Antiquark nuggets as dark matter: New constraints and detection prospects

Current evidence for dark matter in the universe does not exclude heavy composite nuclear-density objects consisting of bound quarks or antiquarks over a significant range of masses. Here we analyze one such proposed scenario, which hypothesizes antiquark nuggets with a range of log10(B) = 24-30 with specific predictions for spectral emissivity via interactions with normal matter. We find that, if these objects make up the majority of the dark matter density in the solar neighborhood, their radiation efficiency in solids is marginally constrained, due to limits from the total geothermal energy budget of the Earth. At allowed radiation efficiencies, the number density of such objects can be constrained to be well below dark matter densities by existing radio data over a mass range currently not restricted by other methods.Comment: 6 pages, 3 figures, revised references; submitted to PR

ANALISIS TEGANGAN PADA RANGKA MOBIL BOOGIE

Rangka atau chassis adalah bagian komponen terpenting dari semua kendaraan yang berfungsi sebagai penopang berat kendaraan, mesin serta penumpang. Lintasan yang dilalui mobil boogie adalah lintasan off road, sehingga keamanan penumpang menjadi hal yang sangat diperhatikan. Hal ini menjadi alasan mengapa mobil boogie harus memiliki rangka yang menutupi bagian atas kendaraan sehingga pengemudi akan lebih aman jika terjadi kecelakaan yang fatal. Karena beban terbesar terjadi pada dudukan pengemudi dan mesin, maka perlu dilakukan analisis dikedua dudukan tersebut, dengan menggunakan perangkat lunak Catia V5. Tujuannya untuk mengetahui deformasi yang terjadi serta daerah kritis dari masing-masing jenis dudukan dan vector peralihannya. Setelah proses analisis dilakukan, diperoleh tegangan Von Mises maksimum sebesar 14,1 x 107 N/m2 untuk rangka dudukan pengemudi dan 8.81 x 107 N/m2 untuk rangka dudukan mesin, juga didapatkan vektor peralihan sebesar 0,00528 mm untuk rangka dudukan pengemudi dan 0,0000242 mm untuk rangka dudukan mesin

Impact hazard protection efficiency by a small kinetic impactor

In this paper the ability of a small kinetic impactor spacecraft to mitigate an Earth-threatening asteroid is assessed by means of a novel measure of efficiency. This measure estimates the probability of a space system to deflect a single randomly-generated Earth-impacting object to a safe distance from the Earth. This represents a measure of efficiency that is not biased by the orbital parameters of a test-case object. A vast number of virtual Earth-impacting scenarios are investigated by homogenously distributing in orbital space a grid of 17,518 Earth impacting trajectories. The relative frequency of each trajectory is estimated by means Opik’s theory and Bottke’s near Earth objects model. A design of the entire mitigation mission is performed and the largest deflected asteroid computed for each impacting trajectory. The minimum detectable asteroid can also be estimated by an asteroid survey model. The results show that current technology would likely suffice against discovered airburst and local damage threats, whereas larger space systems would be necessary to reliably tackle impact hazard from larger threats. For example, it is shown that only 1,000 kg kinetic impactor would suffice to mitigate the impact threat of 27.1% of objects posing similar threat than that posed by Apophis

Diversity of morphological characters of 30 local torch ginger accessions from Pangandaran of West Java of Indonesia

Torch ginger (Etlingera spp.) is one of the herbal plants native to Indonesia that has long been known and used as medicines. Exploration on torch ginger plant needs to be done to conservate and determine genetic diversity. Study of genetic diversity torch ginger in the district of Pangandaran is important because as long as there has been no study in depth the potential of genetic diversity and phylogenetic relationship germplasm of torch ginger Genetic diversity based on this research had a proportion of 47% of the total of 100% in the PC1-PC3 was based on the analysis Principal Component Analysis (PCA) with the character influencing that form clumps, line leaf midrib, plant height, stem diameter, leaf length, color scales rhizome, stem color, rhizome and the leaf base forms. Based on the results of the genetic diversity cluster analysis found that narrow torch ginger euclidean indicated by coefficient of 0.79 and was divided into six clusters. Accession which had the closest kinship i.e. accession N1 from Cikadu subdistrict of Cintakarya and accession N2 from Cikoang subdistrict of Cintakarya, while accession with the farthest kinship namely accession N29 from Jangraga subdistrict of Mangunjaya with range euclidean of 0.79

