scholarly journals Disks and Toroids Around Young Stars

1987 ◽  
Vol 115 ◽  
pp. 239-253 ◽  
Author(s):  
L.F. Rodríguez

We review the observational evidence for interstellar and circumstellar size gaseous structures that appear to be collimating the bipolar outflows observed in regions of star formation. In particular, there is growing evidence for circumstellar disk-like objects that may be related to a protoplanetary cloud like the one that once surrounded the Sun. There are similarities between these disks around young stars and that found around the main sequence star β Pictoris. Both flattened structures around L1551 IRS5 and β Pictoris appear to have an inner “hole” with radius of a few tens of AU. On the other hand, there is observational support for focusing and collimation processes acting on the same source from tens of AU (circumstellar dimensions) to tenths of pc (interstellar dimensions).

JOGED ◽  
2017 ◽  
Vol 7 (2) ◽  
Author(s):  
Dewi Sinta Fajawati

Bulan merupakan sumber inspiratif dalam penggarapan karya tari ini. Secara ilmu pengetahuan, Bulan adalah benda langit yang disebut satelit, satelit satu-satunya yang dimiliki Bumi dan tercipta secara alami. Banyak teori yang mengatakan tentang terbentuknya Bulan, salah satunya adalah teori Big bang atau dentuman besar. Pada dasarnya Bulan hanyalah sebuah Benda besar berbentuk bulat yang tidak bisa bercahaya, cahaya yang kita lihat pada malam hari merupakan refleksi dari cahaya matahari. Akan tetapi keindahannya memang tidak bisa dipungkiri, karena dia paling bercahaya diantara hamparan langit yang gelap. Cahayanya tidak selalu terang, bahkan tidak selalu bulat, terkadang hanya terlihat setengah atau terlihat seperti sabit..            Penata tari memetaforakan objek bulan yang berada di tempat yang sangat tinggi sebagai sebuah cita-cita yang ingin dicapai. Seringkali lagu anak-anak yang menjadi pengalaman auditif penata tari, menjadikan bulan sebagai objek yang ingin digapai, misal lagu ‘Ambilkan Bulan Bu’. Namun intisari yang akan dipakai dalam penggarapan koregrafinya adalah tentang fase bulan yang tercipta. Bersumber dari rangsang awal melihat bulan atau rangsang visual, penata tari menginterpretasikan fase-fase bulan yang terjadi sebagai fase kehidupan yang dijalani untuk menggapai sebuah cita-cita tersebut.            Koreografi diwujudkan dalam bentuk kelompok dengan membagi dua karate penari. Delapan penari merupakan simbolisasi Bulan, dan satu penari sebagai manusia yang bercita-cita. Dengan bentuk tari dramatik, penyajiannya dibagi menjadi 5 adegan, yaitu Introduksi Big bang, Adegan 1 Moon happen, Adegan 2 Mengejar Impian, Adegan 3 Dancing with Moon, dan Ending ‘Catch Your Dream’. The moon is the essential inspirations of this choreograph. Theoretically, the moon is a sky object which is called as satellite. The one and only naturally created satellite belongs to the planet Earth. There are many theories that explain how the moon was created. One of those theories is Big Bang theory or massive crash. Basically, the moon is just a huge circle thing which is unable to shine its glow. The light that we experience in the evening is the reflection of the sun. However, thebeauty of the moonlight is undeniable as it has the significant light within the darkest night sky. Its light is not always the strongest, even it’s not always circle (full), every so often it is seemed only the half part of it or crescent moon.            The choreographer interpreted the moon that belongs in the highest as the goals that she wants to reach. Most of the time, the children songs (lullaby) that pick the moon as the main object that is desired to be reached, for example the song “Ambilkan Bulan, Bu”. The essential idea that is explored in this choreograph is the creational phase of the moon itself. It was started by way of visual reaction when the choreographer observed the moon, she interpret the moon’s phases as the phases in human’s life which are gone through to reaching their goals. Fall and recovery, passionate, and even sometimes they give it in, are interpreted from the moonlight. The full moon which has the brightest and the most perfect light is likened as the strong spirit. The crescent moon with its soft light is interpreted as low spirit and unconfident.             This in-group-choreograph is separated into two characters with 8 female dancers that are the symbolization of the moon and the other one female dancer symbolizes a human with aspire. With dramatic dance form, this choreograph is presented into five parts, including introduction part of Big Bang, Moon Happen in part one, Chasing Dream is part two, Dancing With The Moon in part three, Catch Your Dream in the ending part.


