Oral Histories in Meteoritics and Planetary Science—XXIII: Dieter Stöffler

In this interview, Dieter Stöffler (Fig. 1) describes how his interest in meteorites and impact craters dates from his Ph.D. studies at the University of Tübingen when it was learned that the Ries crater was formed by impact. A paper by Dieter's advisor, Wolf von Engelhardt, also triggered an interest in meteorites. After graduation, Dieter helped to establish a laboratory for high pressure mineralogy and he examined rocks from the Ries crater, which led to the concept of progressive shock metamorphism. The group also worked on newly returned Apollo samples and guided astronauts over the crater. A year at the NASA Ames Research Center taught Dieter about experimental impact research with a light‐gas gun. After a few more years at Tübingen, Dieter obtained a professorship at the University of Münster where he created the Institute of Planetology, got involved in planning space missions including comet sample return, and continued high pressure mineralogy in collaboration with colleagues in Freiburg. Through several decades of research, Dieter and colleagues have documented the effects of shock on all the major rock‐forming minerals and devised widely accepted schemes for the classification of shocked rocks. After the unification of Germany, Dieter became Director of the Natural History Museum in Berlin, during which he made much progress rebuilding the laboratories and the collections. Dieter also helped to create a museum and research center in the Ries crater. He received the Barringer Award of the Meteoritical Society in 1994 and several prestigious awards in Germany.     

Zur Entwicklung von Galaxien unter Berücksichtigung von Stößen gasförmiger Wolken

BROSCHE'S investigations concerning the evolution of galaxies are repeated using values for the starting-point which deviate from that of BROSCHE. Especially, a protogalaxy is assumed to consist of gas clouds each of them having a mass of 10⁵ M⊙. The comparison of the results with observation is satisfactory. BROSCHE's interpretation of the HUBBLE sequence as a sequence depending on the angular momentum seems to be questionable.     

Addendum to “Stöffler,D., Hamann,C., and Metzler,K., Shock metamorphism of planetary silicate rocks and sediments: Proposal for an updated classification system. Meteoritics & Planetary Science 53, 5–49, 2018”

With this addendum we provide some correction and additional information regarding the above cited publication. It addresses the following two topics. (1) Clarification for a correct application of the criteria for certain shock stages of chondrites, in particular stage C‐S6. (2) Correction of a printing error in the table that contains the shock classification system of chondrites.     

Relationen zwischen Störungen des lokalen Temperaturfeldes und den geodätisch-astronomischen Beobachtungsresultaten am Astrolab DANJON (Mitteilungen des Zentralinstituts für Physik der Erde,Nr. 955)

The long-term series of geodetic-astronomical observations are an important data basis for geodynamic investigations, but the microclimatic influence on their results is an uncontested fact too. The local topography brings about thermal anomalies and thus it is the cause of the inclination of isopycenics and refraction disturbances. The measuring equipment is described for the temperature registration near the astrolabe DANJON at the observatory Potsdam. It is reported on quality and treatment of measuring dates and on design of the graphic temperature-model. In the 6-metre plane, horizontal temperature gradients were determined in the azimuth of all stars observed. They yield direct information about the thermally caused inclination of the layers of equal density in the differentially small region which is passed by the beam of light coming from the star. The correlation between these gradients and the geodetic-astronomical observations are detected. The corrections produced on the basis of the regression analysis are computed for significant correlations (about 30%). An improvement and extension of the temperature recorder is discussed with a view to a higher effect of this method.     

Rapid weathering in Holbrook: An iron-57 Mössbauer spectroscopy study

Abstract— Samples of Holbrook (an L6 chondrite that fell in Arizona in 1912) were analysed by ⁵⁷Fe Mössbauer spectroscopy to determine the proportion of the total Fe that had been converted to Fe³⁺ by weathering processes. Although samples recovered in 1912 showed negligible (<1%) alteration, a spectrum recorded from a specimen recovered in 1968 showed that 9.7% of the total Fe was present as Fe³⁺. Given the existence of samples in similar semiarid environments with terrestrial ages >40 ka, a linear rate of weathering is unrealistic, rapidly producing very high levels of oxidation in samples with low terrestrial ages. However if weathering follows an approximate power law, then we can model a rapid initial phase and the levels of oxidation that are more typical in samples with much longer terrestrial residence times recovered from Roosevelt County. Our analysis, together with work on terrestrial age dated samples, indicates that hot desert weathering of ordinary chondrites is at least a two-stage process, with an initial rapid phase lasting <500 years before oxidation is passivated.     

