Planetesimals to brown dwarfs: What is a planet?

The past 15 years have brought about a revolution in our understanding of our Solar System and other planetary systems. During this time, discoveries include the first Kuiper belt objects (KBOs), the first brown dwarfs, and the first extrasolar planets. Although discoveries continue apace, they have called into question our previous perspectives on planets, both here and elsewhere. The result has been a debate about the meaning of the word "planet" itself. It is clear that scientists do not have a widely accepted or clear definition of what a planet is, and both scientists and the public are confused (and sometimes annoyed) by its use in various contexts. Because "planet" is a very widely used term, it seems worth the attempt to resolve this problem. In this essay, we try to cover all the issues that have come to the fore and bring clarity (if not resolution) to the debate

Profiles of Strong Permitted Lines in Classical T Tauri Stars

We present a spectral analysis of 30 T Tauri stars observed with the Hamilton echelle spectrograph over more than a decade. One goal is to test magnetospheric accretion model predictions. Observational evidence previously published supporting the model, such as emission line asymmetry and a high frequency of redshifted absorption components, are considered. We also discuss the relation between different line forming regions and search for good accretion rate indicators. In this work we confirm several important points of the models, such as the correlation between accretion and outflow, broad emission components that are mostly central or slightly blueshifted and only the occasional presence of redshifted absorption. We also show, however, that the broad emission components supposedly formed in the magnetospheric accretion flow only partially support the models. Unlike the predictions, they are sometimes redshifted, and are mostly found to be symmetric. The published theoretical profiles do not have a strong resemblance to our observed ones. We emphasize the need for accretion models to include a strong turbulent component before their profiles will match the observations. The effects of rotation, and the outflow components, will also be needed to complete the picture.Comment: 25 pages including 9 figures, 3 tables, accepted for publication in the Astronomical Journa

Pengaruh Penggunaan Facebook Terhadap Interaksi Sosial Remaja Di SMKN Pertanian Terpadu Provinsi Riau

Facebook is very influential on adolescent social interaction seen from a high level of adolescent motivation in using this facebook. The research aims to determine the effect of using facebook to adolescent social interaction in the play facebook. Metode study is correlational nature with quantitative approach that compares motivation teenagers using facebook and social interactions play facebook. Sampel used in this study is the Integrated Agricultural SMKN Riau Province consists of 100 class X and class XI 79 Random selected Sampling. The results of analysis data can be concluded that the use of facebook influence on adolescent social interaction with significant value Sig.0.001 of <0.05 and views of the value of the average score Motivation teenagers using facebook as much as 67 respondents with a percentage of 37.4% and the Social Interaction 39 respondents with a percentage of 21.8% .With thus seen a significant difference between the use of facebook with Social Interaction teens in play facebook.Keywords: Facebook, Social Interaction, teenager

The pre-main sequence spectroscopic binary UZ Tau East: improved orbital parameters and accretion phase dependence

We present radial-velocity measurements obtained using high- and intermediate-resolution spectroscopic observations of the classical T Tauri star UZ Tau East obtained from 1994 to 1996. We also provide measurements of H$\alpha$ equivalent widths and optical veiling. Combining our radial-velocity data with those recently reported by Prato et al. (2002), we improve the orbital elements for this spectroscopic binary. The orbital period is 18.979$\pm$0.007 days and the eccentricity is e=0.14. We find variability in the H$_\alpha$ emission and veiling, signposts of accretion, but at periastron passage the accretion is not as clearly enhanced as in the case of the binary DQ Tau. The difference in the behaviour of these two binaries is consistent with the hydrodynamical models of accretion from circumbinary disks because UZ Tau East has lower eccentricity than DQ Tau. It seems that enhanced periastron accretion may occur only in systems with very high eccentricity (e$>$0.5).Comment: accepted for publication in A&

Uji Coba Mesin Pengering Kayu Kombinasi Tenaga Surya Dan Panas Dari Tungku Tipe I