1989 ◽  
Vol 107 ◽  
pp. 376-376
Author(s):  
K. D. Abhyankar ◽  
M. L. Vyas

Complete UBV light-curves of RR-Lep and RX-Hya have been obtained during 1983-87 seasons. Preliminary elements were computed using modified Wellmann’s method. With these parameters as inputs Wilson-Devinney program was executed for Blue and Yellow passbands simultaneously in detached and semi-detached modes for both the systems. The semidetached mode fitted better than the other solution for both the systems. For RR-Lep, the absolute dimensions were computed by assuming the primary to be a slightly evolved main sequence star. For RX-Hya, the absolute dimensions were computed using Struve’s spectroscopic data. The following table gives all the elements for both the systems. The secondaries of both the systems are overluminous for their masses suggesting that they have lost considerable mass.


1993 ◽  
Vol 137 ◽  
pp. 755-757
Author(s):  
P. Lemaire

AbstractProbing the interior of the Sun, a slow rotator G2 V main sequence star, and connecting the atmospheric structure to inside phenomena is one of the objectives of the SOHO mission. An overview of the helioseismology and of the coronal instruments is given. It furnishes a guide line for missions that are dedicated to the probing of stellar interiors in using microvariability and activity as tracers, such as the PRISMA study.


1957 ◽  
Vol 35 (6) ◽  
pp. 766-776 ◽  
Author(s):  
Luise Herzberg

The wavelength displacements between the solar limb and the center of the disk, (λL–λc), have been measured for six infrared solar lines, belonging to two multiplets of Sil. The displacements of the lines of one of the multiplets are the same, within the accuracy of the measurements; the displacements of the lines of the other multiplet, although varying somewhat amongst themselves, are systematically larger. This grouping of the results according to multiplet structure suggests that the wavelength displacement of solar lines across the disk is term-dependent. It is noted that the variation of the values (λL–λC) is, in its essential features, similar to the term-dependent variation of the differences [Formula: see text] between the published solar and laboratory wavelengths of silicon. Solar and laboratory data, taken together, appear to provide observational evidence that the observed wavelength variations across the solar disk are, at least in part, due to collision or field effects.


1980 ◽  
Vol 85 ◽  
pp. 129-133
Author(s):  
J.-C. Mermilliod

The present state of astrometric, spectroscopic and photometric data for stars in 63 open clusters nearer to the Sun than 750 pc is summarized. Table I reports the limits of the available data in terms of the apparent V magnitude, in the same way as the previous version (Mermilliod 1977). Information on the apparent V magnitude of the brightest main sequence star (Vbr) and on the number of stars brighter than V=10 (n∗) has been included. In addition, the bluest spectral type on the main sequence has been used as an age estimator (TS).


2018 ◽  
Vol 10 (2) ◽  
pp. 285-305
Author(s):  
George A. Gazis

Abstract This article identifies the influence of the Homeric ‘Poetics of Hades’ in Greek Lyric and argues for an aetiological relationship between the persistent presentation of the lyric poet’s subjective voice and the freedom of speech introduced in Homer’s Underworld. The article demonstrates this relationship through an examination of Bacchylides’ Ode 5 and argues that the lyric poet consciously innovates upon Homer’s underworld narratives by allowing his Meleager to occupy the stage and takes the audience through his agonising last minutes by describing what dying feels like in his own voice. In doing so, Bacchylides presents his audeience with a Meleager who glosses over his heroic actions and moments of glory in favour for a more emotional and subjective view of his past, filled with regret and self-pity. In this respect the hero is no different from the ghost of Achilles who dismisses honour after death for the simple privilege of seeing the light of the sun, or Agamemnon who is consumed by the memory of his wife’s treachery while having nothing to say about his glorious exploits at Troy. This powerful retelling of the story of a great epic hero of the past looks, I argue, simultaneously backwards and forwards, since on the one hand it is inherited from Homer’s ‘Poetics of Hades’, while on the other, it anticipates the emotional and unmediated voices of the heroes and heroines of the tragic stage.


