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1627 Ivar

Elongated stony asteroid and near-Earth object

Field	Value
minorplanet	yes
name	1627 Ivar
background	#FFC2E0
image	1627Ivar (Lightcurve Inversion).png
caption	Light-curve-based 3D-model of Ivar
discovery_ref
discovered	25 September 1929
discoverer	E. Hertzsprung
discovery_site	Johannesburg Obs.
(Leiden Southern Station)
mpc_name	(1627) Ivar
alt_names	1929 SH1957 NA
1957 XA
named_after	Ivar Hertzsprung
(discoverer's brother)
mp_category	NEOAmor
orbit_ref
epoch	4 September 2017 (JD 2458000.5)
uncertainty	0
observation_arc	87.62 yr (32,002 days)
aphelion	2.6015 AU
perihelion	1.1240 AU
time_periastron	2023-Sep-09
semimajor	1.8628 AU
eccentricity	0.3966
period	2.54 yr (929 days)
mean_anomaly	229.02°
mean_motion	/ day
inclination	8.4513°
asc_node	133.14°
arg_peri	167.76°
moid	0.1117 AU43.5 LD
dimensions	≈15×6×6 km
km
9.12 km
km
km
rotation	h
h
h

h<ref name	"Hanus-2015a" /

h<ref name	"Skiff-2012a" /
h
h
h
h
h
albedo
0.15
0.151 (taken)
spectral_type	S (Tholen)S (SMASS)
SrwS
B–V = 0.872
U–B = 0.459
abs_magnitude	12.8712.9013.0013.1713.213.24

(Leiden Southern Station) 1957 XA (discoverer's brother) km 9.12 km km km h h

h h h h h h

0.15 0.151 (taken) SrwS B–V = 0.872 U–B = 0.459

1627 Ivar (provisional designation ****) is an elongated stony asteroid and near-Earth object of the Amor group, approximately 15×6×6 km. It was discovered on 25 September 1929, by Danish astronomer Ejnar Hertzsprung at Leiden Southern Station, annex to the Johannesburg Observatory in South Africa. It was named after Ivar Hertzsprung, brother of the discoverer. 1627 Ivar was the first asteroid to be imaged by radar, in July 1985 by the Arecibo Observatory.

Classification and orbit

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 an eccentricity of 0.40 and an inclination of 8° with respect to the ecliptic. Ivar's observation arc begins with its official discovery observation in 1929, as no precoveries were taken, and no prior identifications were made.

It has an Earth minimum orbit intersection distance of 0.1117 AU which corresponds to 43.5 lunar distances. The eccentric Amor asteroid is also a Mars-crosser. In August 2074, it will pass Earth at 0.141 AU, closer than it actually approached Mars in July 1975 (0.150 AU).

Physical characteristics

In the SMASS and Tholen taxonomic scheme, Ivar is characterized as a common stony S-type asteroid.

Rotation period

A large number of rotational lightcurves of Ivar have been obtained from photometric observations since 1985 (see infobox). They give a well-defined rotation period between 4.795 and 4.80 hours with a brightness variation between 0.27 and 1.40 magnitude, indicative of its non-spheroidal shape (also see 3D-model image). New radar and visual observations refined the period to 4.7951689 ± 0.0000026 hours. Future photometric observations will show whether the YORP effect will slowly change the body's spin rate (as seen with 1862 Apollo).

In 1985, the body was observed with radar from the Arecibo Observatory in Puerto Rico at a distance of 0.20 AU. The measured radar cross-section was 7.5 square kilometers. It was the first asteroid to be imaged by radar. Radar observations have been performed again in June & July 2013 and July 2018.

Diameter and albedo

According to the EXPLORENEOs survey carried out by the Spitzer Space Telescope, thermal infrared observations by the Keck Observatory, and NASA's Wide-field Infrared Survey Explorer with its subsequent NEOWISE mission, and thermal modeling by Alan Harris, Ivar measures between 8.37 and 10.2 kilometers in diameter, and it surface has an albedo between 0.09 and 0.15. The Collaborative Asteroid Lightcurve Link adopts an albedo of 0.151 and a diameter of 9.12 kilometers with an absolute magnitude of 12.87. 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%.

Naming

This minor planet was named by the discoverer in honor of his late brother Ivar Hertzsprung. The official was published by the Minor Planet Center in February 1959 (M.P.C. 1860).

References

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|display-authors = 6

References

(July 2017). "Radar and Lightcurve Shape Model of Near-Earth Asteroid (1627) Ivar". Icarus.
[https://history.nasa.gov/SP-4218/ch9.htm To See the Unseen, A History of Planetary Radar Astronomy - chapter 9], Andrew J. Butrica, The NASA History Series
(July 2012). "Lowell Observatory Near-Earth Asteroid Photometric Survey (NEAPS) - 2008 May through 2008 December". Minor Planet Bulletin.
(February 2001). "CCD photometric investigations of small bodies in the solar system". link. Publications of the Astronomy Department of the Eötvös University

Info: Wikipedia Source

This article was imported from Wikipedia and is available under the Creative Commons Attribution-ShareAlike 4.0 License. Content has been adapted to SurfDoc format. Original contributors can be found on the article history page.

amor-asteroids discoveries-by-ejnar-hertzsprung named-minor-planets radar-imaged-asteroids s-type-asteroids-(smass) s-type-asteroids-(tholen) astronomical-objects-discovered-in-1929

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