012). "Lowell Observatory Near-Earth Asteroid Photometric Survey (NEAPS) – 2008 May through 2008 December".The Minor Planet Bulletin.39 (3):111–130.Bibcode:2012MPBu...39..111S.ISSN1052-8091.
^Harris, A. W.; Young, J. W. (June 1985). "Photometric Results for Earth Approaching Asteroids".Bulletin of the American Astronomical Society.17: 726.Bibcode:1985BAAS...17R.726H.
^abcHahn, G.; Magnusson, P.; Harris, A. W.; Young, J. W.; Belkora, L. A.; Fico, N. J.; et al. (April 1989). "Physical studies of Apollo-Amor asteroids – UBVRI photometry of 1036 Ganymed and 1627 Ivar".Icarus.78 (2):363–381.Bibcode:1989Icar...78..363H.doi:10.1016/0019-1035(89)90184-X.ISSN0019-1035.
^Lupishko, D. F.; Velichko, F. P.; Shevchenko, V. G. (October 1986). "The asteroid 1627 Ivar – UBV photometry, period, and sense of rotation".Kinematika I Fizika Nebesnykh Tel.2:39–43.Bibcode:1986KFNT....2...39L.ISSN0233-7665.
^Skiff, Brian A.; Bowell, Edward; Koehn, Bruce W.; Sanborn, Jason J.; McLelland, Kyle P.; Warner, Brian D. (July 2012). "Lowell Observatory Near-Earth Asteroid Photometric Survey (NEAPS) - 2008 May through 2008 December".Minor Planet Bulletin.39 (3): 111.Bibcode:2012MPBu...39..111S.ISSN1052-8091.
^Ostro, S. J.; Campbell, D. B.; Chandler, J. F.; Shapiro, I. I.; Hine, A. A.; Velez, R.; et al. (October 1991). "Asteroid radar astrometry".Astronomical Journal.102: 1490–1502.ResearchsupportedbyNASA.Bibcode:1991AJ....102.1490O.doi:10.1086/115975.ISSN0004-6256.
.png)