A search for L dwarf binary systems

We present analysis of HST Planetary Camera images of twenty L dwarfs identified in the course of the Two Micron All-Sky Survey. Four of the targets have faint, red companions at separations between 0.07 and 0.29 arcseconds (1.6 to 7.6 AU). In three cases, the bolometric magnitudes of the components differ by less than 0.3 magnitudes. Since the cooling rate for brown dwarfs is a strong function of mass, similarity in luminosities implies comparable masses. The faint component in the 2M0850 system, however, is over 1.3 magnitudes fainter than the primary in the I-band, and ~0.8 magnitudes fainter in M(bol). Indeed, 2M0850B is ~0.8 magnitudes fainter in I than the lowest luminosity L dwarf currently known, while the absolute magnitude we deduce at J is almost identical with M_J for Gl 229B. Theoretical models indicate a mass ratio of \~0.75. The mean separation of the L dwarf binaries in the current sample is smaller by a factor of two than amongst M dwarfs. We discuss the implications of these results for the temperature scale in the L/T transition region and for the binary frequency amongst L dwarfs.Comment: 38 pages, 11 figures; accepted for A

Perbandingan Prestasi Mahasiswa Berdasar Seleksi Masuk UIN, melalui PPA, Tes Tulis Lokal, dan SPMB: Studi pada Program Studi Fakultas Sains dan Teknik Informatika Fakultas Sains dan Tekniknologi UIN SGD Bandung Angkatan Tahun 2007

Diketahui, bahwa perbandingan hasil belajar mahasiswa menjadi persoalan manakala raw input mahasiswa menunjukkan gejala yang berbeda. Mahasiswa dengan jalur tes yang manakah yang dianggap paling berpretasi? Bagaimana pengelolaan dan manajemen pembelajaran yang efektif jika terdapat perbedaan prestasi belajar yang signifikan?. Penelitian ini, menggunakan metode deskriptif, yang menggambarkan keadaan dan gejala sesuai dengan apa adanya tanpa adanya perlakuan yang khusus, bahwa penelitian deskriptif merupakan penelitian yang dimaksudkan untuk mengumpulkan informasi mengenai status suatu gejala yang ada, yaitu keadaan gejala menurut apa adanya pada saat penelitian dilakukan. Beradasarkan analisis penelitian ini, menunjukkan bahwa: (1) Prestasi belajar mahasiswa Program Studi Informatika angkatan tahun 2007 pada kelompok mata kuliah Ilmu Agama Islam (Al-Qur’an/Ilmu Tafsir, Hadits Ilmu Hadits, Fiqh/Ushul Fiqh) antara mahasiswa yang diterima melalui jalur SPMB, PPA dengan yang diterima melalui Ujian Tulis Lokal tidak ada perbedaan yang signifikan; (2) Prestasi belajar mahasiswa Program Studi Informatika angkatan tahun 2007 pada kelompok mata kuliah Bahasa (Bahasa Indonesia, Bahasa Inggris, Bahasa Arab, dan English Communication Skill) antara mahasiswa yang diterima melalui jalur SPMB, PPA dengan yang diterima melalui Ujian Tulis Lokal berbeda secara signifikan; (3) Prestasi belajar mahasiswa Program Studi Informatika angkatan tahun 2007 pada kelompok mata kuliah Komponen Fakultas (Kimia Dasar, Fisika Dasar, Kalkulus, dan Pengetahuan Lingkungan) antara mahasiswa yang diterima melalui jalur SPMB, PPA dengan yang diterima melalui jalur Ujian Tulis Lokal bebeda secara aignifikan; (4) Prestasi belajar mahasiswa Program Studi Informatika angkatan tahun 2007 pada kelompok kuliah mata kuliah keahlian (Pengantar Teknologi Informasi, Algoritma dan Pemrograman, Aljabar Linier, Komputer dan Masyarakat) antara mahasiswa yang diterima melalui jalur SPMB, PPA dengan yang diterima melalui Ujian Tulis Lokal berbeda secara signifikan; (5) Indeks Prestasi mahasiswa semester I dan II Program Studi Informatika angkatan tahun 2007 antara mahasiswa yang diterima melalui jalur SPMB, PPA dengan yang diterima melalui Ujian Tulis Lokal berbeda secara signifikan. Penelitian ini, menyimpulkan bahwa mahasiswa yang diterima melalui SPMB mempunyai prestasi lebih tinggi dibandingkan dengan mahasiswa yang diterima melalui PPA dan ujian lokal, karena mereka merupakan siswa-siswa berprestasi di sekolahnya dan mengikuti seleksi lebih kompetitif

