49P/Arend–Rigaux

49P/Arend–Rigaux is a periodic comet with a 6.75-year orbit around the Sun. It is the first of three comets discovered by Belgian astronomer Sylvain Arend and the only one for Fernand Rigaux.

Observational history

Discovery

While on a routine search for new asteroids in the sky, Sylvain Arend and Fernand Rigaux discovered a new comet on the night of 5 February 1951.Template:Sfn It was a diffuse 11th-magnitude object within the constellation Canis Minor.Template:Efn

Physical characteristics

Nucleus size

The first physical measurements of its nucleus in 1985 revealed that it has a geometric albedo of 0.028, placing it as one of the darkest objects in the Solar System,Template:R which is even compared to D-type asteroids and C/1983 H1.Template:R These initial measurements suggest that the nucleus is elongated and has an effective radius between Template:Cvt.Template:R Photometry of direct thermal emission taken in the same year suggested a nuclear radius of Template:Cvt.Template:R In 2004, a definitive radii measurement based on previous studies found that the nucleus is Template:Cvt across.Template:R

Rotation

Initial CCD photometry taken during its 1984/1985 apparition revealed a cyclic variation in the comet's brightness indicating a rotation period between Template:Val to Template:Val hours.Template:R This is later revised to 13.47 hours following the reanalysis of narrow-band photometry in visible and near-ultraviolet spectrum.Template:R Follow-up observations during its 2012 apparition found it has a double-peaked lightcurve change, which revealed it has a retrograde synodic rotation period lasting 13.452 hours instead.Template:R

Other features

Analysis of infrared observations from Spitzer obtained in 2006 combined with ground observations in 2012 revealed a broad tail-like feature and a narrow jet emitting subsurface volatiles,Template:R specifically amorphous water ice, that have recently been exposed by comet's multiple passes from the Sun.Template:R

Orbit

Template:As of, comet Arend–Rigaux orbits the Sun at distances between Template:Convert and Template:Convert, inclined about 19 degrees from the ecliptic.Template:R

The first orbital calculations for Arend–Rigaux were taken by Joseph L. Brady and Nevin Sherman on 19 February 1951.Template:RTemplate:Sfn Leland E. Cunningham noted that the comet's preliminary orbit somewhat resembles that of 69P/Taylor, which was a lost comet at the time.Template:R In 1954, Vitaly A. Bronshten hypothesized that Arend–Rigaux is one of two fragments of comet Taylor, with the second one returning as D/1952 B1 (Harrington–Wilson) a year later after 49P.Template:R However, the connection between the two comets were later disproven, and comet Taylor itself would not be rediscovered until 1977.Template:R

On 20 December 2058 the comet will pass Template:Convert from Mars.Template:R

External links

• Template:JPL Small Body
• 49P/Arend–Rigaux at Seiichi Yoshida's website
• 49P/Arend–Rigaux at Gary W. Kronk's Cometography