一个实际存在的负能谱系统--白矮星

详细地剖析了初期演化过程中的白矮星的基本特性．在此基础上进一步论述了白矮星是一个实际存在的负能谱系统．     

白矮星是负熵系统

应用正、负能谱热力学理论(PNES热力学理论)，通过白矮星熵的演化对白矮星的初期演化阶段作了仔细分析，得出了白矮星在其初期收缩过程中是一个负熵系统，白矮星的演化由其正熵(电子子系的熵)Se和负熵(氮离子子系的熵)SHe之问的竞争决定，当SHe比Se增长得快时，则系统的总熵将更负，它必将更趋于有序态；反之，当SHe比Se增长得慢时，系统的负熵将减少，于是系统的有序程度将减少．     

白矮星系统--正能谱电子系统与负能谱氦离子系统的复合系统

本文应用正、负能谱系统热力学理论较仔细地分析了白矮星的初期演化过程，其结果虽然与过去有关理论在力学平衡问题上的结论一致，但本文所依据的基础和思路与过去理论大不相同，按原有理论，认为白矮星只是一个高度简并的电子系统，而氦离子系统仅作为约束电子系统的外部条件，显然这个理论模型不能反映白矮星的实际状态，因为白矮星并非一个电子系统。而是由电子与氦离子组成的复合系统。因此，原有理论除了可以描写电子系统的力学平衡外，它根本不可能描述白矮星的演化，本文将白矮星视为电子系统与氦离子系统的复合系统。不仅可以描述白矮星的力学平衡，而且还可通过熵的演化来描写白矮星的演化进程。     

由自引力支配的负能谱系统的稳定性

在正、负能谱热力学理论的基础上建立了正、负能谱系统稳定平衡判据间的互补对应,又根据L.D. Landau关于负能谱系统存在条件的论述,并结合广义相对论中经修改了的较精确的引力公式,论述了高密度自引力塌缩物质是负能谱系统存在的重要形式,最后根据负能谱系统稳定平衡判据论证了负能谱系统平衡态的稳定性.     

一个关于白矮星力学平衡的新理论

将一个新理论——正、负能谱(PNES)热力学理论应用于白矮星系统的力学平衡问题，对白矮星初期淡化阶段的力学平衡进行了详细的分析．虽然应用PNES热力学理论所得出的结论与原有的理论结果一致．但是PNES理论的基本原理和思路与原有的理论完全不同，按照原有理论，白矮星系统只是一种电子系统，氮离子系统只被视为约束电子系统的外部约束条件．显然原有理论不能反映白矮星的实际状态，因为白矮星并不是一个电子系统而是一个由电子子系和氯离子子系组成的复合系统．因此，对白矮星的力学平衡问题和演化问题都必须以由电子子系和氮离子子系组成的复合系统来进行研究．本文应用这一新理论(PNES热力学理论)，以复合系统的观点研究了白矮的力学平衡问题．     

高密度物质是负能谱系统存在的必然形式浇

负能谱的存在,尤其是稳定的负能谱系统的存在是建立负能谱热力学理论的基础性依据.根据Landau关于负能谱和负能谱系统存在的论述,对负能谱存在问题进行了深入探讨.     

高密度物质是负能谱系统存在的必然形式

负能谱的存在，尤其是稳定的负能谱系统的存在是建立负能谱热力学理论的基础性依据．根据Landau关于负能谱和负能谱系统存在的论述，对负能谱存在问题进行了深入探讨．     

稳态黑洞是处于全无界能谱中的系统

对稳态黑洞能谱的基本特征进行了研究．研究表明稳态黑洞是处于全无界能谱中的系统．在其外视界之外正、负能谱之间禁带能隙消失在外视界面上．在外视之外，黑体辐射系统或正能谱系统易于激发；反之，根据Landau的负能谱理论，在外视界之内负能谱系统易于激发．因此，黑洞的外视界是正、负能谱系统的交接面，在黑洞外视界以外黑洞显示为正能谱系统，而在黑洞外视界以内黑洞又显示为负能谱系统．有鉴于此，我们提出了一个判据，利用这个判据可以很容易地确定黑洞的热力学类型．     

