Astronomy: Principles and Practice

Roy, A. E.; Clarke, D.

doi:10.1887/0750309172

Cited by 23 publications

(30 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…WEBDA contains photometric data for every cluster star obtained from direct observations: apparent stellar magnitude V and color index (B-V), as well as metallicity [Fe/H], color excess E(B-V), and distance modulus (m-M)V. For calculations, initial photometric data are converted into absolute stellar magnitude MV and normal color index (B-V)0 using the following formulae [18,19]:…”

Section: Photometry-based Methods Of Entropy-production Calculationmentioning

confidence: 99%

“…The entropy production Σ in a star (in the volume inside its photosphere) is determined by nuclear fusions, convection, interaction between radiation and matter, and the like [15]. Let us adopt the most common assumption that a star's photosphere is, on the first approximation, a black body [18,19]. In this case, the radiation thermodynamics is well studied and the simplest.…”

Section: Photometry-based Methods Of Entropy-production Calculationmentioning

confidence: 99%

See 1 more Smart Citation

Entropy Production of Main-Sequence Stars

Martyushev

Zubarev

2015

Entropy

View full text Add to dashboard Cite

Abstract:The entropy production (inside the volume bounded by a photosphere) of main-sequence stars is calculated based on B-V photometry data. The entropy-production distribution function and the dependences of entropy production on temperature and luminosity are obtained for these stars for the first time. A very small range of variation of specific (per volume) entropy production discovered for main-sequence stars (only 0.5 to 1.8 solar magnitudes) is an interesting result that can be crucial for understanding thermodynamic processes of stars.

show abstract

Section: Photometry-based Methods Of Entropy-production Calculationmentioning

confidence: 99%

Section: Photometry-based Methods Of Entropy-production Calculationmentioning

confidence: 99%

Entropy Production of Main-Sequence Stars

Martyushev

Zubarev

2015

Entropy

View full text Add to dashboard Cite

show abstract

“…By analogy with other various fields of Science, also beyond BHs, for example the case of planets and stars. One defines the effective temperature of a body such as a star or planet as the temperature of a black body that would emit the same total amount of electromagnetic radiation [41]. The importance of the effective temperature in a star is stressed by the issue that the effective temperature and the bolometric luminosity are the two fundamental physical parameters needed to place a star on the Hertzsprung-Russell diagram.…”

Section: Introduction: the Black Hole Information Paradoxmentioning

confidence: 99%

Time dependent Schrödinger equation for black hole evaporation: No information loss

Corda

2015

Annals of Physics

294

View full text Add to dashboard Cite

In 1976 S. Hawking claimed that "Because part of the information about the state of the system is lost down the hole, the final situation is represented by a density matrix rather than a pure quantum state"1 . This was the starting point of the popular "black hole (BH) information paradox".In a series of papers, together with collaborators, we naturally interpreted BH quasi-normal modes (QNMs) in terms of quantum levels discussing a model of excited BH somewhat similar to the historical semiclassical Bohr model of the structure of a hydrogen atom. Here we explicitly write down, for the same model, a time dependent Schrödinger equation for the system composed by Hawking radiation and BH QNMs. The physical state and the correspondent wave function are written in terms of an unitary evolution matrix instead of a density matrix. Thus, the final state results to be a pure quantum state instead of a mixed one. Hence, Hawking's claim is falsified because BHs result to be well defined quantum mechanical systems, having ordered, discrete quantum spectra, which respect 't Hooft's assumption that Schröedinger equations can be 1 Verbatim from ref. 2 1 used universally for all dynamics in the universe. As a consequence, information comes out in BH evaporation in terms of pure states in an unitary time dependent evolution.In Section 4 of this paper we show that the present approach permits also to solve the entanglement problem connected with the information paradox.To the memory of the latter IFM Secretary Franco Pettini.

show abstract

“…Moreover, due to perfect black body character of Bose-Einstein and Fermi-Dirac distributions, it is natural to have deviations from these distributions in case of the above effective temperature. Thus in analogy to BH, the effective temperature of a body (say star) can be defined as the temperature of a black body that would emit the same total amount of electromagnetic radiation [14,20]. So, one can consider this effective temperature and the bolometric luminosity as the two fundamental physical parameters to identify a star on the Hertzsprung-Russel diagram.…”

Section: Basic Equations For Tunnelling Approach To Radiation Spectrummentioning

confidence: 99%

“…So, one can consider this effective temperature and the bolometric luminosity as the two fundamental physical parameters to identify a star on the Hertzsprung-Russel diagram. It is worthy to mention here that both the above two physical parameters however depend on the chemical composition of the star [14][15][16][17]20].…”

Section: Basic Equations For Tunnelling Approach To Radiation Spectrummentioning

confidence: 99%

Quantum Corrected Non-Thermal Radiation Spectrum from the Tunnelling Mechanism

2015

View full text Add to dashboard Cite

The tunnelling mechanism is today considered a popular and widely used method in describing Hawking radiation. However, in relation to black hole (BH) emission, this mechanism is mostly used to obtain the Hawking temperature by comparing the probability of emission of an outgoing particle with the Boltzmann factor. On the other hand, Banerjee and Majhi reformulated the tunnelling framework deriving a black body spectrum through the density matrix for the outgoing modes for both the Bose-Einstein distribution and the Fermi-Dirac distribution. In contrast, Parikh and Wilczek introduced a correction term performing an exact calculation of the action for a tunnelling spherically symmetric particle and, as a result, the probability of emission of an outgoing particle corresponds to a non-strictly thermal radiation spectrum. Recently, one of us (C. Corda) introduced a BH effective state and was able to obtain a non-strictly black body spectrum from the tunnelling mechanism corresponding to the probability of emission of an outgoing particle found by Parikh and Wilczek. The present work introduces the quantum corrected effective temperature and the corresponding quantum corrected effective metric is written using Hawking's periodicity arguments. Thus, we obtain further corrections to the non-strictly thermal BH radiation spectrum as the final distributions take into account both the BH Galaxies 2015, 3 104 dynamical geometry during the emission of the particle and the quantum corrections to the semiclassical Hawking temperature.

show abstract

Astronomy: Principles and Practice

Cited by 23 publications

References 0 publications

Entropy Production of Main-Sequence Stars

Entropy Production of Main-Sequence Stars

Time dependent Schrödinger equation for black hole evaporation: No information loss

Quantum Corrected Non-Thermal Radiation Spectrum from the Tunnelling Mechanism

Contact Info

Product

Resources

About