Stability and Radial Vibration Periods of the Hamada–Salpeter White Dwarf Models

Faulkner, John; Gribbin, John

doi:10.1038/218734a0

Cited by 34 publications

(8 citation statements)

References 14 publications

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“…In fact, in the abstract of his paper, Landolt just announced: "Photoelectric data which point to a 12 m .5 variation in the brightness of a white-dwarflike star are discussed". The luminosity variations detected in HL Tau 76, with a period of about 740 s, were too long to be attributed to radial modes, according to the theoretical studies available at that time (Faulkner & Gribbin 1968;Ostriker & Tassoul 1968). Two other variable white dwarfs were discovered in the meantime by Lasker & Hesser (1969): G 44−32 (with periods in the range 600−800 s) and R 548 (with periods in the range 200−300 s).…”

Section: Brief History Of Discoverymentioning

confidence: 99%

Evolutionary and pulsational properties of white dwarf stars

Althaus

Córsico

Isern

et al. 2010

Astron Astrophys Rev

380

372

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White dwarf stars are the final evolutionary stage of the vast majority of stars, including our Sun. Since the coolest white dwarfs are very old objects, the present population of white dwarfs contains a wealth of information on the evolution of stars from birth to death, and on the star formation rate throughout the history of our Galaxy. Thus, the study of white dwarfs has potential applications to different fields of astrophysics. In particular, white dwarfs can be used as independent reliable cosmic clocks, and can also provide valuable information about the fundamental parameters of a wide variety of stellar populations, like our Galaxy and open and globular clusters. In addition, the high densities and temperatures characterizing white dwarfs allow to use these stars as cosmic laboratories for studying physical processes under extreme conditions that cannot be achieved in terrestrial laboratories. Last but not least, since many white dwarf stars undergo pulsational instabilities, the study of their properties constitutes a powerful tool for applications beyond stellar astrophysics. In particular, white dwarfs can be used to constrain fundamental properties of elementary particles such as axions and neutrinos, and to study problems related to the variation of fundamental constants.These potential applications of white dwarfs have led to a renewed interest in the calculation of very detailed evolutionary and pulsational models for these stars. In this work, we review the essentials of the physics of white dwarf stars. We enumerate the reasons that make these stars excellent chronometers and we describe why white dwarfs provide tools for a wide variety of applications. Special emphasis is placed on the physical processes that lead to the formation of white dwarfs as well as on the different energy sources and processes responsible for chemical abundance changes that occur along their evolution. Moreover, in the course of their lives, white dwarfs cross different pulsational instability strips. The existence of these instability strips provides astronomers with an unique opportunity to peer into their internal structure that would otherwise remain hidden from observers. We will show that this allows to measure with unprecedented precision the stellar masses and to infer their envelope thicknesses, to probe the core chemical stratification, and to detect rotation rates and magnetic fields. Consequently, in this work, we also review the pulsational properties of white dwarfs and the most recent applications of white dwarf asteroseismology.

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Section: Brief History Of Discoverymentioning

confidence: 99%

Evolutionary and pulsational properties of white dwarf stars

Althaus

Córsico

Isern

et al. 2010

Astron Astrophys Rev

380

372

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“…These periods were not detected at that time, and this led to the conclusion that H burning is not the source of energy in a white dwarf, and allowed Mestel (1952) to elaborate his theory of cooling. The first pulsating white dwarf, HL Tau 76, was discovered by Landolt (1968), with a detected period of ∼740 s, too long to be due to a radial mode (Faulkner & Gribbin 1968;Ostriker & Tassoul 1968). Two additional pulsating white dwarfs, G44-32 (600-800 s) and R548 (200-300 s) (Lasker & Hesser 1969, 1971 were discovered shortly after, but again, the periods measured were too long to be associated with radial modes.…”

Section: A Brief Historical Accountmentioning

confidence: 99%

White-dwarf asteroseismology: An update

Córsico

2019

Proc. IAU

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The vast majority of stars that populate the Universe will end their evolution as white-dwarf stars. Applications of white dwarfs include cosmochronology, evolution of planetary systems, and also as laboratories to study non-standard physics and crystallization. In addition to the knowledge of their surface properties from spectroscopy combined with model atmospheres, the global pulsations that they exhibit during several phases of their evolution allow spying on the deep interior of these stars. Indeed, by means of asteroseismology, an approach based on the comparison between the observed pulsation periods of variable white dwarfs and the periods predicted by representative theoretical models, we can infer details of the internal chemical stratification, the total mass, and even the stellar rotation profile and strength of magnetic fields. In this article, we review the current state of the area, emphasizing the latest findings provided by space-mission data.

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“…1% are kinematically ambiguous with other hypotheses 6. Corrections have been applied for scanning inefficiencies due to the K° lifetime and steeply dipping protons.…”

mentioning

confidence: 99%

“…We shall describe the motions that will ensue in the © and the Z directions by a Lagrangian displacement of the form e&,Z)e i ot (6) [N(-g) 1/2, = 0 (4)…”

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Criterion for the Instability of a Uniformly Rotating Configuration in General Relativity

Chandrasekhar

Friedman

1971

Phys. Rev. Lett.

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Uniformly rotating configurations in general relativity are considered, and a condition is obtained that they can be quasi static ally deformed without violating any of the requirements for equilibrium. This condition extends, into the domain of the rotating stars, the criterion for the onset of dynamical instability (via a neutral mode of oscillation) that occurs by radial pulsations in nonrotating stars.It is now well known that in general relativity spherically symmetric configurations that are stable in the Newtonian theory can become dynamically unstable by a radial mode of oscillation if their radii are less than some determinate values. 1 " 3 It is this general relativistic instability that is responsible, for example, for the existence of a lower limit to the periods of pulsations of white dwarfs and for their exclusion as an interpretation of pulsars. 4 " 7 It is also known 8 " 10 that in the Newtonian theory, rotation has a stabilizing effect on the spherically symmetric mode of dynamical instability in the absence of rotation. If the destabilizing effect of general relativity and the Newtonian stabilizing effect of rotation are considered, each in their lowest orders-0{c~2) in general relativity and 0(£l 2 ) in rotation (c is the velocity of light and £2 is the angular velocity of rotation, assumed uniform)-then it is a simple matter to write down the result of their combined effects on stability. 9 " 11 But so far the problem has not been investigated in the exact framework of general relativity, and the problem is clearly important in the broader context of the collapse of rotating stars.In this Letter we shall show how, by considering infinitesimal quasistatic deformations of uniformly rotating configurations, we can obtain a sufficient condition for the onset of instability in the exact framework of general relativity.The description of the stationary state. -The equations governing the equilibrium of uniformly rotating axisymmetric configurations have recently been written down by several authors. 12 " 14 The form of the metric, which involves no loss of generality and which is convenient for our present purposes, is ds 2 ' + oo e v (d

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Stability and Radial Vibration Periods of the Hamada–Salpeter White Dwarf Models

Cited by 34 publications

References 14 publications

Evolutionary and pulsational properties of white dwarf stars

Evolutionary and pulsational properties of white dwarf stars

White-dwarf asteroseismology: An update

Criterion for the Instability of a Uniformly Rotating Configuration in General Relativity

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