Dead Stars Research Articles

QUANTUM CONDENSATES IN EXTREME GRAVITY: IMPLICATIONS FOR COLD STARS AND DARK MATTER

Stable end-point stars currently fall into two distinct classes — white dwarfs and neutron stars — differing enormously in central density and radial size. No stable cold dead stars are thought to span the intervening densities or have masses beyond ~2–3 solar masses. I show, however, that the general-relativistic condition of hydrostatic equilibrium augmented by the equation of state of a neutron condensate at 0 K generates stable sequences of cold stars that span the density gap and can have masses well beyond prevailing limits. The radial sizes and mass limit of each sequence are determined by the mass and scattering length of the composite bosons. Solutions for hypothetical bosons of ultrasmall mass and large scattering length yield huge self-gravitating systems of low density, resembling galactic dark matter halos.

'Welcome to the Atrocity Exhibition': Ian Curtis, Rock Death, and Disability

Since the 1960's, rock music's countercultural aesthetic has willingly and exploitatively appropriated images and cultural attitudes equating disability with freak show spectacle, linking the figure of the self-destructive rock star to the supposedly tragic and socially ostracized "freak." This tendency manifests itself in many forms, from "freakish" concert performances (e.g., heavy metal acts using persons with disabilities as part of their live stage show) to the excessive mythologizing of dead rock stars. The life of Ian Curtis, singer of the seminal post-punk band Joy Division, provides a useful case study for how ableist values have permeated rock music, metaphorically conflating rock stardom with freakery in potentially negative ways for actual persons with disabilities. There currently exists very little scholarship on disability in popular, non-classical music, but I hope this essay will encourage further work.

Planets May Form Around Dead Stars

Planets May Form Around Dead Stars

Light from Dead Stars: The Procedural Adequate and Independent State Ground Reconsidered

Light from Dead Stars: The Procedural Adequate and Independent State Ground Reconsidered

Dead Stars May Masquerade as Ingenues

Science NewsVolume 158, Issue 4 p. 55-55 Of the Week Dead stars may masquerade as ingenues Ron Cowen, Ron CowenSearch for more papers by this author Ron Cowen, Ron CowenSearch for more papers by this author First published: 01 July 2009 https://doi.org/10.2307/3981349AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume158, Issue422 July 2000Pages 55-55 RelatedInformation

Pulsar velocities

Radio pulsars have long been established as having high velocities that are probably produced in the violence of their formation in Supernovae (Gunn & Ostriker 1970; Lyne, Anderson & Salter 1982). Three recent developments have resulted in a reassessment of their velocities: the adoption of a new distance scale (Taylor & Cordes 1993), many new determinations of proper motion (Harrison, Lyne & Anderson 1993; Bailes et al. 1989; Fomalont et al. 1992) and the realisation (Harrison & Lyne 1993) that estimates of speeds derived from scintillation measurements were systematically low by about a factor of 2. Taking into account a strong selection effect that makes the observed velocities unrepresentative of those acquired at birth, it seems that the mean space velocity of pulsars at birth is 450 ± 90 km s-1 (Lyne and Lorimer 1994), about a factor of 3 greater than earlier estimates. The general migration from the Galactic plane is consistent with birth in the supernova of massive Population I stars. An outstanding question is how such velocities are produced in the kinetics of supernova collapse. This large increase in birth velocity is likely to have a major impact upon our understanding of the retention of neutron stars in binary systems, globular clusters and the Galaxy as it exceeds or is comparable with all their escape velocities. The rapid spatial separation of fast and slow pulsars will have a profound effect upon calculations of the galactic population and birth rate, both of which have been underestimated in the past. Furthermore, the distribution of dead neutron stars will be more isotropic and may better match the distribution of the gamma-ray burst sources. A small number of pulsars are at a large distance from the Galactic plane, but moving towards it. The most likely origin of these objects lies in OB runaway stars.

Interstellar dust, chirality, comets and the origins of life: Life from dead stars?

The physical, chemical and astrophysical processes by which chiral prebiotic molecules can be produced in interstellar dust and later delivered “safely” to the earth are considered. A laboratory analog experiment on the irradiation by circularly polarized UV light of mirror image molecules at the low temperatures of interstellar dust demonstrates that a substantial degree of chirality can be produced by irradiation of the dust by circularly polarized light from pulsars whose mean brightness and distribution in the Milky Way provide the energetic photons. The chirality is then preserved by cold aggregation of the dust into low density fragile nuclei. The thermal evolution of comets following them from birth through billions of years in the Oort cloud and back to the inner solar system results in preservation of dust organics in largely pristine form — even including effects of radiogenic heating. Physical justification for the cushioned transfer of fragments of the fluffy comets impacting the earth's atmosphere provides a conceptual basis for depositing significant concentrations of interstellar prebiotic molecules. Chiral amplification in water on the earth is presumed to be enhanced by this local concentration. If chiral molecules are discovered in comet nucleus material which will some day be returned to the laboratory, we may have in our hands the same building blocks from which we evolved.

Jupiters around dead stars and the formation of single recycled radio pulsars

The evolution of a close binary consisting of a white dwarf, neutron star, or black hole in a pair with a low-mass degenerate dwarf is calculated in the stage of mass transfer up to the point at which the dwarf is transformed into a giant planet. A process of "enhanced evaporation" of a dwarf from a binary system in a globular cluster, leading to the formation of an isolated millisecond pulsar, is considered.