Candidate Disk Wide Binaries in the Sloan Digital Sky Survey

Using SDSS Data Release 6, we construct two independent samples of candidate stellar wide binaries selected as i) pairs of unresolved sources with angular separation in the range 3'' - 16'', ii) common proper motion pairs with 5'' - 30'' angular separation, and make them publicly available. These samples are dominated by disk stars, and we use them to constrain the shape of the main-sequence photometric parallax relation M_r(r-i) and to study the properties of wide binary systems. We estimate M_r(r-i) by searching for a relation that minimizes the difference between distance moduli of primary and secondary components of wide binary candidates. We model M_r(r-i) by a fourth degree polynomial and determine the coefficients using Markov Chain Monte Carlo fitting, independently for each sample. Aided by the derived photometric parallax relation, we construct a series of high-quality catalogs of candidate main-sequence binary stars. Using these catalogs, we study the distribution of semi-major axes of wide binaries, a, in the 2,000 < a < 47,000 AU range. We find the observations to be well described by the Opik distribution, f(a)~1/a, for a<a_{break}, where a_{break} increases roughly linearly with the height Z above the Galactic plane (a_{break}~12,300 Z[kpc]^0.7 AU). The number of wide binary systems with 100 AU < a < a_{break}, as a fraction of the total number of stars, decreases from 0.9% at Z=0.5 kpc to 0.5% at Z=3 kpc. The probability for a star to be in a wide binary system is independent of its color. Given this color, the companions of red components seem to be drawn randomly from the stellar luminosity function, while blue components have a larger blue-to-red companion ratio than expected from luminosity function.Comment: emulateApJ, 47 pages, 28 figures, accepted to Ap

Stellar mass map and dark matter distribution in M31

Stellar mass distribution in M31 is estimated using optical and infrared imaging data. Combining the derived stellar mass model with various kinematical data, properties of the DM halo of the galaxy are constrained. SDSS observations through the ugriz filters and the Spitzer imaging at 3.6 microns are used to sample the SED of the galaxy at each imaging pixel. Intrinsic dust extinction effects are taken into account by using far-infrared observations. Synthetic SEDs created with different stellar population synthesis models are fitted to the observed SEDs, providing estimates for the stellar mass surface density. The stellar mass distribution of the galaxy is described with a 3D model consisting of a nucleus, a bulge, a disc, a young disc and a halo component, each following the Einasto density distribution (relations between different functional forms of the Einasto density distribution are given in App. B). By comparing the stellar mass distribution to the observed rotation curve and kinematics of outer globular clusters and satellite galaxies, the DM halo parameters are estimated. Stellar population synthesis models suggest that M31 is dominated by old stars throughout the galaxy. The total stellar mass is (10-15)10^10Msun, 30% of which is in the bulge and 56% in the disc. None of the tested DM distribution models can be falsified on the basis of the stellar matter distribution and the rotation curve of the galaxy. The virial mass of the DM halo is (0.8-1.1)10^12Msun and the virial radius is 189-213kpc, depending on the DM distribution. The central density of the DM halo is comparable to that of nearby dwarf galaxies, low-surface-brightness galaxies and distant massive disc galaxies, thus the evolution of central DM halo properties seems to be regulated by similar processes for a broad range of halo masses, environments, and cosmological epochs.Comment: 11 pages, 13 figures, 6 tables, accepted for publication in Astronomy and Astrophysic

Can Planets survive Stellar Evolution?

We study the survival of gas planets around stars with masses in the range 1-5 Msun, as these stars evolve off the Main Sequence. We show that planets with masses smaller than one Jupiter mass do not survive the Planetary Nebula phase if located initially at orbital distances smaller than (3-5) AU. Planets more massive than two Jupiter masses around low mass (1 Msun on the Main Sequence) stars survive the Planetary Nebula stage down to orbital distances of 3 AU. As the star evolves through the Planetary Nebula phase, an evaporation outflow will be established at the planet's surface. Evaporating planets may be detected using spectroscopic observations. Planets around white dwarfs with masses M_WD > 0.7 Msun are generally expected to be found at orbital radii r > 15 AU. If planets are found at smaller orbital radii around massive white dwarfs, they had to form as the result of the merger of two white dwarfs.Comment: 30 pages, 7 figures, 2 tables, accepted for publication in Ap