Comet-like mineralogy of olivine crystals in an extrasolar proto-Kuiper belt.

Some planetary systems harbour debris disks containing planetesimals such as asteroids and comets. Collisions between such bodies produce small dust particles, the spectral features of which reveal their composition and, hence, that of their parent bodies. A measurement of the composition of olivine crystals (Mg(2-2x)Fe(2x)SiO(4)) has been done for the protoplanetary disk HD 100546 (refs 3, 4) and for olivine crystals in the warm inner parts of planetary systems. The latter compares well with the iron-rich olivine in asteroids (x ≈ 0.29). In the cold outskirts of the ß Pictoris system, an analogue to the young Solar System, olivine crystals were detected but their composition remained undetermined, leaving unknown how the composition of the bulk of Solar System cometary olivine grains compares with that of extrasolar comets. Here we report the detection of the 69-micrometre-wavelength band of olivine crystals in the spectrum of ß Pictoris. Because the disk is optically thin, we can associate the crystals with an extrasolar proto-Kuiper belt a distance of 15-45 astronomical units from the star (one astronomical unit is the Sun-Earth distance), determine their magnesium-rich composition (x = 0.01 ± 0.001) and show that they make up 3.6 ± 1.0 per cent of the total dust mass. These values are strikingly similar to those for the dust emitted by the most primitive comets in the Solar System, even though ß Pictoris is more massive and more luminous and has a different planetary system architecture.

Warm water vapour in the sooty outflow from a luminous carbon star.

The detection of circumstellar water vapour around the ageing carbon star IRC +10216 challenged the current understanding of chemistry in old stars, because water was predicted to be almost absent in carbon-rich stars. Several explanations for the water were postulated, including the vaporization of icy bodies (comets or dwarf planets) in orbit around the star, grain surface reactions, and photochemistry in the outer circumstellar envelope. With a single water line detected so far from this one carbon-rich evolved star, it is difficult to discriminate between the different mechanisms proposed. Here we report the detection of dozens of water vapour lines in the far-infrared and sub-millimetre spectrum of IRC +10216 using the Herschel satellite. This includes some high-excitation lines with energies corresponding to approximately 1,000 K, which can be explained only if water is present in the warm inner sooty region of the envelope. A plausible explanation for the warm water appears to be the penetration of ultraviolet photons deep into a clumpy circumstellar envelope. This mechanism also triggers the formation of other molecules, such as ammonia, whose observed abundances are much higher than hitherto predicted.

Emission lines due to ionizing radiation from a compact object in the remnant of Supernova 1987A.

The nearby Supernova 1987A was accompanied by a burst of neutrino emission, which indicates that a compact object (a neutron star or black hole) was formed in the explosion. There has been no direct observation of this compact object. In this work, we observe the supernova remnant with JWST spectroscopy, finding narrow infrared emission lines of argon and sulfur. The line emission is spatially unresolved and blueshifted in velocity relative to the supernova rest frame. We interpret the lines as gas illuminated by a source of ionizing photons located close to the center of the expanding ejecta. Photoionization models show that the line ratios are consistent with ionization by a cooling neutron star or a pulsar wind nebula. The velocity shift could be evidence for a neutron star natal kick.

η CARINAE'S DUSTY HOMUNCULUS NEBULA FROM NEAR-INFRARED TO SUBMILLIMETER WAVELENGTHS: MASS, COMPOSITION, AND EVIDENCE FOR FADING OPACITY.

