HEBE
MINOR PLANET 6 HEBE
NOTE THAT HEBE IS SOMEWHAT FAINTER THAN VESTA (WHICH IS TOO NEAR THE SUN TO SEE) BUT IS WELL PLACED TO OBSERVE NOT THAT FAR FROM NAKED- EYE VARIABLE STAR MIRA (AKA OMICRON CETI)
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Coarse finder chart
(60° field-of-view, stars to mag. 6.5)
Fine finder chart
(2° field-of-view, stars to mag. 12)
NOTE JUPITER AND URANUS WILL BE SEPARATING TIL NOVEMBER BUT THEN WILL CONVERGE FOR ANOTHER CLOSE CONJUNCTION ON 2011 JANUARY 2nd.
DATA ABOVE IS FROM HEAVENS-ABOVE.COM
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FROM WIKIPEDIA:
6 Hebe (pronounced /ˈhiːbiː/ HEE-bee, or as in Greek: ‘Ήβη) is a large main-belt asteroid, containing around half a percent of the mass of the belt. Its apparently high bulk density (greater than that of the Earth's Moon or even Mars), however, means that by volume it does not rank among the top twenty asteroids. This high bulk density suggests an extremely solid body that has not been impacted by collisions, which is not typical of asteroids of its size – they tend to be loosely bound rubble piles.
In brightness, Hebe is the fifth brightest object in the asteroid belt behind Vesta, Ceres, Iris and Pallas. It has a mean opposition magnitude of +8.3, about equal to the mean brightness of Titan[6] and can reach +7.5 at an opposition near perihelion.
Hebe is probably the parent body of the H chondrite meteorites, which account for a remarkable 40% of all meteorites striking the Earth.
6 Hebe
Discovery
Designations
Physical Characteristics
Discovery
Size comparison: the first 10 asteroids profiled against Earth's Moon. Hebe is fifth from the right.
Hebe was the sixth asteroid to be discovered, on July 1, 1847 by Karl Ludwig Hencke. It was the second and final asteroid discovery by Hencke, who had previously found 5 Astraea. The name "Hebe" was proposed by Carl Friedrich Gauss.
Major Meteorite Source
6 Hebe is the probable parent body of the H chondrite meteorites and the IIE iron meteorites.
The Orbit of 6 Hebe Compared with the orbits of Earth, Mars and Jupiter
Remarkably, this would imply that it is the source of about 40% of all meteorites striking the Earth. Evidence for this connection includes the following (after Michael Gaffey and Sarah L. Gilbert.[7]):
The spectrum of Hebe matches a mix of 60% H chondrite and 40% IIE iron meteorite material.
The IIE type are unusual among the iron meteorites, and probably formed from impact melt, rather than being fragments of the core of a differentiated asteroid.
The IIE irons and H chondrites likely come from the same parent body, due to similar trace mineral and oxygen isotope ratios.
Asteroids with spectra similar to the ordinary chondrite meteorites (accounting for 85% of all falls, including the H chondrites) are extremely rare.
6 Hebe is extremely well placed to send impact debris to Earth-crossing orbits. Ejecta with even relatively small velocities (~280 m/s) can enter the chaotic regions of the 3:1 Kirkwood gap at 2.50 AU and the nearby
secular resonance which determines the high-inclination edge of the main belt at about 16° inclinations hereabouts.
Of the asteroids in this "well-placed" orbit, Hebe is the largest.
An analysis of likely contributors to the Earth's meteorite flux places 6 Hebe at the top of the list,[8] due to its position and relatively large size. If Hebe is not the H-chondrite parent body, then where are the meteorites from Hebe?[7]
Physical Characteristics
Lightcurve analysis suggests that Hebe has a rather angular shape, which may be due to several large impact craters.[3] Hebe rotates in a prograde direction, with the north pole pointing towards ecliptic coordinates (β, λ) = (45°, 339°) with a 10° uncertainty.[3] This gives an axial tilt of 42°.
It has a bright surface and, if its identification as the parent body of the H chondrites is correct, a surface composition of silicate chondritic rocks mixed with pieces of nickel-iron metal. A likely scenario for the formation of the surface metal is as follows:
Large impacts caused local melting of the iron rich H chondrite surface. The metals, being heavier, would have settled to the bottom of the magma lake, forming a metallic layer buried by a relatively shallow layer of silicates.
