Related papers: Stability criterion for white dwarfs in Palatini $…
We develop a detailed and self-consistent numerical model for extremely-magnetised white dwarfs, which have been proposed as progenitors of overluminous Type Ia supernovae. This model can describe fully-consistent equilibria of magnetic…
The condition for the existence of self-gravitational solitary waves (SGSWs), and their polarity in any astrophysical compact object are theoretically found for the first time. The pseudo-potential approach, which is valid for arbitrary…
Ultramassive white dwarfs with masses $M\gtrsim 1.1\,{\rm M}_\odot$ probe extreme physics near the Chandrasekhar limit. Despite the rapid increase in observations, it is still unclear how many harbour carbon-oxygen (CO) versus oxygen-neon…
The explosion of a type Ia supernova starts in a white dwarf as a laminar deflagration at the center of the star and soon several hydrodynamic instabilities, in particular, the Rayleigh-Taylor instability, begin to act. A cellular…
Two approaches to the study of cosmological density perturbations in modified theories of Palatini gravity have recently been discussed. These utilise, respectively, a generalisation of Birkhoff's theorem and a direct linearization of the…
We study finite-time blow-up for pseudo-relativistic Hartree- and Hartree-Fock equations, which are model equations for the dynamical evolution of white dwarfs. In particular, we prove that radially symmetric initial configurations with…
In the "double-detonation sub-Chandrasekhar" model for type Ia supernovae, a carbon-oxygen (C + O) white dwarf accumulates sufficient amounts of helium such that a detonation ignites in that layer before the Chandrasekhar mass is reached.…
The maximum mass of a star that can produce a white dwarf (WD) is an important astrophysical quantity. One of the best approaches to establishing this limit is to search for WDs in young star clusters in which only massive stars have had…
This manuscript copes with the issue of analyzing the conditions to check the stability of the pressure isotropy condition by taking into account a spherically symmetric dissipative astrophysical configuration with the Palatini $f(R)$…
For many years it was felt that, when a star collapsed, a white dwarf resulted if the mass of the original star was below the Chandrasekhar limit, a neutron star if the mass was somewhat larger but still less than four or five solar masses,…
Using basic physical arguments, we derive by dimensional and physical analysis the characteristic masses and sizes of important objects in the Universe in terms of just a few fundamental constants. This exercise illustrates the unifying…
Gravitational redshift is a fundamental parameter that allows us to determine the mass-to-radius ratio of compact stellar objects, such as black holes, neutron stars, and white dwarfs (WDs). In the X-ray spectra of the close binary system,…
The Chandrasekhar limit for quark stars is evaluated from simple energy balance relations, as proposed by Landau for white dwarfs or neutron stars. It has been found that the limit for quark stars depends on, in addition to the fundamental…
While Chandrasekhar-mass ($M_{\rm Ch}$) models with a low $^{56}\rm{Ni}$ yield can match the peak luminosities of fast-declining, 91bg-like Type Ia supernovae (SNe Ia), they systematically fail to reproduce their faster light-curve…
Over the last couple of decades, there are direct and indirect evidences for massive compact objects than their conventional counterparts. A couple of such examples are super-Chandrasekhar white dwarfs and massive neutron stars. The…
The approach of dynamical systems is a useful tool to investigate the cosmological history that follows from modified theories of gravity. It provides qualitative information on the typical background solutions in a parametrized family of…
In this paper we derive a bound on the rate of change of the gravitational constant G coming from the pulsating white dwarf G117-B15A. This star is a ZZ Ceti pulsator extensively studied with astroseismological techniques for last three…
The presence of planets around solar-type stars suggests that many white dwarfs should have relic planetary systems. While planets closer than $\sim$ 5~AU will most likely not survive the post-main sequence lifetime of its parent star, any…
While the accretion power in astrophysics has been studied in many astronomical environments, the ``spin--down power'' is often neglected. In this essay I demonstrate that the spin--down power alone may drive a rotating system from…
In this work we derive the covariant and gauge invariant perturbation equations in general theories of $f(R)$ gravity in the Palatini formalism to linear order and calculate the cosmic microwave background (CMB) and matter power spectra for…