Infrared observations of the dusty, massive Homunculus Nebula around the luminous blue variable η Carinae are crucial to characterize the mass-loss history and help constrain the mechanisms leading to the Great Eruption. We present the 2.4 - 670 µm spectral energy distribution, constructed from legacy ISO observations and new spectroscopy obtained with the Herschel Space Observatory. Using radiative transfer modeling, we find that the two best-fit dust models yield compositions which are consistent with CNO-processed material, with iron, pyroxene and other metal-rich silicates, corundum, and magnesium-iron sulfide in common. Spherical corundum grains are supported by the good match to a narrow 20.2 µm feature. Our preferred model contains nitrides AlN and Si3N4 in low abundances. Dust masses range from 0.25 to 0.44 M ʘ but M tot ≥ 45 M ʘ in both cases due to an expected high Fe gas-to-dust ratio. The bulk of dust is within a 5″ × 7″ central region. An additional compact feature is detected at 390 µm. We obtain L IR = 2.96 × 106 L ʘ, a 25% decline from an average of mid-IR photometric levels observed in 1971-1977. This indicates a reduction in circumstellar extinction in conjunction with an increase in visual brightness, allowing 25-40% of optical and UV radiation to escape from the central source. We also present an analysis of 12CO and 13CO J = 5 - 4 through 9 - 8 lines, showing that the abundances are consistent with expectations for CNO-processed material. The [12C II] line is detected in absorption, which we suspect originates in foreground material at very low excitation temperatures.

Observations on the effects of barite on the gill tissues of the suspension feeder Cerastoderma edule (Linné) and the deposit feeder Macoma balthica (Linné).

Barite, an important component of offshore drilling muds, is shown to adversely affect the ctenidia of the suspension feeding bivalve, Cerastoderma edule and the deposit feeder, Macoma balthica. SEM observations showed that exposure to barite caused cilia to shorten and coagulate, and, in some extreme cases, cause the disintegration of the gill structure itself. Using a simple ciliary condition index (CCI) the impact of the barite was quantified and damage rates expressed. The bivalves were treated with daily doses of 1, 2, and 3-mm depth equivalents of barite. In all treatments significant damage to the gills was recorded although, in the case of the 1-mm dose rate, this did not occur for 4 days. In the other two treatments, damage was apparent within a day of exposure with 100% mortality occurring within 12 days. Macoma balthica appeared slightly more tolerant of exposure to barite than C. edule.

Discovery of Time Variation of the Intensity of Molecular Lines in IRC+10216 in The Submillimeter and Far Infrared Domains.

We report on the discovery of strong intensity variations in the high rotational lines of abundant molecular species towards the archetypical circumstellar envelope of IRC+10216. The observations have been carried out with the HIFI instrument on board Herschel and with the IRAM 30-m telescope. They cover several observing periods spreading over 3 years. The line intensity variations for molecules produced in the external layers of the envelope most probably result from time variations in the infrared pumping rates. We analyze the main implications this discovery has on the interpretation of molecular line emission in the envelopes of Mira-type stars. Radiative transfer calculations have to take into account both the time variability of infrared pumping and the possible variation of the dust and gas temperatures with stellar phase in order to reproduce the observation of molecular lines at different epochs. The effect of gas temperature variations with stellar phase could be particularly important for lines produced in the innermost regions of the envelope. Each layer of the circumstellar envelope sees the stellar light radiation with a different lag time (phase). Our results show that this effect must be included in the models. The sub-mm and FIR lines of AGB stars cannot anymore be considered as safe intensity calibrators.

Detection of a noble gas molecular ion, 36ArH+, in the Crab Nebula.

Noble gas molecules have not hitherto been detected in space. From spectra obtained with the Herschel Space Observatory, we report the detection of emission in the 617.5- and 1234.6-gigahertz J = 1-0 and 2-1 rotational lines of (36)ArH(+) at several positions in the Crab Nebula, a supernova remnant known to contain both molecular hydrogen and regions of enhanced ionized argon emission. Argon-36 is believed to have originated from explosive nucleosynthesis in massive stars during core-collapse supernova events. Its detection in the Crab Nebula, the product of such a supernova event, confirms this expectation. The likely excitation mechanism for the observed (36)ArH(+) emission lines is electron collisions in partially ionized regions with electron densities of a few hundred per centimeter cubed.

Herschel detects a massive dust reservoir in supernova 1987A.

