68 research outputs found
Tidally locked rotation of the dwarf planet (136199) Eris discovered from long-term ground based and space photometry
The rotational states of the members in the dwarf planet - satellite systems
in the transneptunian region are determined by the formation conditions and the
tidal interaction between the components, and these rotational characteristics
are the prime tracers of their evolution. Previously a number of authors
claimed highly diverse values for the rotation period for the dwarf planet
Eris, ranging from a few hours to a rotation (nearly) synchronous with the
orbital period (15.8 d) of its satellite, Dysnomia. In this letter we present
new light curve data of Eris, taken with 1-2m-class ground based
telescopes, and with the TESS and Gaia space telescopes. TESS data could not
provide a well-defined light curve period, but could constrain light curve
variations to a maximum possible light curve amplitude of
0.03 mag (1-) for P 24 h periods. Both the combined ground-based
data and the Gaia measurements unambiguously point to a light curve period
equal to the orbital period of Dysnomia, P = 15.8 d, with a light curve
amplitude of 0.03 mag, i.e. the rotation of Eris is
tidally locked. Assuming that Dysnomia has a collisional origin, calculations
with a simple tidal evolution model show that Dysnomia has to be relatively
massive (mass ratio of q = 0.01--0.03) and large (radius of 300
km) to slow down Eris to synchronized rotation. These simulations also indicate
that -- assuming tidal parameters usually considered for transneptunian objects
-- the density of Dysnomia should be 1.8-2.4 , an exceptionally high
value among similarly sized transneptunian objects, putting important
constraints on the formation conditions.Comment: Accepted for publication in Astronomy and Astrophysics Letters, data
of tables A.1, A.2 and A.4 are available at
https://cloud.konkoly.hu/s/ESiKi4GZyifJmj
Olivine major and trace element compositions coupled with spinel chemistry to unravel the magmatic systems feeding monogenetic basaltic volcanoes
Monogenetic basaltic volcanic systems, despite their considerable smaller size and shorter lifetime compared to polygenetic volcanoes, can have complex pre-eruptive histories and composite volcanic facies
architectures. Their source-to-surface investigation is essential for our better understanding of monogenetic volcanism and requires high-resolution mineral-scale analyses.
In this study, we focus on diversely zoned olivine crystals and their spinel inclusions from alkaline basaltic volcanics that are the result of mixing of numerous magmas, crystals and fragments of various origins. The
Fekete-hegy volcanic complex is one of the largest and most composite eruptive centers in the intracontinental monogenetic Bakony–Balaton Highland Volcanic Field (western Pannonian Basin, Eastern Central Europe). It is a
compound multi-vent system built up by multiple eruption episodes: initial maar-forming phreatomagmatic eruptions were followed by massive lava flows and magmatic explosive activity. We performed stratigraphically
controlled sampling in order to reveal the history of the successively erupted magma batches represented by the distinct eruptive units, as well as to discover the petrogenetic processes that controlled the evolution of the
magmatic system.
The juvenile pyroclasts of the phreatomagmatic eruption products (unit 1) contain a remarkably diverse mineral assemblage including five different olivine types and three distinct spinel groups. In addition, they
comprise various xenoliths. Based on detailed textural investigations combined with in situ electron microprobe analyses, high-resolution laser ablation ICP-MS trace element mapping and single spot measurements on the variably zoned olivines of unit 1 samples, eight distinct environments are inferred to have been involved in their formation. Four of these environments account for the significant compositional variation of the olivine-hosted
spinel inclusions. A complex set of open- and closed-system petrogenetic processes operated during the evolution of the magmatic system: magma stalling, accumulation, storage, fractionation, mixing, replenishments,
cumulate remobilization, incorporation of foreign fragments and crystals from the wall rocks. All these diverse environments and processes resulted in the mixed character of the erupted magmas during the initial
phreatomagmatic eruptive phase.
In contrast, the uniform petrological features and the small variations shown by the olivines and spinels from unit 2‐–3 indicate that the later magmatic explosive – effusive phase was preceded by a considerable change
in the magmatic system; it experienced a simple evolution through olivine + spinel fractional crystallization without any of the complexities seen during the initial phase.
