Asteroid (101955) Bennu’s weak boulders and thermally anomalous equator

Thermal inertia and surface roughness are proxies for the physical characteristics of planetary surfaces. Global maps of these two properties distinguish the boulder population on near-Earth asteroid (NEA) (101955) Bennu into two types that differ in strength, and both have lower thermal inertia than expected for boulders and meteorites. Neither has strongly temperature-dependent thermal properties. The weaker boulder type probably would not survive atmospheric entry and thus may not be represented in the meteorite collection. The maps also show a high–thermal inertia band at Bennu’s equator, which might be explained by processes such as compaction or strength sorting during mass movement, but these explanations are not wholly consistent with other data. Our findings imply that other C-complex NEAs likely have boulders similar to those on Bennu rather than finer-particulate regoliths. A tentative correlation between albedo and thermal inertia of C-complex NEAs may be due to relative abundances of boulder types.

Fusulines from the Central Asturian Coal? eld (Pennsylvanian, Cantabrian Zone, Spain) and their signi? cance for biostratigraphic correlation

The Central Asturian Coalfield of the Cantabrian Zone (NW Spain) exposes a Moscovian (Middle Pennsylvanian) succession, up to 5000-m thick, which records stratigraphically signi? cant terrestrial and marine fossils such as fossil ? ora and fusulines. The present paper focuses on the fusuline-bearing limestones of this succession, which cover a time span ranging from latest Bashkirian to early Myachkovian. 36 fusuline species are described and illustrated, among them the new species Schubertella luisorum Villa. This study reveals that the composition of the Kashirian to early Myachkovian fusuline assemblages is similar to that of the Beedeina-dominated assemblages of the Donets Basin, which were interpreted by Khodjanyazova et al. (2014) as occurring during early high-stands. In parallel with this, the absence of species representing the Fusulinella-dominated assemblages of the later authors is observed, while their Hemifusulina-dominated assemblages are replaced in the Central Asturian Coalfield by monospecific associations of Hemifusulina. Biostratigraphic data inferred from these microfaunas allowed us to assign an age to several informal stratigraphic intervals known as ‘mining stratal packages’ and to propose a tentative correlation with some relevant horizons of the Donets Basin.

Climatic Conditions in the Western and Northern Cordillera During the Last Glaciation: Paleoecological Evidence

ABSTRACTIn the southern Cordillera, paleoecological evidence suggests that climate was variable, from cooler than present by up to 3°C, to possibly similar to modern during the Olympia non-glacial interval (> 59 TO 25-29 ka). The development of open subalpine parkland vegetation in lowlands after 25 ka reflects slow cooling to glacial conditions. Assumptions about continuously cold and dry glacial conditions are tested and disputed. Between 18-19 ka, pollen, plant macrofossil and beetle evidence suggest relatively warm and moist conditions in the Fraser/Puget Lowlands. A tentative correlation can be inferred with the recently defined "Hanging Lake thermal event" around 18-22 ka in the unglaciated Yukon. Further work should be done to test this inference. Paleobotanical data suggest that increasing moisture, rather than increased cooling, was responsible for the late Vashon ice advance in the southwestern Cordillera. The controversy regarding the nature of the vegetation cover in eastern Beringia, north of the main Cordilleran ice sheet, is not yet settled, although evidence to date favours a complex mosaic of tundra and "steppe-tundra" plant communities supporting a greater diversity of grazing large mammals than exist in the area today.

The On/Off nature of star-planet interactions in the HD 179949 and υ And systems

Evidence suggesting an observable magnetic interaction between a star and its hot Jupiter (Porb< 7 days,a< 0.1 AU,Mpsini> 0.2MJ) appears as a cyclic variation of stellar activity synchronized to the planet's orbit. HD 179949 has been observed almost every year since 2001. Synchronicity of the Ca II H & K emission with the orbit is clearly seen in four out of six epochs, while rotational modulation withProt=7 days is apparent in the other two seasons. We observe a similar phenomenon on υ And, which displays rotational modulation (Prot=12 days) in September 2005, while in 2002 and 2003 variations appear to correlate with the planet's orbital period. This on/off nature of star-planet interaction (SPI) in the two systems is likely a function of the changing stellar magnetic field structure throughout its activity cycle. The tentative correlation between this activity in the 13 stars we have observed to date and the ratio ofMpsinito the planet's rotation period, a quantity proportional to the hot Jupiter's magnetic moment, first presented in Shkolniket al. (2005) remains viable. This work furthers the characterization of SPI, improving its potential as a probe of extrasolar planetary magnetic fields.