Minor Planets

Non-linear secular resonances of g-type, i.e. involving the frequency of precession g of the asteroid pericentre, can affect the proper eccentricities of asteroids in resonant or near-resonant configurations. We first identified objects that could potentially be affected by non-linear secular resonances of this type. We then numerically integrated these objects and checked for their resonant argument. We identified a population of 1517 asteroids in g − 2g 6 + g 5 librating states, and of 128 objects in g − 3g 6 + 2g 5 resonant configurations. While secular resonances are rather extended structures and many objects from different and unrelated parts of the main belt could be encountered within, we found that g − 2g 6 + g 5 librators are predominantly of the S taxonomical type (56 per cent of the total), but with a significant fraction of other spectral types. No spectral type dominates in the population of g − 3g 6 + 2g 5 resonators. Several asteroid families are affected by the g − 2g 6 + g 5 secular resonance. The Astraea group is cut into two by this resonance, while the Tirela and Brasilia groups are on the resonance centre and on the left side, respectively. The g − 2g 6 + g 5 secular can significantly affect the shape of families inside the resonance, such as Astraea. It can also increase the flux of asteroids to nearby powerful mean-motion resonances, such as the 5J:-2A and the 2J:-1A. As expected, the long-term effect of g-type resonances on inclinations is essentially negligible. According to Williams (1969), secular resonances play an important role in the dynamics of small bodies in the Solar system. They can change the eccentricity and inclination of objects that were captured in librating states of these resonances, and sculpt the shape of asteroid families in their neighbourhood. Linear secular resonances occur when there is a commensurability between the precession frequency of the longitude of pericentre g, or of the longitude of the node s of a given asteroid and the frequencies of a planet. The three main linear secular resonances in the Solar system are ν 6 = g − g 6 , ν 5 = g − g 5 and ν 16 = s − s 6 (Kneževic et al. 1991; Morbidelli & Henrard 1991), where g 5 = 4.257, g 6 = 28.243, and s 6 = −26.345 arcsec yr −1. Non-linear secular resonances involve higher order combination of frequencies, as for the case of the z k = k(g − g 6) + s − s 6 = kν 6 + ν 16 (k = 1, 2, 3.. .) secular resonances. Amongst non-linear secular resonances, g-type secular resonances are those that only involve the g asteroidal frequency (and other planetary frequencies), as for example, the cases of the 2ν 6 − ν 5 = g − 2g 6 + g 5 or 3ν 6 − 2ν 5 = g − 3g 6 + 2g 5 secular resonances. The main focus of this work will be to study the dynamical evolution of asteroids interacting with g-type secular resonances, so as to ascertain the number of objects currently in librating states, (VC) the dynamical importance of each given resonance, especially when non-gravitational forces such as the Yarkovsky and YORP effects are accounted for, and their effect on selected asteroid families. 2 R E S O NA N C E DY NA M I C S F O R N O N-L I N E A R S E C U L A R R E S O NA N C E S As a preliminary criterion to identify asteroids inside the g-type non-linear secular resonances, we used Carruba (2009) approach. Given the z 1 secular resonance of argument z 1 = g − g 6 + s − s 6 , we considered as objects most likely to be in librating states those for which g + s = (g 6 + s 6) ± 0.3 arcsec yr −1. Since the width of the librating region for asteroids in the fourth-order secular resonance tends to be less than 0.3 arcsec yr −1 (Carruba 2009), we believe that this could be a good criterion to identify objects likely to be in fourth-and sixth-order g-type non-linear secular resonances. For the purpose of identifying objects in the regions affected by g-type non-linear secular resonances, we used a catalogue of 406 251 synthetic proper elements numerically computed with numbered and multiposition asteroids available at the AstDyS data base (Kneževi´c & Milani 2003) 1. According to the theory, the asteroid 1

This paper gives a detailed overview of biotic assemblages recovered from the Deccan trap intercalated sedimentary sequences (infra-and intertrappean beds) of peninsular India as a result of extensive research done during the last 20 years. The infra-and intertrappean beds contain remnants of Gondwanan forms such as myobatrachinae frogs, pelomedusid turtles, dinosaurs (i.e. titanosaurids and abelisaurids), and mammals. Apart from these Gondwanan elements, the infra-and intertrappean beds also contain forms of Laurasian affinity though recently doubt has been cast on such relationships. Based on previous fossil records, Laurasiatic forms were considered to be represented by a great variety of micro-and megavertebrate assemblages such as discoglossid and pelobatid frogs, anguid lizards, alligatorid crocodiles, palaeoryctid mammals, charophytes and ostracodes. The biotic assemblages show a remarkable similarity between the infra-and intertrappean beds indicating a short time period for the deposition of these Deccan volcano-sedimentary beds. The recovered biotic assemblages strongly indicate a Maastrichtian age for the initiation of Deccan volcanic activity and the sedimentary beds associated with it. The Cretaceous/Tertiary boundary as such remains to be defined in any known sections in sedimentary sequences in so far investigated localities of peninsular India. What have been identified are Maastrichtian age beds in the east-central and western Narmada river region on the basis of pollens, vertebrate assemblage and planktonic foraminiferas in infratrappean offshore sequences. A Palaeocene intertrappean bed at Lalitpur (Uttar Pradesh) that is among those lacking dinosaurian remains but having palynological assemblages similar to those from well established Palaeocene sequences, suggests the presence of Palaeocene intertrappeans, but the K/T boundary is yet to be properly defined. q