1968 ◽  
Vol 88 ◽  
pp. 114-127 ◽  
Author(s):  
D. O'Brien

In a study earlier in this volume, ‘The Relation of Anaxagoras and Empedocles’, pp. 93–113, I listed the ancient evidence to the effect that Anaxagoras first gave the correct explanation of an eclipse, and that he was followed in this by Empedocles. A more extensive examination of the evidence raises certain difficulties. For what are, or might appear to be, Anaxagoras' theories are attributed elsewhere to earlier thinkers.There are two principal elements in this contradiction, the one direct and the other indirect.1. There is a direct contradiction when Thales, Anaximenes and some Pythagoreans are said to have given the correct explanation of an eclipse, at least if we suppose the Pythagoreans in question to have been earlier than Anaxagoras.2. There has been thought to be an indirect contradiction when several thinkers before Anaxagoras are said to have derived the moon's light from the sun. For a theory of derived light for the moon has been thought, whether rightly or wrongly, to entail the correct explanation of an eclipse.In what follows I shall attempt to solve these, and some other incidental difficulties.


2009 ◽  
Vol 5 (S268) ◽  
pp. 375-380 ◽  
Author(s):  
M. H. Pinsonneault

AbstractI review basic observational features in Population I stars which strongly implicate rotation as a mixing agent; these include dispersion at fixed temperature in coeval populations and main sequence lithium depletion for a range of masses at a rate which decays with time. New developments related to the possible suppression of mixing at late ages, close binary mergers and their lithium signature, and an alternate origin for dispersion in young cool stars tied to radius anomalies observed in active young stars are discussed. I highlight uncertainties in models of Population II lithium depletion and dispersion related to the treatment of angular momentum loss. Finally, the origins of rotation are tied to conditions in the pre-main sequence, and there is thus some evidence that environment and planet formation could impact stellar rotational properties. This may be related to recent observational evidence for cluster to cluster variations in lithium depletion and a connection between the presence of planets and stellar lithium depletion.


PMLA ◽  
1972 ◽  
Vol 87 (3) ◽  
pp. 499-507
Author(s):  
Jean-Pierre Barricelli

Manzoni structured his novel like a tapestry with juxtaposing planes or masses symbolizing good and evil and the redemptive tragedy that inevitably ensues when these forces meet. Thus a symmetrical expressive structure is simultaneously a moral structure. The tapestry is further crosswoven with images that interrelate and deepen the meaning of the context in which they appear or of the character with whom they are associated. They become word-symbols: words like “wall” or “skull” set tonalities, and so does “bread” as opposed to “wine” or “devil.” Similarly, descriptions involving images of light or the sun weave a dialectical fabric with images of darkness or clouds. While on the one hand the symbols exteriorize situations and events, on the other they are interiorized into the narrative and its characters so as to become their very lifeblood. What has been called Manzoni's “lyricization” of reality stems directly from this process.


2017 ◽  
Vol 7 (2) ◽  
pp. 238
Author(s):  
Shadi Saleh Neimneh

This article looks into the postcolonial Arabic narrative of Ghassan Kanafani to examine its underplayed existential and naturalistic aspects. Postcolonial texts (and their exegeses) deal with the effects of colonization/imperialism. They are expected to be political and are judged accordingly. Drawing on Kanafani’s Men in the Sun (1963), I argue that the intersection among existentialism and naturalism, on the one hand, and postcolonialism, on the other, intensifies the political relevance of the latter theory and better establishes the politically committed nature of Kanafani’s fiction of resistance. In the novella, the sun and the desert are a pivotal existential symbol juxtaposed against the despicable life led by three Palestinian refugees. The gruesome death we encounter testifies to the absurdity of life after attempts at self-definition through making choices. The gritty existence characteristic of Kanafani's work makes his representation of the lives of alienated characters more accurate and more visceral. Kanafani uses philosophical and sociological theories to augment the political nature of his protest fiction, one acting within postcolonial parameters of dispossession to object to different forms of imperialism and diaspora. Therefore, this article explores how global critical frameworks (naturalism and existentialism) enrich the localized contexts essential to any study of postcolonial literature and equally move the traditional national allegory of Kanafani to a more realist/unidealistic level of political indictment against oppression. 


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