Dust-to-gas ratio resurgence in circumstellar disks due to the formation of giant planets: the case of HD 163296

The amount of dust present in circumstellar disks is expected to steadily decrease with age due to the growth from micron-sized particles to planetesimals and planets. Mature circumstellar disks, however, can be observed to contain significant amounts of dust and possess high dust-to-gas ratios. Using HD 163296 as our case study, we explore how the formation of giant planets in disks can create the conditions for collisionally rejuvenating the dust population, halting or reversing the expected trend. We combine N-body simulations with statistical methods and impact scaling laws to estimate the dynamical and collisional excitation of the planetesimals due to the formation of HD 163296's giant planets. We show that this process creates a violent collisional environment across the disk that can inject collisionally produced second-generation dust into it, significantly contributing to the observed dust-to-gas ratio. The spatial distribution of the dust production can explain the observed local enrichments in HD 163296's inner regions. The results obtained for HD 163296 can be extended to any disk with embedded forming giant planets and may indicate a common evolutionary stage in the life of such circumstellar disks. Furthermore, the dynamical excitation of the planetesimals could result in the release of transient, non-equilibrium gas species like H2O, CO2, NH3 and CO in the disk due to ice sublimation during impacts and, due to the excited planetesimals being supersonic with respect to the gas, could produce bow shocks in the latter that could heat it and cause a broadening of its emission lines.Comment: 18 pages, 9 figures, 2 tables. Accepted for publication on The Astrophysical Journa

Olivine on Vesta as exogenous contaminants brought by impacts: Constraints from modeling Vesta's collisional history and from impact simulations

The survival of asteroid Vesta during the violent early history of the Solar System is a pivotal constraint on theories of planetary formation. Particularly important from this perspective is the amount of olivine excavated from the vestan mantle by impacts, as this constrains both the interior structure of Vesta and the number of major impacts the asteroid suffered during its life. The NASA Dawn mission revealed that olivine is present on Vesta's surface in limited quantities, concentrated in small patches at a handful of sites and interpreted as the result of the excavation of endogenous olivine. Later works raised the possibility that the olivine had an exogenous origin, based on the geologic and spectral features of the deposits. In this work we quantitatively explore the proposed scenario of a exogenous origin for the detected olivine to investigate whether its presence on Vesta can be explained as a natural outcome of the collisional history of the asteroid. We took advantage of the impact contamination model previously developed to study the origin and amount of dark and hydrated materials observed by Dawn on Vesta, which we updated by performing dedicated hydrocode impact simulations. We show that the exogenous delivery of olivine by impacts can offer a viable explanation for the currently identified olivine-rich sites without violating the constraint posed by the lack of global olivine signatures on Vesta. Our results indicate that no mantle excavation is in principle required to explain the observations of the Dawn mission and support the idea that the vestan crust could be thicker than indicated by simple geochemical models based on the Howardite-Eucrite-Diogenite family of meteorites.Comment: 24 pages, 6 figures, accepted for publication on the journal Icaru

A new perspective on the irregular satellites of Saturn - II Dynamical and physical origin

The origin of the irregular satellites of the giant planets has been long debated since their discovery. Their dynamical features argue against an in-situ formation suggesting they are captured bodies, yet there is no global consensus on the physical process at the basis of their capture. In this paper we explore the collisional capture scenario, where the actual satellites originated from impacts occurred within Saturn's influence sphere. By modeling the inverse capture problem, we estimated the families of orbits of the possible parent bodies and the specific impulse needed for their capture. The orbits of these putative parent bodies are compared to those of the minor bodies of the outer Solar System to outline their possible region of formation. Finally, we tested the collisional capture hypothesis on Phoebe by taking advantage of the data supplied by Cassini on its major crater, Jason. Our results presented a realistic range of solutions matching the observational and dynamical data.Comment: 26 Pages, 21 Figure

Habitable Planet Formation in Binary-Planetary Systems

Recent radial velocity observations have indicated that Jovian-type planets can exist in moderately close binary star systems. Numerical simulations of the dynamical stability of terrestrial-class planets in such environments have shown that, in addition to their giant planets, these systems can also harbor Earth-like objects. In this paper, we study the late stage of terrestrial planet formation in such binary-planetary systems, and present the results of the simulations of the formation of Earth-like bodies in their habitable zones. We consider a circumprimary disk of Moon- to Mars-sized objects and numerically integrate the orbits of these bodies at the presence of the Jovian-type planet of the system and for different values of the mass, semimajor axis, and orbital eccentricity of the secondary star. Results indicate that, Earth-like objects, with substantial amounts of water, can form in the habitable zone of the primary star. Simulations also indicate that, by transferring angular momentum from the secondary star to protoplanetary objects, the giant planet of the system plays a key role in the radial mixing of these bodies and the water contents of the final terrestrial planets. We will discuss the results of our simulation and show that the formation of habitable planets in binary-planetary systems is more probable in binaries with moderate to large perihelia.Comment: 27 pages, 11 figures, submitted for publicatio

The late accretion and erosion of Vesta's crust recorded by eucrites and diogenites as an astrochemical window into the formation of Jupiter and the early evolution of the Solar System