An embedded exponentially fitted Runge–Kutta–Nyström method for the numerical solution of orbital problems

A new embedded pair of explicit exponentially fitted Runge–Kutta–Nyström methods is constructed. The methods integrate exactly systems of differential equations whose solutions are linear combinations of the functions from the set {exp(μt), exp(−μt)} (). The pair has four stages and algebraic orders five and three. An application to some well-known orbital problem shows that the new pair is very competitive when it is compared with high-quality codes proposed in the scientific literature.     

An extended multi-zone model for the MCG–6-30-15 warm absorber

The variable warm absorber seen with ASCA in the X-ray spectrum of MCG–6-30-15 shows complex time behaviour in which the optical depth of O  viii anticorrelates with the flux whereas that of O  vii is unchanging. The explanation in terms of a two-zone absorber has since been challenged by BeppoSAX observations. These present a more complicated behaviour for the O  viii edge. We demonstrate here that the presence of a third, intermediate, zone can explain all the observations. In practice, warm absorbers are likely to be extended, multi-zone regions of which only part causes directly observable absorption edges at any given time.     

THE HAVERÖ UREILITE*

The Haverö ureilite fell on August 2, 1971 on the Island of Haverö, Finland, lat 22° 03‘ 43“ E., long 60° 14’ 44” N. The meteorite contains curved open fractures partly filled with kamacite foils or drops, clusters of olivine mosaic with preferred orientation, very fine-lamellar polysynthetic twinned clino-***bronzite and carbonaceous matter as laths up to 4 mm in length. The carbon laths are in preferred orientation and contain in addition to graphite, kamacite, chromite and diamonds. The petrology, textural features and origin are discussed.     

THE CHEMISTRY OF HAVERÖ UREILITE

The concentrations of 41 major, minor and trace elements were determined in Haverö ureilite. In addition to the analysis on bulk samples a number of separates were measured, too, including hand-picked samples of the dark carbonaceous, diamond-rich inclusions and two metal fractions. It was found that one metal fraction had an extraordinarily high Ir/Au-ratio of 19. According to the concentrations of the noble metals and of nickel, gallium, tungsten and rhenium this metal represents, most probably, the siderophile portion of a high temperature condensate, i.e., the pattern of these elements is very similar to that found in Allende inclusions (Wänke et al., 1972)     

An RXTE observation of the Seyfert 1 galaxy MCG–6-30-15: X-ray reflection and the iron abundance

We report on a 50-ks observation of the bright Seyfert 1 galaxy MCG–6-30-15 with the Rossi X-ray Timing Explorer . The data clearly show the broad fluorescent iron line (equivalent width ∼ 250 eV) and the Compton reflection continuum at higher energies. A comparison of the iron line and the reflection continuum has enabled us to constrain the reflective fraction and the elemental abundances in the accretion disc. Temporal studies provide evidence that spectral variability is a result of changes in both the amount of reflection seen and the properties of the primary X-ray source itself.     

Merging History of Massive Galaxies at 3 < z < 6

The observational data of high redshift galaxies become increasingly abundant, especially since the operation of the James Webb Space Telescope, which allows us to verify and optimize the galaxy formation model at high redshifts. In this work, we investigate the merging history of massive galaxies at 3 < z < 6 using a well-developed semi-analytic galaxy formation catalog. We find that the major merger rate increases with redshift up to 3 and then flattens. The fraction of wet mergers, duri...     

COSMOGENEIC RADIONUCLIDES IN THE HAVERÖ METEORITE

An 87-gram sample of the Haverö ureilite has been analyzed by non-destructive gamma-ray spectrometry. The results of the measurements, in dpm/kg at time of fall, are: ²²Na, 71 ± 3; ²⁶Al, 43 ± 3; ⁴⁶Sc, 3.4 ± 2.1; ⁵⁴Mn, 35 ± 6; ⁶⁰Co, 0.7, 2*** limit. Haverö has 77 ± 14% of the ²⁶Al activity calculated for its chemical composition. When averaged with previously-reported analyses of Goalpara and Novo Urei, ureilites as a class have 74 ± 7% of their expected ²⁶Al activity. The depletion in ²⁶Al could be the coincidental result of identical “shielding” effects in three meteorites of apparently very different preatmospheric sizes. Alternatively, ureilites may have been exposed to a lower cosmic-ray flux than that experienced by most chondrites, probably the result of characteristically different orbits     

ELEMENTAL ABUNDANCES IN THE HAVERÖ METEORITE

Abundances of 15 major, minor and trace elements have been determined in powders and interior chips derived from the Haverö ureilite. The values are in close agreement with mean values for other ureilites, as reported in the literature. The powdered samples exhibited slightly higher abundances of O and Si, than the interior chips. It is suggested that this may be due to alteration of the samples during the powdering process