On the Rotation of the Stars

Shajn, G.; Struve, Otto

doi:10.1093/mnras/89.3.222

Cited by 81 publications

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“…The early model of Shajn & Struve (1929), (i.e. the CMRS) considered the Doppler broadening of an arbitrarily sharp spectral line, having finite equivalent width, by the Doppler motion of a rotating spherical star with its axis inclined at an angle i to the line of sight.…”

Section: The Determination and Interpretationmentioning

confidence: 99%

“…Although Shajn & Struve's (1929) graphical approach employed a uniformly bright star, Carroll (1933) extended it to included limb-darkening. Carroll (1933) did realize that limb-darkening would affect the resultant line shape by reducing the contribution from the stellar limb where the greatest projected rotational velocities are found.…”

Section: The Determination and Interpretationmentioning

confidence: 99%

“…When combined with the Shajn & Struve (1929) graphical approach some sort of 'convolution' of a Doppler profile with the intrinsic profile results. Slettebak's inclusion of gravity-darkening first described by von Zeipel (1924a,b) as well as limb-darkening resulted in a first-approximation improvement over the classical model that was widely used for the determination of v sin i.…”

Section: The Determination and Interpretationmentioning

confidence: 99%

“…In this day of relatively convenient numerical computation, it is easy to criticize the simple model of Shajn & Struve (1929) as being unreasonably simplistic and ignore the extremely clever graphical technique that allows such a model to yield an analytical result for a line profile of an intrinsically sharp line in terms of a single parameter vesini (see Collins 1989 for derivation). While Carroll, Struve and others realized that atmospheric limb-darkening and von Zeipel's (1924a,b) arguments concerning "gravity-darkening" would result in the simple interpretation yielding only a lower limit on the equatorial speed where V e sin i itself only yields an upper limit, the model could be regarded as an excellent first step for investigating stellar rotation.…”

Section: Stellar Models For the Determination Of V Sin Imentioning

confidence: 99%

“…It was almost immediately confirmed by, Rossiter's doctoral advisor, McLaughlin (1924) in Algol. It seems likely that Rossiter's (1924) explanation was a major impetus for the subsequent development of rotating stellar models.In spite of the elegant formulation by Caroll (1928Caroll ( , 1933, it was the simple graphical presentation of the model by Shajn & Struve (1929), shown at the right of Figure 1, that laid the foundation for much of the work done in the 20th century. This classical model led to the term v sin i for it had a very specific meaning within its context and as Collins & Truax (1995) point out should probably be denoted V e sin i.…”

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The Determination and Interpretation of the Rotation Parameter v sin i

Collins

2004

Symp. - Int. Astron. Union

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Abstract. In this paper we review the development of the concept of the stellar rotation parameter commonly known as v sin i. We emphasize that the interpretation of the parameter in terms of physical characteristics of the star always depends on comparison with a model that is intended to represent the physical properties of the star. To that end we will trace the development of such models along with the observational means of determining the parameter. Emphasis will be place on the traditional methods involving stellar spectroscopy, but some attention will be place on indirect methods involving direct measurement of the rotation period and recent interferometric determination of stellar oblatness. In addition we will comment on recent techniques involving the simultaneous measurement of many spectral lines and synthetic spectra to improve the accuracy of rotational half-widths.The natural desire for simplicity of such models has often resulted in erroneous values for stellar parameters. This is particularly the case for the most rapidly rotating stars generally of early spectral type, but may also be present in some giants and supergiants where rapid rotation is difficult to detect. Finally, we will comment on the possibilities of improving the quality of both the measurement and interpretation of this important stellar rotation parameter. IntroductionEver since Galileo proclaimed, in the Sidereal Messenger (1610), that some celestial objects both rotated and revolved those who observe the heavens have enquired into the rotation of stars. Thomas Wright (1750) noted that stars were like the sun and vice verse and, by noting that the sun rotated on its axis, he may be credited with being the first to speculate that stars do so as well. But the actual observation of such phenomenon had to wait until stellar spectroscopy improved sufficiently to quantitatively observe the shape of stellar spectra lines. While Otto Struve is generally credited with being the "father of stellar rotation", seminal work by a number of astronomers early in the 20th century laid a broad foundation for the quantitative determination of stellar rotation. Although Shapley & Nicholsen (1919) were the first to formalize the concept of rotational broadening, Carroll (1928Carroll ( , 1933 and Carroll & Ingram (1933) developed the first workable model and applied it to stellar systems. Collins & Truax (1995) Rossiter's (1924) explanation of an anomaly in the radial velocity curve (3 Lyrae as resulting from the axial rotation of the eclipsed star during the eclipse. The systematic covering of the eclipsed disk yields shifts in the center of spectral lines during the eclipse resulting from apparent changes in the mean line-of-sight motion of the rotating eclipsed star. This effect, which is yet to be described for any star by an ab initio model, is still generally known as the Rossiter Effect and is considered to be first direct confirmation that stars do rotate. It was almost immediately confirmed by, Rossiter's doctoral advisor, McLaughlin (1...