Later sizeable impacts broke up and mixed these layers.
Small frequent impacts tend to preferentially pulverize the weaker rocky debris, leading to an increased concentration of the larger metal fragments at the surface, such that they eventually comprise ~40% of the immediate surface at the present time.
Moon
On March 5, 1977 Hebe occulted Kaffaljidhma (γ Ceti), a moderately bright 3rd magnitude star. No other observed occultations by Hebe have been reported.
As a result of that occultation, a small Hebean moon was reported by Paul D. Maley.[9] It was nicknamed "Jebe" (see Heebie Jeebies). However, the discovery has not been confirmed.
References
Yeomans, Donald K.. "Horizons system". NASA JPL. http://ssd.jpl.nasa.gov/?horizons. Retrieved 2007-03-20. — Horizons can be used to obtain a current ephemeris
^ a b c Jim Baer (2008). "Recent Asteroid Mass Determinations". Personal Website. http://home.earthlink.net/~jimbaer1/astmass.txt. Retrieved 2008-11-28.
^ a b c J. Torppa et al. Shapes and rotational properties of thirty asteroids from photometric data, Icarus, Vol. 164, p. 346 (2003).
^ Planetary Data System Small Bodies Node, lightcurve parameters
^ Donald H. Menzel and Jay M. Pasachoff (1983). A Field Guide to the Stars and Planets (2nd edition ed.). Boston, MA: Houghton Mifflin. pp. 391. ISBN 0395348358.
^ a b M. J. Gaffey & S. L. Gilbert Asteroid 6 Hebe: The probable parent body of the H-Type ordinary chondrites and the IIE iron meteorites, Meteoritics & Planetary Science, Vol. 33, p. 1281 (1998).
^ A. Morbidelli et al. Delivery of meteorites through the ν6 secular resonance, Astronomy & Astrophysics, Vol. 282, p. 955 (1994).
External Links
shape model deduced from lightcurve
MNRAS 7 (1847) 283 (discovery announcement)
Retrieved from "http://en.wikipedia.org/wiki/6_Hebe"
Categories: Main Belt asteroids | Asteroids named from Greek mythology | S-type asteroids | Astronomical objects discovered in 1847
THE STAR CHART BELOW IS DESIGNED FOR THE SOUTHERN HEMISPHERE
SO IT IS UPSIDE DOWN FOR NORTHERN HEMISPHERE OBSERVERS --
THAT MEANS SOUTH IS POINTED UP
Royal Astronomical Society of New Zealand
(6) Hebe
Chart showing path of Hebe and Flora in the second part of 2010 Positions of Hebe for 2010
Hebe at Opposition in 2010
Hebe will be in Aquarius as it brightens in June, but quite quickly moves across a corner of Pisces and then into Cetus at the beginning of August. In Cetus its main movement is to the south so that the asteroid becomes higher in southern skies. It is stationary on August 25 and reaches opposition on September 19. Its magnitude will then be 7.7 making it briefly the brightest asteroid in the sky. At this time it will be about 4° from the second magnitude star β Cet.
Hebe reaches its second stationary point at the end of October after which it recommences moving to the east. By then it will also have started moving back to the north. During the next two months it will fade from binocular view, reaching magnitude 9.5 by the end of the year.
The asteroid (8) Flora will be fairly close to Hebe for some of this time. It will follow a somewhat similar path to to Hebe in Aquarius, but will be rather fainter.
The diameter of Hebe is about 200 km. Its orbital period is 3.78 years, its distance from the Sun varies between 1.93 and 2.92 AU, so that at the most favourable oppositions the asteroid will be about 0.93 AU from the Earth. The orbit is inclined at 14.8° to the ecliptic.
Hebe was discovered in 1847 on July 1 by K L Hencke at Driesen.
Chart showing paths of Hebe and Flora during the second part of 2010.
The chart is a southern hemisphere view with north at the bottom and east to the right. Stars to magnitude 9.0 are shown, which is about the limiting magnitude of 50 mm aperture binoculars. The circle on the chart represents a field of view 5° in diameter, a fairly typical field of view for binoculars.
Chart prepared using GUIDE 8.0. Program produced by Project Pluto.
Positional data for Hebe during 2010.
Top of Page Other Asteroids for 2010 RASNZ home page
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