44 Nysa is a large and very bright main-belt

asteroid An asteroid is a minor planet of the inner Solar System. Sizes and shapes of asteroids vary significantly, ranging from 1-meter rocks to a dwarf planet almost 1000 km in diameter; they are rocky, metallic or icy bodies with no atmosphere. ...

, and the brightest member of the Nysian asteroid family. It is classified as a rare class E asteroid and is probably the largest of this type (though

55 Pandora Pandora (minor planet designation: 55 Pandora) is a fairly large and very bright asteroid in the asteroid belt. Pandora was discovered by American astronomer and Catholic priest George Mary Searle on September 10, 1858, from the Dudley Observato ...

is only slightly smaller).

Discovery

It was discovered by Hermann Goldschmidt on May 27, 1857, and named after the mythical land of

Nysa Nysa may refer to: Greek Mythology * Nysa (mythology) or Nyseion, the mountainous region or mount (various traditional locations), where nymphs raised the young god Dionysus * Nysiads, nymphs of Mount Nysa who cared for and taught the infant ...

Greek mythology A major branch of classical mythology, Greek mythology is the body of myths originally told by the Ancient Greece, ancient Greeks, and a genre of Ancient Greek folklore. These stories concern the Cosmogony, origin and Cosmology#Metaphysical co ...

Physical properties

In 2002 Kaasalainen ''et al.'' used 63 lightcurves from the Uppsala Asteroid Photometric Catalog (UAPC) to construct a shape model of 44 Nysa. The shape model is conical, which they interpreted as indicating the asteroid may actually be a contact

binary Binary may refer to: Science and technology Mathematics * Binary number, a representation of numbers using only two digits (0 and 1) * Binary function, a function that takes two arguments * Binary operation, a mathematical operation that t ...

. In 2003, Tanga ''et al.'' published results obtained from the Fine Guidance Sensor on the

Hubble Space Telescope The Hubble Space Telescope (often referred to as HST or Hubble) is a space telescope that was launched into low Earth orbit in 1990 and remains in operation. It was not the first space telescope, but it is one of the largest and most versa ...

in which high-precision interferometry was performed on Nysa with the goal of a more accurate shape determination. Due to Hubble's orbit around the Earth, hours-long photometry sessions, as are normally used to resolve the asteroid's shape, were not possible. Instead, the team used interferometry on the asteroid at the time in its rotation when it would have its longest axis perpendicular to the Earth. Ellipsoidal shape models were then fit to the resulting data to determine an estimate of the asteroid's shape. Both single and double ellipsoid models were fit to the data with both providing approximately the same goodness of fit; leaving the team unable to differentiate between a single elongated object and the contact binary model put forth by Kaasalainen ''et al.'' An observation of an occultation by 44 Nysa of TYC 6273-01033-1 from the Dutch amateur astronomer Harrie Rutten showed a two-phase reappearance on March 20, 2012. This confirms the conical shape or the binary nature of Nysa. In December 2006, Shepard ''et al.'' performed three days of

radar Radar is a detection system that uses radio waves to determine the distance (''ranging''), angle, and radial velocity of objects relative to the site. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, w ...

observations on Nysa with the

Arecibo radio telescope The Arecibo Telescope was a spherical reflector radio telescope built into a natural sinkhole at the Arecibo Observatory located near Arecibo, Puerto Rico. A cable-mount steerable receiver and several radar transmitters for emitting signals wer ...

. The asteroid was found to have a high radar

polarization Polarization or polarisation may refer to: Mathematics *Polarization of an Abelian variety, in the mathematics of complex manifolds *Polarization of an algebraic form, a technique for expressing a homogeneous polynomial in a simpler fashion by ...

value (''μ_c'') of 0.50 ± 0.2, a radar albedo (

\hat_

) of 0.19 ± 0.06, and a visual albedo (''p_v'') of 0.44 ± 0.10. The albedo measurements were based on a shape model worked out at Arecibo. The best fit shape model as measured by the Arecibo team has parameters a/b = 1.7 ± 0.1, a/c = 1.6–1.9, with an a-axis of 113 ± 10 km; this gives an effective diameter of 79 ± 10 km, which is in agreement with the HST study by Tanga ''et al.'' in 2003. The data gathered also showed signs of significant concavity in Nysa's structure, but the dip in the radar curves is not pronounced enough to indicate bifurcation, calling into question whether or not Nysa really is a contact binary. Nysa has so far been reported

occulting An occultation is an event that occurs when one object is hidden from the observer by another object that passes between them. The term is often used in astronomy, but can also refer to any situation in which an object in the foreground blocks ...

star A star is an astronomical object comprising a luminous spheroid of plasma (physics), plasma held together by its gravity. The List of nearest stars and brown dwarfs, nearest star to Earth is the Sun. Many other stars are visible to the naked ...

three times.

Studies

44 Nysa was in a study of asteroids using the Hubble FGS. Asteroids studied include

63 Ausonia Ausonia ( minor planet designation: 63 Ausonia) is a stony Vestian asteroid from the inner region of the asteroid belt, approximately 100 kilometers (60 miles) in diameter. It was discovered by Italian astronomer Annibale de Gasparis on 10 Febru ...

15 Eunomia Eunomia (minor planet designation 15 Eunomia) is a very large asteroid in the inner asteroid belt. It is the largest of the stony ( S-type) asteroids, with 3 Juno as a close second. It is quite a massive asteroid, in 6th to 8th place (to withi ...

43 Ariadne Ariadne (minor planet designation: 43 Ariadne) is a fairly large and bright main-belt asteroid. It is the second-largest member of the Flora asteroid family. It was discovered by N. R. Pogson on 15 April 1857 and named after the Greek heroine Ar ...

, 44 Nysa, and 624 Hektor.

Notes

References

External links

* * {{DEFAULTSORT:000044 Nysa asteroids

E-type asteroids (Tholen) Xc-type asteroids (SMASS) 18570527 vec:Lista de asteroidi#44 Nisa