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Section: The Determination and Interpretationmentioning

confidence: 99%

Section: The Determination and Interpretationmentioning

confidence: 99%

Section: The Determination and Interpretationmentioning

confidence: 99%

Section: Stellar Models For the Determination Of V Sin Imentioning

confidence: 99%

mentioning

confidence: 99%

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The Determination and Interpretation of the Rotation Parameter v sin i

Collins

2004

Symp. - Int. Astron. Union

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Die Hypothese des Energiegleichgewichtes in der Bahn für enge Doppelsternsysteme

Walter

1955

Astron Nachr

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Es wird versucht, die Zusammenhange zwischen den Bahnformen der engen Doppelsternsysteme und den Rotationseigenschaften ihrer Komponenten durch eine Hypothese zu erfassen, i n der die Einfliisse der differentiellen Rotation und der Gezeitenschwingungen der Komponenten auf die Bahn beriicksichtigt werden. Die Gleichungen werden aufgestellt , welche die Bahnformen und die differentielle Rotation der Komponenten bestimmen, undes wird das Verhalten der Systeme bei verschiedenen Distanzen der Komponenten untersucht. Mit den Beobachtungen ergibt sich gute Ubereinstimmung, wenn fur die Hauptreihensteme die Existenz rotationsaufspaltender Krafte angenommen wird. Die Hypothese scheint auch einen Beitrag zum Problem der Gasstrtjme liefern zu ktinnen. Differentielle Rotation von Doppelsternkomponenten im Fall von KreisbahnenEs werde vorausgesetzt, daB die Komponenten von Doppelsternen aus Griinden, denen hier nicht weiter nachgegangen werden soll, bestrebt sind, in ihrem Innern eine ungleichformige Rotation hervorzurufen. ahnlich derjenigen, welche bei der Sonne durch die bekannten Unterschiede der Winkelgeschwindigkeiten in verschiedenen heliographischen Breiten angezeigt wird.Sind Rotationsunterschiede im Sterninnern ausgebildet, so wirkt bei Doppelsternkomponenten wie bei Einzelsternen die Reibung zwischen verschieden rasch rotierenden Schichten in Richtung eines Abbaus der Geschwindigkeitsunterschiede. Streng genommen muate man hier beriicksichtigen, daB die Schichten gleicher Rotation infolge der Gezeitendeformation der Doppelsternkomponenten bei diesen etwas anders verlaufen als beim rotationssymmetrischen Einzelstern. Der aus diesem Grunde hervorgerufene Unterschied der Reibungskrafte diirfte jedoch von untergeordneter Bedeutung sein. Er werde deshalb hier vernachlassigt.Die Abweichung der Schichten einer gezeitendeformierten Doppelsternkomponente von der Rotationssymmetrie wirkt sich aber dann wesentlich aus, lwenn die Rotationsgeschwindigkeit von der Winkelgeschwindigkeit der Umlaufsbewegung der Komponenten in der Bahn abweicht . In diesem Fall bildet sich eine Gezeitenwelle aus, die mit gleichmaoiger Geschwindigkeit in der Schicht so umlauft, daB standig der eine Flutberg in der Richtung zum andern Stern steht. Die Gezeitenwelle verursacht Massenverschiebungen, die nicht ohne Reibungswiderstande verlaufen. Wir denken uns nun die gezeitendeformierte Doppelsternkomponente in verschieden rasch rotierende Teilkorper a (a = I, 2 . . .) aufgeteilt. Die Richtung 1 zeige zum Schwerpunkt der Bahn, wahrend ya mit der Materie der einzelnen Teilkorper verbunden gedachte, beliebig gewahlte Meridianrichtungen seien. Wir betrachten nun einen Teilkorper a, dessen Rotationsgeschwindigkeit wa = dya/dt von der Winkelgeschwindigkeit der Bahnbewegungp =dl/dt abweicht. Tn diesem Fall muI3 die Materie des Teilkorpers bei ihrer Rotation abwechselnd grol3ere und kleinere Querschnitte durchlaufen. Auf den Teilkorper a wird dadurch ein Widerstand ausgeiibt, der offensichtlich mit dem Unterschied zwischen dem groBten und dem kleinsten Quers...

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Comparisons between Doppler Imaging and starspot modelling

Budding

Zeilik

Surface Inhomogeneities on Late-Type Stars

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On the Rotation of the Stars

Cited by 81 publications

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The Determination and Interpretation of the Rotation Parameter v sin i

The Determination and Interpretation of the Rotation Parameter v sin i

Die Hypothese des Energiegleichgewichtes in der Bahn für enge Doppelsternsysteme

Comparisons between Doppler Imaging and starspot modelling

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