Telah dilakukan uji coba teknis dan finansial terhadap mesin pengeringan kayu kombinasi tenaga surya dan panas dari tungku tipe SC+TI untuk kapasitas 19 m3 di salah satu industri/pengrajin kayu di Ngaringan, Grobogan, Jawa Tengah. Uji coba dilakukan terhadap kayu jati (Tectona grandis L.f.). Kebutuhan panas pengeringan di siang hari diperoleh dari tenaga surya dan di malam hari atau tergantung kebutuhan diperoleh dari tungku pembakaran dengan bahan bakar biomas/limbah kayu dari penggergajian sendiri. Tujuan uji coba adalah untuk mengetahui kelayakan teknis dan finansial dari pemanfaatan masin pengering tersebut.Hasil uji coba menunjukan suhu rata-rata harian dari panas surya yang diterima ruang pengering berkisar antara 40 - 50°C, sementara suhu untuk pengeringan kayu jati berkisar antara 45 - 70°C. Kekurangan panas diperoleh dari tungku bakar. Untuk mengeringkan sortimen kayu dengan kadar air 50% sampai mencapai kadar air 10% memerlukan waktu rata-rata 13 hari dan menghasilkan rendemen kayu kering sekitar 80%. Konsumsi limbah kayu untuk bahan bakar tungku pada setiap periode pengeringan 8 m3.Investasi pendirian unit pengeringan memerlukan biaya sebesar Rp 74.635.000. Biaya produksi setahun (jumlah produksi 304 m3) adalah Rp 3.251.548.750, sehingga harga pokok produk Rp 10.695.884/m3. Analisis kelayakan finansial pemanfaatan mesin pengering menunjukan dengan harga jual kayu jati kering Rp 11.000.000/m3. Titik impas (BEP) tercapai pada produksi sebesar 86,3 m3, Nilai sekarang neto (NPV) Rp + 374.245.458 dan Internal Rate of Return (IRR) 80%. Hasil ini menunjukkan bahwa mesin pengering tersebut layak untuk dioperasikan

High resolution absolute flux profiles of the MC 2 h and k lines in evolved F8 to M5 stars

The central results of a survey of the Mg II resonance line emission in a sample of over 50 evolved late type stars, including spectral-luminosity type F8 to M5 and La to IV are presented. Observed and surface fluxes are derived and correlations noted. The major findings include: (1) Mg II k emission core asymmetry transition near K1 III, analogous to that known for Ca II K; (2) a small gravity and temperature dependence of the Mg II chromospheric radiative loss rate

Impregnasi Ekstrak Jati Dan Resin Pada Kayu Jati Cepat Tumbuh Dan Karet

Penelitian sebelumnya menunjukkan karakteristik fisis, mekanis dan keawetan kayu jati cepat tumbuh (JCT) relatif lebih rendah dibanding kayu jati tradisional. Berdasarkan hal tersebut, perlakuan modifikasi kayu dapat dilakukan dengan perlakuan tertentu untuk meningkatkan kualitas kayunya. Penelitian ini bertujuan menyempurnakan karakteristik kayu JCT dan karet dengan perlakuan impregnasi ekstrak jati dan resin hingga mendekati atau setara dengan karakteristik kayu jati tradisional. Dalam penelitian ini dilakukan ekstraksi serbuk kayu jati tradisional dengan pelarut metanol. Larutan ekstrak tersebut kemudian diimpregnasi ke dalam struktur kayu JCT dan karet dengan beragam konsentrasi menurut penambahan resin organik. Resin yang digunakan sebagai campuran dalam penelitian ini adalah sirlak dan damar, masing-masing dengan konsentrasi berat 4, 6 dan 8% dari volume ekstrak. Hasil penelitian menunjukkan perlakuan impregnasi larutan ekstrak jati terhadap kayu JCT dan karet mampu meningkatkan stabilitas dimensi kedua jenis kayu tersebut dengan nilai ASE lebih dari 50%, hingga setara dengan stabilitas jati tradisional. Penambahan resin sirlak maupun damar ke dalam larutan ekstrak jati secara nyata dapat lebih menyempurnakan sifat stabilitas dimensi kayu JCT dan karet secara proporsional menurut konsentrasi resin