A decade has yielded much progress in understanding polar disturbance and community recovery-mainly through quantifying ice scour rates, other disturbance levels, larval abundance and diversity, colonization rates and response of benthos to predicted climate change. The continental shelf around Antarctica is clearly subject to massive disturbance, but remarkably across so many scales. In summer, millions of icebergs from sizes smaller than cars to larger than countries ground out and gouge the sea floor and crush the benthic communities there, while the highest wind speeds create the highest waves to pound the coast. In winter, the calm associated with the sea surface freezing creates the clearest marine water in the world. But in winter, an ice foot encases coastal life and anchor ice rips benthos from the sea floor. Over tens and hundreds of thousands of years, glaciations have done the same on continental scales-ice sheets have bulldozed the seabed and the zoobenthos to edge of shelves. We detail and rank modern disturbance levels (from most to least): ice; asteroid impacts; sediment instability; wind/wave action; pollution; UV irradiation; volcanism; trawling; non-indigenous species; freshwater inundation; and temperature stress. Benthic organisms have had to recolonize local scourings and continental shelves repeatedly, yet a decade of studies have demonstrated that they have (compared with lower latitudes) slow tempos of reproduction, colonization and growth. Despite massive disturbance levels and slow recolonization potential, the Antarctic shelf has a much richer fauna than would be expected for its area. Now, West Antarctica is among the fastest warming regions and its organisms face new rapid changes. In the next century, temperature stress and non-indigenous species will drastically rise to become dominant disturbances to the Antarctic life. Here, we describe the potential for benthic organisms to respond to disturbance, focusing particularly on what we know now that we did not a decade ago.

In 2007, the asteroid Kalliope will reach one of its annual equinoxes. As a consequence, its small satellite Linus orbiting in the equatorial plane will undergo a season of mutual eclipses and occultations very similar to the one that the Galilean satellites undergo every 6 years. This paper is aimed at preparing a campaign of observations of these mutual events occurring from February to May 2007. This opportunity occurs only under favorable geometric conditions when the Sun and/or the Earth are close to the orbital plane of the system. This is the first international campaign devoted to the observation of photometric events within an asynchronous asteroidal binary system. We took advantage of a reliable orbit solution of Linus to predict a series of 24 mutual eclipses and 12 mutual occultations observable in the spring of 2007. Thanks to the brightness of Kalliope (m v ' 11), these observations are easy to perform even with a small telescope. Anomalous attenuation events could be observed lasting for about 1-3 h with amplitude up to 0.09 mag. The attenuations are of two distinct types that can clearly be identified as primary and secondary eclipses similar to those that have been previously observed in other minor planet binary systems . Photometric survey of binary near-Earth asteroids. Icarus 181, 63-93]. With these favorable circumstances, such photometric observations will provide us tight constraints regarding physical properties of Linus such as the size, shape and synodic spin period. r

The Rafita asteroid family is an S-type group located in the middle main belt, on the right-hand side of the 3J:-1A mean-motion resonance. The proximity of this resonance to the family left-hand side in the semimajor axis caused many former family members to be lost. As a consequence, the family shape in the (a, 1/D) domain is quite asymmetrical, with a preponderance of objects on the right-hand side of the distribution. The Rafita family is also characterized by a leptokurtic distribution in inclination, which allows the use of methods of family age estimation recently introduced for other leptokurtic families such as Astrid, Hansa, Gallia and Barcelona. In this work, we propose a new method based on the behaviour of an asymmetry coefficient function of the distribution in the (a, 1/D) plane to date incomplete asteroid families such as Rafita. By monitoring the time behaviour of this coefficient for asteroids simulating the initial conditions at the time of the family formation, we were able to estimate that the Rafita family should have an age of 490 ± 200 Myr, in good agreement with results from independent methods such as Monte Carlo simulations of Yarkovsky and YORP dynamical induced evolution and the time behaviour of the kurtosis of the sin (i) distribution. Asteroids from the Rafita family can reach orbits similar to 8 per cent of the currently known near-Earth objects. During the final 10 Myr of the simulation, 1 per cent of the simulated objects are present in NEO space, and thus would be comparable to objects in the present-day NEO population.

Context. The EUROpean Near Earth Asteroid Research (EURONEAR) is a network which envisions to bring some European contributions into the general context traced by the Spaceguard Foundation which was carried out during the last 15 years mainly by the US with some modest European and amateur contributions. Aims. The number of known Near Earth Asteroids (NEAs) and Potentially Hazardous Asteroids (PHAs) has increased tremendously, mainly thanks to five major surveys all focused on the discovery of new bodies. But also other facilities are required to follow-up and improvement the orbital parameters and to study the physical properties of the known bodies. These goals are better achieved by a co-ordinated network such as EURONEAR.