General Relativistic and Newtonian White Dwarfs

Boshkayev, Kuantay; Rueda, J. A.; Ruffini, Remo; Siutsou, I. A.

doi:10.1142/9789814623995_0472

Cited by 9 publications

(9 citation statements)

References 18 publications

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“…As relatively few BDs are known and ages are difficult to constrain empirically, we rely on theoretical models to determine their luminosity L BD and effective temperature T ef f . Two standard models are available (Burrows et al 1997;Baraffe et al 2003) and their results are shown in Fig. 2.…”

Section: Brown Dwarf Coolingmentioning

confidence: 99%

“…BDs are objects that are not massive enough to produce the central pressures necessary to fuse hydrogen into helium. Nonetheless, BDs can support an HZ as their slow contraction converts gravitational energy into heat (Burrows et al 1997; Baraffe et al 2003). The habitability of planets about BDs has received less attention than habitability of planets orbiting hydrogen-burning stars, as a) relatively few are known, b) it is unknown if planets can form around them, and c) they are very faint.…”

Section: Introductionmentioning

confidence: 99%

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Habitable Planets Around White and Brown Dwarfs: The Perils of a Cooling Primary

Barnes

Heller

2013

Astrobiology

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White and brown dwarfs are astrophysical objects that are bright enough to support an insolation habitable zone (IHZ). Unlike hydrogen-burning stars, they cool and become less luminous with time; hence their IHZ moves in with time. The inner edge of the IHZ is defined as the orbital radius at which a planet may enter a moist or runaway greenhouse, phenomena that can remove a planet's surface water forever. Thus, as the IHZ moves in, planets that enter it may no longer have any water and are still uninhabitable. Additionally, the close proximity of the IHZ to the primary leads to concern that tidal heating may also be strong enough to trigger a runaway greenhouse, even for orbital eccentricities as small as 10 -6 . Water loss occurs due to photolyzation by UV photons in the planetary stratosphere, followed by hydrogen escape. Young white dwarfs emit a large amount of these photons, as their surface temperatures are over 10 4 K. The situation is less clear for brown dwarfs, as observational data do not constrain their early activity and UV emission very well. Nonetheless, both types of planets are at risk of never achieving habitable conditions, but planets orbiting white dwarfs may be less likely to sustain life than those orbiting brown dwarfs. We consider the future habitability of the planet candidates KOI 55.01 and 55.02 in these terms and find they are unlikely to become habitable.

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Section: Brown Dwarf Coolingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Habitable Planets Around White and Brown Dwarfs: The Perils of a Cooling Primary

Barnes

Heller

2013

Astrobiology

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“…Summarizing those results: they showed that the rotation can have astrophysical implications to Soft-Gamma Repeaters and Anomalous X-Ray Pulsars, rotation can also uplift slightly the maximum stable mass configuration and they also showed that the spin-up and spindown eras are different for sub and super-Chandrasekhar WD. In addition, in [31] the authors compare the results of general relativistic uniformly-rotating WD with uniformly-rotating Newtonian WD. In light of uniformlyrotating case the minimum rotation period is about the same in both cases (general relativistic and Newtonian) and the general relativistic maximum mass is slightly below the Newtonian maximum mass.…”

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confidence: 99%

General relativistic effects in the structure of massive white dwarfs

2018

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In this work we investigate the structure of white dwarfs using the Tolman-Oppenheimer-Volkoff equations and compare our results with those obtained from Newtonian equations of gravitation in order to put in evidence the importance of General Relativity (GR) for the structure of such stars. We consider in this work for the matter inside white dwarfs two equations of state, frequently found in the literature, namely, the Chandrasekhar and Salpeter equations of state. We find that using Newtonian equilibrium equations, the radii of massive white dwarfs (M > 1.3M ) are overestimated in comparison with GR outcomes. For a mass of 1.415M the white dwarf radius predicted by GR is about 33% smaller than the Newtonian one. Hence, in this case, for the surface gravity the difference between the general relativistic and Newtonian outcomes is about 65%. We depict the general relativistic massradius diagrams as M/M = R/(a + bR + cR 2 + dR 3 + kR 4 ), where a, b, c and d are parameters obtained from a fitting procedure of the numerical results and k = (2.08×10 −6 R ) −1 , being R the radius of the Sun in km. Lastly, we point out that GR plays an important role to determine any physical quantity that depends, simultaneously, on the mass and radius of massive white dwarfs.

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“…This EoS is one of many stiff equations of state which are in accordance with the observational constraints on NSs [69]. The degenerate electron gas EoS was employed for the WD matter [81,82] as it is the simplest EoS.…”

Section: Rotating White Dwarfs and Neutron Starsmentioning

confidence: 87%

Neutrino oscillation in the q-metric

2020

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We investigate neutrino oscillation in the field of an axially symmetric space-time, employing the so-called q-metric, in the context of general relativity. Following the standard approach, we compute the phase shift invoking the weak and strong field limits and small deformation. To do so, we consider neutron stars, white dwarfs and supernovae as strong gravitational regimes whereas the solar system as weak field regime. We argue that the inclusion of the quadrupole parameter leads to the modification of the well-known results coming from the spherical solution due to the Schwarschild space-time. Hence, we show that in the solar system regime, considering the Earth and Sun, there is a weak probability to detect deviations from the flat case, differently from the case of neutron stars and white dwarfs in which this probability is larger. Thus, we heuristically discuss some implications on constraining the free parameters of the phase shift by means of astrophysical neutrinos. A few consequences in cosmology and possible applications for future space experiments are also discussed throughout the text.

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General Relativistic and Newtonian White Dwarfs

Cited by 9 publications

References 18 publications

Habitable Planets Around White and Brown Dwarfs: The Perils of a Cooling Primary

Habitable Planets Around White and Brown Dwarfs: The Perils of a Cooling Primary

General relativistic effects in the structure of massive white dwarfs

Neutrino oscillation in the q-metric

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