CCD photometry of 23 minor planets

Ortiz

et al. 2014

A&A

It is well known that some Main Belt asteroids show comet-like features. A representative example is the first known Main Belt comet 133P/(7968) Elst-Pizarro. If the mechanisms causing this activity are too weak to develop visually evident comae or tails, the objects stay unnoticed. We are presenting a novel way to search for active asteroids, based on looking for objects with deviations from their expected brightnesses in a database. Just by using the MPCAT-OBS Observation Archive we have found five new candidate objects that possibly show a type of comet-like activity, and the already known Main Belt comet 133P/(7968) Elst-Pizarro. Four of the new candidates, (315) Constantia, (1026) Ingrid, (3646) Aduatiques, and (24 684) 1990 EU4, show brightness deviations independent of the object's heliocentric distance, while (35 101) 1991 PL16 shows deviations dependent on its heliocentric distance, which could be an indication of a thermal triggered mechanism. The method could be implemented in future sky survey programmes to detect outbursts on Main Belt objects almost simultaneously with their occurrence.

Section: (1026) Ingridsupporting

confidence: 79%

A photometric search for active Main Belt asteroids

Ortiz

et al. 2014

A&A

“…Figure 1 shows obtained J-band light curve of (1270) Datura. The sidereal rotation period was derived to be 3.359 hr and the amplitude was about 0.4 mag pv , which are consistent with previous results (Székely et al 2005).…”

Section: Observations and Resultssupporting

confidence: 91%

Rotation-Resolved Spectroscopy of a Very Young Asteroid, (1270) Datura

Takato

2008

ApJ

(1270) Datura is the largest member of a very young asteroid cluster that was thought to be broken-up 0.45 Myr ago. The light-curve and the rotation-resolved reflectance spectra (0.6 um - 1.0 um) were observed in order to find "fresh" surface. Our data show no significant spectral variation along the rotation phase. The depth of the 0.95 um absorption band, which indicates the degree of space weathering, was similar to that of an old S-type asteroid. This suggests that the reflectance spectrum in this wavelength range changes rapidly and saturates the depth of the 0.95 um absorption in less than 0.45 Myr in the main belt environment.Comment: 8 pages, 3 figures, accepted for publication in the ApJ Lette

“…It was observed by Wisniewski et al (1997) during the 1990/1991 opposition, and Székely et al (2005) during the 2000 opposition. Analyses of both datasets indicated relatively short rotation period of ∼3.2−3.4 h, but they were limited enough to allow linkage across the 10 yr interval of time between them.…”

Section: Observationsmentioning

confidence: 96%

“…Our new observations were combined with the older data of Wisniewski et al (1997) and Székely et al (2005), and analysed using the lightcurve inversion method of Kaasalainen and collaborators (e.g., Kaasalainen et al 2001Kaasalainen et al , 2003. This procedure provides a simultaneous solution of the fundamental rotation parameters, rotation period P, and pole position (λ, β), in addition to parameters describing the irregular shape of the asteroid.…”

Section: Spin State and Shape Of (1270) Daturamentioning

confidence: 99%

Datura family: the 2009 update

Vokrouhlický¹,

Ďurech²,

Michałowski

et al. 2009

A&A

Context. Research of asteroid families has been recently refreshed by the discovery of very young ones. These families are of great interest because they represent the product of their parent body fragmentation before orbital and physical evolutionary processes can change them. A cluster of seven objects around the largest body (1270) Datura is of particular interest because it has enough known members and resides in the inner part of the main asteroid belt, facilitating observations. Aims. We carried out photometric observations of the two largest members of the Datura family -asteroids (1270) Datura and (90265) 2003 CL5 -with the goal of inferring their physical parameters. We also used numerous astrometric observations of Datura-family members in the past few years to revisit the age of this cluster. Methods. We performed numerous photometric observations of (1270) Datura over several oppositions. We then used the lightcurve inversion method to determine the spin state and shape of this asteroid. In the case of (90265) 2003 CL5, for which only limited lightcurve data have been acquired so far, we used Fourier analysis to determine the synodic rotation period during the 2008 apparition. We also used backward numerical integration of the improved orbits of Datura family members to reduce uncertainty in its age. Results. We determined the rotation state of (1270) Datura, the largest member of its own family. Its major properties are a short rotation period of ∼3.36 h and small obliquity, which, however, exhibits ∼±15 • excursions because of a forced Cassini state of the proper nodal frequency. Any possible initial non-principal rotation state has probably been damped and the asteroid rotates about the shortest axis of the inertia tensor. Its global shape, although convex in our representation, may reflect regions related to the excavation of the family members from the parent body surface. Interestingly, the second largest member of the Datura family -(90265) 2003 CL5 -appears to be very slow rotator with the rotation period ∼24 h. The large amplitude of its rotation curve suggests that its shape is extremely elongated, possibly bi-lobed. Improved orbits of the family members allow us to re-determine the possible age of this family. We find an age that is slightly older than previously reported. Using a conservative approach, we obtain an age in the 450 to 600 kyr range. With strengthened, but plausible, conditions, we find that the current data may support an age of 530±20 kyr. Further astrometric and photometric observations of the Datura cluster members are needed to determine its age more accurately.