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  • Lepidoptera  (2)
  • Asteroids  (1)
  • 2020-2022  (1)
  • 1980-1984  (2)
  • 1920-1924
  • 1
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    Macroporosity and Grain Density of Rubble Pile Asteroid (162173) Ryugu (2021)
    Details
    Publication Date: 2021-07-04
    Description: Rubble pile asteroids such as (162173) Ryugu have large bulk porosities, which are believed to result from void spaces in between the constituent boulders (macroporosity) as well as void spaces within the boulders themselves (microporosity). In general, both macroporosity and microporosity are estimated based on comparisons between the asteroid bulk density and both the bulk and grain density of meteorite analogs, and relatively large macroporosities are usually obtained. Here we use semiempirical models for the macroporosity of multicomponent mixtures to determine Ryugu's macroporosity based on the observed size‐frequency distribution (SFD) of boulders on the surface. We find that Ryugu's macroporosity can be significantly smaller than usually assumed, as the observed SFD allows for an efficient packing of boulders, resulting in a macroporosity of 16% ± 3%. Therefore, we confirm that Ryugu's high bulk porosity is a direct consequence of a very large boulder microporosity. Furthermore, using estimates of boulder microporosity of around 50% as derived from in situ measurements, the average grain density in boulders is 2,848 ± 152 kg m–3, similar to values obtained for CM and the Tagish lake meteorites. Ryugu's bulk porosity corresponding to the above values is 58%. Thus, the macroporosity of rubble pile asteroids may have been systematically overestimated in the past.
    Description: Plain Language Summary: The carbonaceous asteroid (162173) Ryugu formed from fragments which reaccreted after its parent body was disrupted by a catastrophic collision. Asteroids of this type are also known as rubble piles and the reaccumulation process is thought to be one of the causes for their large bulk porosity. We have applied mixing models to determine the amount of interboulder porosity taking the observed abundance of large and small boulders on the surface into account. We find that the relative abundances of differently sized boulders allow for a very efficient packing, such that interboulder porosity in Ryugu is rather small and only 16% ± 3%. This implies that a large part of Ryugu's total porosity must reside inside the boulders themselves. Using estimates of boulder intrinsic porosity, we furthermore constrain the average density of the boulder's constituent minerals to 2,848 ± 152 kg m−3, which is consistent with values measured for carbonaceous meteorites as collected on Earth. Thus, interboulder porosity of rubble pile asteroids may have been systematically overestimated in the past.
    Description: Key Points: Ryugu's large bulk porosity is distributed between intrinsic boulder microporosity and macroporosity due to void spaces in‐between boulders. We use the boulder size‐frequency distribution as observed on the surface together with mixing models to estimate Ryugu's macroporosity. We find that macroporosity is 16% ± 3%, indicating that Ryugu's large bulk porosity of close to 50% is governed by microporosity.
    Keywords: 523 ; Asteroids ; Ryugu ; Porosity ; Density
    Type: article
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    CITATION GEO-LEO
  • 2
    Electronic Resource
    Electronic Resource
    Odor of a papilionid butterfly (1980)
    Springer
    Journal of chemical ecology 6 (1980), S. 867-873 
    Details
    ISSN: 1573-1561
    Keywords: Male scent ; Atrophaneura alcinous ; Lepidoptera ; Papilionidae ; benzaldehyde ; phenylacetaldehyde ; 2-phenylpropenal ; n-heptanal ; 6-methylhept-5-en-2-one ; linalool
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Benzaldehyde, phenylacetaldehyde (major component), 2-phenylpropenal,n-heptanal, 6-methylhept-5-en-2-one, and linalool were identified as compounds responsible for the male scent ofAtrophaneura alcinous alcinous. These substances were present predominantly in the wings, and the quantity of them was largest at the inner margin of the hind wing. Female wings also contained some of them in much smaller (except a few components) amounts. The relative proportion of each component exhibited manifests sexual differences.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00990470
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  • 3
    Electronic Resource
    Electronic Resource
    Larval osmeterial secretions of the swallowtails (Papilio) (1981)
    Springer
    Journal of chemical ecology 7 (1981), S. 1089-1113 
    Details
    ISSN: 1573-1561
    Keywords: Osmeterial secretion ; Papilio larvae ; Lepidoptera ; monoterpene ; sesquiterpene ; aliphatic acid ; ester
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The larval osmeterial secretions of sixPapilio species examined displayed a remarkable qualitative change at the fourth larval ecdysis. The secretions of 4th (penultimate) instar larvae ofP. machaon, P. memnon, P. helenus, P. bianor, andP. maackii principally comprised mono- and/or sesquiterpenoids. The compounds identified from these species included α-pinene, sabinene, β-myrcene, limonene, β-phellandrene, (Z)-β-ocimene, (E)-β-ocimene, β-elemene, β-caryophyllene, (E)-β-farnesene, β-selinene, (E,E)-α-farnesene, germacrene-A, germacrene-B, caryophyllene oxide, methyl 3-hydroxy-n-butyrate, and acetic acid. In contrast, the secretion of 4th larval instar ofP. xuthus, although containing similar terpenic compounds, was accompanied by large amounts of aliphatic acids and their esters: isobutyric acid, 2-methylbutyric acid, methyl isobutyrate and methyl 2-methylbutyrate. On the other hand, the osmeterial secretions of 5th (last) instar larvae varied little in quality among the six species, and the identified compounds consisted of isobutyric acid, 2-methylbutyric acid, methyl isobutyrate, ethyl isobutyrate, methyl 2-methylbutyrate, ethyl 2-methylbutyrate, and isovaleric acid, the last of which was specific toP. bianor andP. maackii. The chemical alteration of osmeterial exudate synchronized at the final larval ecdysis with the larval morphological change (particularly in body coloration) that appears to be of defensive significance against predators.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00987631
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