From X-ray binaries to binary and millisecond pulsars

Observational evidence on binary and millisecond pulsars indicates that these neutrons starts have been “recycled” in binary systems, i.e. have been spun up by accretion after substantial decay of their surface magnetic fields. There are two groups of binary pulsars, the PSR 1913+16-group, which descended from massive X-ray binaries, and the PSR 1953+29-group, which descended from fairly wide low-mass X-ray binaries. At least several neutron stars in the second group have formed by the accretion-induced collapse of a massive white dwarf. The companion stars in both group of systems are expected to be dead stars, i.e. white dwarfts or neutron stars. The large total number of millisecond binary pulsars in the galaxy (≈10 4), indicates that magnetic fields of nuetron starts do not decay below a value of order 10 9 G. Single millisecond pulsars may have lost their companions in various ways. In globular clusters this is most likely to have happened as a conseqeunce of a collision induced by the passage of a third star. Of order 10 2 single millisecond pulsars may have been formed in this way, of which about one third escaped from their clusters. Single millisecond pulsars outside globular clusters may also have formed by coalescence with a close companion, most probably a white dwarf.

Millisecond Pulsar Formation and Evolution

The evolutionary history of binary radio pulsars, including the two millisecond binary pulsars, is reviewed. There are two groups of binary pulsars, the PSR 1913+16-group, which descended from massive X-ray binaries, and the PSR 1953+29-group, which descended from fairly wide low-mass X-ray binaries. The neutron stars in the second group probably formed by the accretion-induced collapse of a massive white dwarf. The companion stars in both groups of systems are expected to be dead stars, i.e. white dwarfs or neutron stars.The large total number of millisecond binary pulsars in the galaxy (∼ 104), indicates that magnetic fields of neutron stars do not decay below a value of order 109 G. Possible explanations for this phenomenon are discussed.Coalescence with a close degenerate companion provides a viable model for the formation of the single millisecond pulsar.

Luminous Stellar Content of the Galaxy: Inferences from Radio and Infrared Data

Lyman continuum (Lyc) photon production rates can be estimated from radio free-free emission and used to estimate the star formation rate (SFR) of 0 stars. If this SFR is linked to the total SFR through a constant IMF (m ≳0.1 m⊙) one derives for our Galaxy a present-day SFR of ∼10 m⊙ yr−1, which is close to the average SFR over the age of the galactic disk. This is difficult to reconcile with a formation law of the form SFR φ∝Mgask with k>0 which yields SFRs which decrease with time. Even more severe is the fact that the mass distribution of the galactic disk cannot be reproduced by the present-day SFR with a constant IMF. Bimodal star formation, however, reduces the rate at which matter is permanently locked up in low mass and dead stars by nearly a factor of three, and gets reasonable agreement between the present-day distribution of stellar mass and lock-up rate. Bimodal star formation means that stars with m >0.1 m⊙ form in the interarm region while in spiral arms induced star formation produces only stars with m >mc ∼2–3 m⊙.

Mass extinctions and missing matter

The possible influence of 'invisible matter' on the solar system's comet halo, and therefore on quasi-periodic cometary bombardment of the earth and consequent mass extinctions, is briefly addressed. Invisible matter consisting of small or cold interstellar molecular clouds could significantly modulate the comet background flux, while invisible matter consisting of a large population of old, dead stars with a relatively small galactic concentration probably could not. It is also shown that the downward force exerted by the Galaxy will perturb the halo, but will not produce any periodicity.

Can galactic halos be made of baryons?

Several arguments are presented indicating that the apparently non-luminous matter forming massive halos of spiral galaxies is not baryonic. There are difficulties with a halo dominated by gas, snowballs, dust and rocks, jupiters, low mass stars, dead stars and neutron stars. Also, halos may not be composed of black holes unless they are either extremely efficiently accreting or primordial. Consequently, it appears that a significant fraction of the universe may be in the form of massive neutrinos, gravitinos, monopoles, etc.

A Theory of Galactic Nuclei and Quasi-Stellar Objects

view Abstract Citations (1) References (35) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS A Theory of Galactic Nuclei and Quasi-Stellar Objects Opher, Reuven Abstract A theory is presented based on the assumption that interactions are cosmologically induced, resulting in depressed coupling constants in very compact objects (VCOs) which are identified with QSOs and galactic nuclei. The resulting model is that of a nuclear-burning shell surrounding an inert core. The shell thickness 1, the single parameter of the theory, is in units of the Schwarzschild radius of the VCO and is much less than 1. The theory predicts: (1) The total mass (or energy/c2) emitted can be greater than the gravitational mass Mg. Although the law of conservation of energy is not violated, an apparent creation of matter can be observed. (2) The luminosity 1038 M8 ergs 1 (Mg in units of M0). (3) The lifetime l0 /l years. (4) The minimum period of oscillation 10-10 Mg/i days. (5) Only Mg 1 can form black holes; (6) Mg Mt (total mass). According to prediction (1), for example, a galactic nucleus M8 can emit a mass Am every At years and have Mg ( /At)Am > Mg, where Mg is the total mass emitted during the lifetime of the nucleus (mass accretion is assumed to be negligible). Observationally Seyfert nuclei show evidence of having Mg < 3 10 M0, Am _ l0 -10 M0, At l0Th108 years, T > 10 years, and Mg > M0. In support of prediction (6) massive dead stars in a globular cluster should gravitate to the center in log-log years and form a VCO; experimentally Mg/Mt 1 is indicated for the dead stars. The above predictions are discussed and compared with existing astrophysical data. Subject headings: black holes - elementary particles - galactic nuclei - quasi-stellar sources or objects Publication: The Astrophysical Journal Pub Date: February 1974 DOI: 10.1086/152706 Bibcode: 1974ApJ...188..201O full text sources ADS |

THE DEAD STARS OF POPULATION I

THE DEAD STARS OF POPULATION I