Evidence for layered methane clouds in Titan’s troposphere

Layered methane clouds in Titan’s troposphere with an upper methane ice cloud, a lower liquid methane-nitrogen cloud, and a gap in between were suggested from in situ measurements and ground-based observations. Here we report laboratory investigations under conditions that mimic Titan’s troposphere providing a detailed picture of the cloud layers. A solid methane cloud with a nitrogen content of less than 14% and a liquid methane-nitrogen cloud with a nitrogen content of ∼30% form above ∼19 km and below ∼16 km altitude, respectively. Contrary to previous assertions, long-lived supercooled liquid methane-nitrogen droplets can be sustained in the region in between. The results demonstrate that a cloud gap could only form in the presence of high amounts of other traces species (ethane nuclei, tholin particles, etc.).     

Cosmological magnetic fields: their generation,evolution and observation

We review the possible mechanisms for the generation of cosmological magnetic fields, discuss their evolution in an expanding Universe filled with the cosmic plasma and provide a critical review of the literature on the subject. We put special emphasis on the prospects for observational tests of the proposed cosmological magnetogenesis scenarios using radio and gamma-ray astronomy and ultra-high-energy cosmic rays. We argue that primordial magnetic fields are observationally testable. They lead to magnetic fields in the intergalactic medium with magnetic field strength and correlation length in a well defined range.We also state the unsolved questions in this fascinating open problem of cosmology and propose future observations to address them.     

Land use,associated eel production,and abundance of fish and crayfish in streams in Waikato,New Zealand

Abstract

The density and biomass of fish and crayfish, and the production of eels, was compared among streams in native forest, exotic forest, and pasture. Populations were estimated by multiple‐pass electroshocking at 11 sites in hill‐country streams in the Waikato region, North Island. Three sites were in native forest, four in exotic forest, and four in pasture. Length of stream sampled at each site was 46–94 m (41–246 m² in area), and catchment areas up stream of the sites ranged from 0.44 to 2.01 km².

A total of 487 fish were caught. The species were longfinned and shortfinned eels, banded kokopu, Cran's and redfinned bullies, and common smelt. Eels were the most abundant fish in all three land‐use types, and shortfinned eels were more abundant at pastoral sites (mean density 1.11 fish m^?2) than longfinned eels (mean density 0.129 fish m^?2). Banded kokopu were present only at forested sites. Mean fish densities were greater at pastoral sites (1.55 fish m^?2) than under either native forest (0.130 fish m^?2) or exotic forest (0.229 fish m^?2). Mean fish biomass was also greater at pastoral sites (89.7 g m^?2) than under native forest (12.8 g m^?2) or exotic forest (19.3 g m^?2). Longfinned eels made a greater contribution to the fish biomass at all sites than did shortfinned eels. Densities of crayfish were high (0.46–5.40 crayfish m^?2), but were not significantly different between land‐use types. Crayfish biomass ranged from 1.79 to 11.2 g m^?2. Total eel production was greater at pastoral sites (mean 17.9 g m^?2 year¹) than at forest sites (mean 2.39 gm^?2 year^?1).     

Distribution,abundance and growth of New Zealand sea lion Phocarctos hookeri pups on Campbell Island

Nine weeks field work was completed during two trips in January/February and March/ April 2003 to investigate the distribution and abundance of New Zealand sea lion Phocarctos hookeri pups at Campbell Island. A total of 161 pups were tagged and a further 138 dead pups were found. A closed mark‐recapture model was used to estimate the total number of live pups (e.g., tagged plus untagged pups) at Campbell Island in April as 247 (SE = 28, 95% CI 198–308). Pup production at Campbell Island is estimated at 385, which comprises 13% of the total pup production for the species in the 2003 season. This is the first robust estimate of pup production for New Zealand sea lions at Campbell Island. The figure of 385 pups is considerably higher than any of the previous estimates reported from Campbell Island. The high level of pup mortality (36%) at Campbell Island for approximately the first 2 months after birth is higher than the 17% reported for the Auckland Islands for approximately the same period in 2003, but is similar to unusually high levels of mortality (20–30%) reported at the Auckland Islands in recent years. It was not possible to determine the cause of death of the 138 dead pups owing to scavenging and decomposition. Pups were found over the whole Island, with the exception of its northern end. Male pups were significantly heavier and faster growing than female pups over the same period.     

Periodicities in the high-mass X-ray binary system RX J0146.9+6121/LS I+61°235

The high-mass X-ray binary RX J0146.9+6121, with optical counterpart LS I+61°235 (V831 Cas), is an intriguing system on the outskirts of the open cluster NGC 663. It contains the slowest Be type X-ray pulsar known with a pulse period of around 1400 s and, primarily from the study of variation in the emission line profile of Hα, it is known to have a Be decretion disc with a one-armed density wave period of approximately 1240 d. Here we present the results of an extensive photometric campaign, supplemented with optical spectroscopy, aimed at measuring short time-scale periodicities. We find three significant periodicities in the photometric data at, in order of statistical significance, 0.34, 0.67 and 0.10 d. We give arguments to support the interpretation that the 0.34 and 0.10 d periods could be due to stellar oscillations of the B-type primary star and that the 0.67 d period is the spin period of the Be star with a spin axis inclination of  23⁺¹⁰₋₈  degrees. We measured a systemic velocity of  −37.0 ± 4.3 km s⁻¹  confirming that LS I+61°235 has a high probability of membership in the young cluster NGC 663 from which the system's age can be estimated as 20–25 Myr. From archival RXTE All Sky Monitor (ASM) data we further find 'super' X-ray outbursts roughly every 450 d. If these super outbursts are caused by the alignment of the compact star with the one-armed decretion disc enhancement, then the orbital period is approximately 330 d.     