We report far-infrared and submillimeter observations of supernova 1987A, the star whose explosion was observed on 23 February 1987 in the Large Magellanic Cloud, a galaxy located 160,000 light years away. The observations reveal the presence of a population of cold dust grains radiating with a temperature of about 17 to 23 kelvin at a rate of about 220 times the luminosity of the Sun. The intensity and spectral energy distribution of the emission suggest a dust mass of about 0.4 to 0.7 times the mass of the Sun. The radiation must originate from the supernova ejecta and requires the efficient precipitation of all refractory material into dust. Our observations imply that supernovae can produce the large dust masses detected in young galaxies at very high redshifts.

Massive-star supernovae as major dust factories.

We present late-time optical and mid-infrared observations of the Type II supernova 2003gd in the galaxy NGC 628. Mid-infrared excesses consistent with cooling dust in the ejecta are observed 499 to 678 days after outburst and are accompanied by increasing optical extinction and growing asymmetries in the emission-line profiles. Radiative-transfer models show that up to 0.02 solar masses of dust has formed within the ejecta, beginning as early as 250 days after outburst. These observations show that dust formation in supernova ejecta can be efficient and that massive-star supernovae could have been major dust producers throughout the history of the universe.

Rotational frequencies of methyl group tunneling.

Methyl tunnel frequencies, measured at 4 K, are found to be 455 +/- 8 kHz in methyl malonamide and 496 +/- 8 kHz in methyl ethyl ketone. The first is unaffected by deuteration of the amide groups. Measurements of the temperature dependence of the spin lattice relaxation time are also reported for methyl malonamide and a further test is made of a previously reported correlation between tunnel frequency and the temperature of the T1 minimum. The measurements are in good agreement with the universal correlation curve.

Studies of 16-androstenes in an infant with virilizing adrenal carcinoma.

An 18-month-old girl with virilization was found to have an encapsulated right adrenal carcinoma (2 x3 cm) with great variation in nuclear size, frequent mitoses, and possible blood vessel invasion. Preoperative urinary excretions of 17-ketosteroids, androsterone, etiocholanolone, dehydroepiandrosterone, testosterone, pregnanetriol, 3alpha-androstenol, and 3 beta-androstadienol were elevated; all showed a noticeable decrease postoperatively. Cortisol acetate, given preoperatively, produced a definite decrease in the urinary excretion of 17-ketosteroids and dehydroepiandrosterone; administration of corticotropin resulted in an increase in levels of urinary 17-ketosteroids, 17-hydroxycorticosteroids, and pregnanetriol. Urinary testosterone and 3beta-androstadienol may have diagnostic value since neither was suppressed by cortisol therapy. The behavior of both 3alpha-androstenol and 3beta-androstadienol in this study suggests that they are of adrenal origin.

Production of human monoclonal antibody to rhesus D antigen.

Peripheral-blood mononuclear cells from an individual known to produce antibody to the rhesus D blood group were enriched for specific antibody-producing cells before transformation with Epstein-Barr virus. An anti-rhesus-D antibody-producing cell line (UCH D4) was obtained and cloned. Culture supernatants contained about 20 micrograms/ml of rhesus-D-specific IgG-class antibody. The antibody reactivity compared well with that of reagents used routinely for rhesus blood-grouping.

Detection of carbonates in dust shells around evolved stars.

Carbonates on large Solar System bodies like Earth and Mars (the latter represented by the meteorite ALH84001) form through the weathering of silicates in a watery (CO3)2- solution. The presence of carbonates in interplanetary dust particles and asteroids (again, represented by meteorites) is not completely understood, but has been attributed to aqueous alteration on a large parent body, which was subsequently shattered into smaller pieces. Despite efforts, the presence of carbonates outside the Solar System has hitherto not been established. Here we report the discovery of the carbonates calcite and dolomite in the dust shells of evolved stars, where the conditions are too primitive for the formation of large parent bodies with liquid water. These carbonates, therefore, are not formed by aqueous alteration, but perhaps through processes on the surfaces of dust or ice grains or gas phase condensation. The presence of carbonates which did not form by aqueous alteration suggests that some of the carbonates found in Solar System bodies no longer provide direct evidence that liquid water was present on large parent bodies early in the history of the Solar System.