The present study emphasizes the importance of high-resolution mineral-scale textural and chemical investigations to unravel the complexity of the sub-volcanic magmatic systems feeding monogenetic basaltic
volcanoes. Compared to the application of whole-rock geochemistry alone, this approach enables a direct and more detailed insight into the architecture and evolution of these systems
Complexity of equational theory of relational algebras with standard projection elements
The class of t rue p airing a lgebras is defined to be the class of relation algebras expanded with concrete set theoretical projection functions. The main results of the present paper is that neither the equational theory of nor the first order theory of are decidable. Moreover, we show that the set of all equations valid in is exactly on the level. We consider the class of the relation algebra reducts of ’s, as well. We prove that the equational theory of is much simpler, namely, it is recursively enumerable. We also give motivation for our results and some connections to related work
Discovery of nucleotide polymorphisms in the Musa gene pool by Ecotilling
Musa (banana and plantain) is an important genus for the global export market and in local markets where it provides staple food for approximately 400 million people. Hybridization and polyploidization of several (sub)species, combined with vegetative propagation and human selection have produced a complex genetic history. We describe the application of the Ecotilling method for the discovery and characterization of nucleotide polymorphisms in diploid and polyploid accessions of Musa. We discovered over 800 novel alleles in 80 accessions. Sequencing and band evaluation shows Ecotilling to be a robust and accurate platform for the discovery of polymorphisms in homologous and homeologous gene targets. In the process of validating the method, we identified two single nucleotide polymorphisms that may be deleterious for the function of a gene putatively important for phototropism. Evaluation of heterozygous polymorphism and haplotype blocks revealed a high level of nucleotide diversity in Musa accessions. We further applied a strategy for the simultaneous discovery of heterozygous and homozygous polymorphisms in diploid accessions to rapidly evaluate nucleotide diversity in accessions of the same genome type. This strategy can be used to develop hypotheses for inheritance patterns of nucleotide polymorphisms within and between genome types. We conclude that Ecotilling is suitable for diversity studies in Musa, that it can be considered for functional genomics studies and as tool in selecting germplasm for traditional and mutation breeding approaches
Origin and ascent history of unusually crystal-rich alkaline basaltic magmas from the western Pannonian Basin
The last eruptions of the monogenetic Bakony-Balaton Highland Volcanic Field
(western Pannonian Basin, Hungary) produced unusually crystal- and xenolith-rich
alkaline basalts which are unique among the alkaline basalts of the Carpathian-
Pannonian Region. Similar alkaline basalts are only rarely known in other volcanic
fields of the world. These special basaltic magmas fed the eruptions of two closely
located volcanic centres: the Bondoró-hegy and the Füzes-tó scoria cone. Their
uncommon enrichment in diverse crystals produced unique rock textures and modified
original magma compositions (13.1-14.2 wt.% MgO, 459-657 ppm Cr, 455-564 ppm Ni
contents).
Detailed mineral-scale textural and chemical analyses revealed that the Bondoró-hegy
and Füzes-tó alkaline basaltic magmas have a complex ascent history, and that most
of their minerals (~30 vol.% of the rocks) represent foreign crystals derived from
different levels of the underlying lithosphere. The most abundant xenocrysts, olivine,
orthopyroxene, clinopyroxene and spinel, were incorporated from different regions and
rock types of the subcontinental lithospheric mantle. Megacrysts of clinopyroxene and
spinel could have originated from pegmatitic veins / sills which probably represent
magmas crystallized near the crust-mantle boundary. Green clinopyroxene xenocrysts
could have been derived from lower crustal mafic granulites. Minerals that crystallized
in situ from the alkaline basaltic melts (olivine with Cr-spinel inclusions, clinopyroxene,
plagioclase, Fe-Ti oxides) are only represented by microphenocrysts and overgrowths
on the foreign crystals. The vast amount of peridotitic (most common) and mafic
granulitic materials indicates a highly effective interaction between the ascending
magmas and wall rocks at lithospheric mantle and lower crustal levels. However,
fragments from the middle and upper crust are absent from the studied basalts,
suggesting a change in the style (and possibly rate) of magma ascent in the crust.
These xenocryst- and xenolith-rich basalts yield divers tools for estimating magma
ascent rate that is important for hazard forecasting in monogenetic volcanic fields.
According to the estimated ascent rates, the Bondoró-hegy and Füzes-tó alkaline
basaltic magmas could have reached the surface within hours to few days, similarly to
the estimates for other eruptive centres in the Pannonian Basin which were fed by
"normal" (crystal- and xenolith-poor) alkaline basalts
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