Solar circumstances at the time of the cosmic ray increase on January 28, 1967

Solar circumstances have been evaluated for January 28, 1967, the date of an observed ground level enhancement of cosmic rays which was not preceded by observation of a suitably great Hα flare. On the visible solar hemisphere, a bright subflare at S23° E19° occurred in appropriate time association with the cosmic ray event, and was accompanied by weak X-ray enhancement and radio frequency emission. If this flare, alone, or in combination with other minor flares observed on the visible hemisphere on January 28 was the source of the energetic cosmic rays recorded on that date, then current thinking regarding the characteristics of cosmic ray flares must be modified. An initial study of probable circumstances on the invisible hemisphere did not lead to the immediate recognition of amajor center of activity as the probable source of a cosmic ray flare. Further evaluation of all centers of activity on the invisible hemisphere identified one region, McMath Plage No. 8687, 64° beyond the west limb, as the most plausible, possible site for the cosmic ray flare on January 28, 1967. The location of this region is in accord with the source-position deduced in Lockwood's analysis (1968) of the cosmic ray event. This center of activity could not have been more than 5 days old on January 28, 1967. The interval of major activity in the region was confined primarily to the invisible hemisphere. The occurrence of an ‘isolated’ major flare in the region on February 13, 1967 is discussed. The present study exemplifies the partial nature of solar observations which are limited to the visible hemisphere. The possible role of exceptional geomagnetic calm, 1963–1967, in permitting atypical cosmic ray enhancements, as on January 28, 1967, is mentioned.     

The proton flare of August 28, 1966

The proton flare of August 28, 1966 began on H records at 15^h21^m35^s UT. It presented an unusually complex development with flare emission occurring in two distinct plages. The brightest part of the flare attained maximum intensity, 152 % of the continuum, between 15^h30^m and 15^h32^m UT. Photometric measurements show that a long-enduring part of the flare continued to decline in intensity until at least 21^h20^m UT.The flare developed first in parts of the plages that were near the extremities of a filament and a complex system of curvilinear absorption structures, possibly an eruptive prominence in projection. During the rise to maximum intensity a large expanding feature moved southward from the site of the flare with a velocity 700 km/sec. Its appearance on monochromatic records of the chromosphere made in the center of H and 0.5 Å on either side was consistent with the effect of an advancing phenomenon that induces a small shift of the H absorption line, first to longer, and then to shorter wavelengths.Two bright flare-filaments were obvious aspects of the event by 15^h28^m and dominated the main phase of the flare. Loop-type prominences were observed in absorption as early as 15^h40^m.This investigation was supported in part by the Office of Naval Research through funds from Nonr-1224(19), and in part by the National Science Foundation through funds from GA-632.     

Preterrestrial aqueous alteration of the Lafayette (SNC) meteorite

Abstract— The Lafayette meteorite, a nakhlite of the SNC (Martian?) group, contains hydrous alteration materials as intergranular films and as veinlets and patches replacing olivine, pyroxenes, and high-Si glass. The alteration materials (“iddingsite”) consist of ferroan smectite clays, magnetite (or maghemite), and ferrihydrite, as shown by SEM and TEM. Three varieties of veinlets are present and formed in the order: coarse phyllosilicate; fine-grained (phyllosilicate-oxide), and porous oxide. Veinlets of fine-grained material cross-cut coarse phyllosilicate veinlets. The alteration materials are preterrestrial, as they are older than Lafayette's fusion crust, which is glassy and not affected by any alterations. Approaching the crust, the veinlets are progressively modified to the point of melting, and progressively depleted in adsorbed volatile constituents (S, Cl, and P). Bulk compositions of the alteration veinlets (SEM and TEM EDX) are consistent with the observed mineralogy, and suggest: that the smectite contains significant adsorbed S and Cl; that the ferrihydrite contains significant adsorbed S, but not Cl; that rare grains of sulfate (Ca?) and chloride (Na or K?) are present; and that the compositions of the alteration materials are approximated by Lafayette's olivine + high-Si glass + water. We estimate that Lafayette's alteration materials formed at less than 100 °C. The oxidation potential of the water was near or slightly below that of the magnetite-hematite buffer. The presence of sulfate and chloride in discrete phases and as adsorbates on ferrihydrite and smectite suggests that the altering solutions were saline. However, relatively little mass was transferred into or out of Lafayette because the bulk composition of the alteration materials is nearly isochemical with a mixture of magmatic silicate phases and water. Chemical transport within Lafayette was also limited, as alteration materials preserve some chemical signature of their host minerals. Presence of alteration materials along only some grain boundaries and some cracks suggests that Lafayette was not soaked in fluid. These last two inferences suggest that the alteration of Lafayette took place during episodic infiltrations of small volumes of saline water.     

Compositional variations of olivines and pyroxenes in chondritic interplanetary dust particles

Abstract We report here analyses of olivines and pyroxenes, and petrofabrics of 27 chondritic interplanetary dust particles (IDPs), comparing those from anhydrous and hydrous types. Approximately 40% of the hydrous particles contain diopside, a probable indicator of parent body thermal metamorphism, while this mineral is rarely present in the anhydrous particles. Based on this evidence, we find that hydrous and anhydrous IDPs are, in general, not directly related, and we conclude that olivine and pyroxene major-element compositions can be used to help discriminate between IDPs that are (1) predominantly nebular condensates, and lately resided in anhydrous or icy (no liquids) primitive parent bodies, and (2) those originating from more geochemically active parent bodies (probably hydrous and anhydrous asteroids).