For decades the limited thickness of Vesta's basaltic crust, revealed by the link between the asteroid and the howardite-eucrite-diogenite family of meteorites, and its survival to collisional erosion offered an important constraint for the study of the early evolution of the Solar System. Some results of the Dawn mission, however, cast doubts on our understanding of Vesta's interior composition and of the characteristics of its basaltic crust, weakening this classical constraint. In this work we investigate the late accretion and erosion experienced by Vesta's crust after its differentiation and recorded in the composition of eucrites and diogenites and show that it offers an astrochemical window into the earliest evolution of the Solar System. In our proof-of-concept case study focusing on the late accretion and erosion of Vesta's crust during the growth and migration of Jupiter, the water enrichment of eucrites appears to be a sensitive function of Jupiter's migration while the enrichment in highly-siderophile elements of diogenites appears to be particularly sensitive to the size-frequency distribution of the planetesimals. The picture depicted by the enrichments created by late accretion in eucrites and diogenites is not qualitatively affected by the uncertainty on the primordial mass of Vesta. Crustal erosion, instead, is more significantly affected by said uncertainty and Vesta's crust survival appears to be mainly useful to study violent collisional scenarios where highly energetic impacts can strip significant amounts of vestan material while limitedly contributing to Vesta's late accretion. Our results suggest that the astrochemical record of the late accretion and erosion of Vesta's crust provided by eucrites and diogenites can be used as a tool to investigate any process or scenario associated to the evolution of primordial Vesta and of the early Solar System.Comment: 21 pages, 15 figures, accepted for publication on Icaru

PENGARUH PEMBERIAN EKSTRAK KUNYIT (Curcuma domestica)DAN PENAMBAHAN ONGGOK TERFERMENTASI DALAM RANSUM TERHADAP PERFORMANS DARAH DAN METABOLIT LEMAK DARAH AYAM BROILER

ABSTRAK Penelitian bertujuan untuk mengetahui pengaruhpemberian ekstrak kunyit peroral dan penambahan onggok fermentasi pada ransum terhadap performans hematologi dan kadar metabolit lemak darah ayam broiler. Materi penelitian adalah ayam broiler strain Lohman umur 2 minggu sebanyak 96 ekor rataan bobot awal385±63,93 gram. Ransum jadi BR1 untuk periode starterdan BR2 untuk periode finisher. Rancangan percobaan yang digunakan adalah rancangan acak lengkap faktorial 2x3. Faktor A:ekstrak kunyit (200 dan 400 mg/kg bb/2 hari) dan faktor B: onggok fermentasi (0, 5 dan 10 % dari ransum), diulang 4 kali setiap ulangan terdiri 4 ekor. Variabel yang diamati jumlah eritrosit, kadar hemoglobin, hematokrit, kolesterol, HDL dan LDLdarah ayam broiler. Hasil penelitian menunjukkan bahwa tidak ada pengaruh interaksi antara ekstrak kunyit dengan onggok fermentasi. Secara terpisah, ekstrak kunyit dan onggok fermentasi masing-masing tidak berpengaruh terhadap rataan jumlah eritrosit, kadar hemoglobin, hematokrit, kolesterol, dan HDL, namun berpengaruh nyata (P<0,05) terhadap rataan LDLdarah ayam broiler. Kata kunci : ekstrak kunyit, onggok fermentasi, performans darah, metabolit lemak darah, ayam broile

Pengaruh Penambahan Probiotik Rhizopus Oryzae Terhadap Total Mikroba Usus Halus Dan Seka Ayam Kampung Periode Grower (the Effect of Probiotic Rhizopus Oryzae Administrationon the Total Number of Microbes in the Small Intestine and Caeca of Kampoeng Chicke

The purpose of this study was to investigate the effect of probiotic Rhizopus oryzaeadministration on the total number of microbes in the smallintestine and caeca of kampoengchickens during the growerperiod. The study was conducted on 11 August to 11 October 2014 in the poultry farm at the Faculty of Animal and Agricultural Sciences, Diponegoro University.The materials used in this study were 100 Day Old Chick (DOC) (unsexed) with initial body weight of 37.90 ± 1,36 g.The experiment was set asCompletely Randomized Design (CRD).The treatments consisted of T0 (control), T1 (0.1% addition of probiotic Rhizopus oryzae to the diet) and T2 (0.2% addition of probiotic Rhizopus oryzae to the diet).The results showed that addition of probioticRhizopus oryzae in the diet did not affect (P&gt;0.05) the total number of microbesin the small intestine and caeca ofchicken during the grower period, but affected (P&lt;0.05) the daily gain of chicken within 0-9 weeks.The highest daily gain was observed in T1 which was not different (P&gt;0.05) from T2 but different (P&lt;0.05) from T0.The conclusion of this study was the administration of Rhizopus oryzae with a dose of 0.1 % and 0.2 % in the chicken dietdid not increase the total number of microbes in the small intestine and caeca of kampong chickensduring the grower period, but the additionof Rhizopus oryzae could increase the daily gain at 0-9 weeks of age,at which the highest impact was observed when Rhizopus oryzae was added at 0.1 %