再论负能谱系统存在的必然性

根据Landau的负能谱理论，探讨了高密度物质中存在负能谱系统的可能性，首先介绍了Landau的负能谱理论，进一步利用星体内部场的结构方程-TOV方程分别讨论了相对论流体，超相对论流体中形成负能谱的可能性，最后对相对论量子系统中形成负能谱的条件也作了基础性阐述．     

负能谱中的黑洞热力学

根据LandauLD的负能谱论述,论证了高密度自引力系统是实际存在的负能谱系统,进一步以负能谱理论研讨了黑洞的视界温度、熵以及熵的演化.最后,讨论了黑洞的热力学第三定律.     

Infrared spectrum of an extremely cool white-dwarf star

White dwarfs are the remnant cores of stars that initially had masses of less than 8 solar masses. They cool gradually over billions of years, and have been suggested to make up much of the 'dark matter' in the halo of the Milky Way. But extremely cool white dwarfs have proved difficult to detect, owing to both their faintness and their anticipated similarity in colour to other classes of dwarf stars. Recent improved models indicate that white dwarfs are much more blue than previously supposed, suggesting that the earlier searches may have been looking for the wrong kinds of objects. Here we report an infrared spectrum of an extremely cool white dwarf that is consistent with the new models. We determine the star's temperature to be 3,500 +/- 200 K, making it the coolest known white dwarf. The kinematics of this star indicate that it is in the halo of the Milky Way, and the density of such objects implied by the serendipitous discovery of this star is consistent with white dwarfs dominating the dark matter in the halo.     

Survival of a brown dwarf after engulfment by a red giant star

Many sub-stellar companions (usually planets but also some brown dwarfs) orbit solar-type stars. These stars can engulf their sub-stellar companions when they become red giants. This interaction may explain several outstanding problems in astrophysics but it is unclear under what conditions a low mass companion will evaporate, survive the interaction unchanged or gain mass. Observational tests of models for this interaction have been hampered by a lack of positively identified remnants-that is, white dwarf stars with close, sub-stellar companions. The companion to the pre-white dwarf AA Doradus may be a brown dwarf, but the uncertain history of this star and the extreme luminosity difference between the components make it difficult to interpret the observations or to put strong constraints on the models. The magnetic white dwarf SDSS J121209.31 + 013627.7 may have a close brown dwarf companion but little is known about this binary at present. Here we report the discovery of a brown dwarf in a short period orbit around a white dwarf. The properties of both stars in this binary can be directly observed and show that the brown dwarf was engulfed by a red giant but that this had little effect on it.     

Supernova SN 2011fe from an exploding carbon-oxygen white dwarf star

Type Ia supernovae have been used empirically as 'standard candles' to demonstrate the acceleration of the expansion of the Universe even though fundamental details, such as the nature of their progenitor systems and how the stars explode, remain a mystery. There is consensus that a white dwarf star explodes after accreting matter in a binary system, but the secondary body could be anything from a main-sequence star to a red giant, or even another white dwarf. This uncertainty stems from the fact that no recent type Ia supernova has been discovered close enough to Earth to detect the stars before explosion. Here we report early observations of supernova SN 2011fe in the galaxy M101 at a distance from Earth of 6.4 megaparsecs. We find that the exploding star was probably a carbon-oxygen white dwarf, and from the lack of an early shock we conclude that the companion was probably a main-sequence star. Early spectroscopy shows high-velocity oxygen that slows rapidly, on a timescale of hours, and extensive mixing of newly synthesized intermediate-mass elements in the outermost layers of the supernova. A companion paper uses pre-explosion images to rule out luminous red giants and most helium stars as companions to the progenitor.     

The age of the Milky Way inner halo

The Milky Way galaxy has several components, such as the bulge, disk and halo. Unravelling the assembly history of these stellar populations is often restricted because of difficulties in measuring accurate ages for low-mass, hydrogen-burning stars. Unlike these progenitors, white dwarf stars, the 'cinders' of stellar evolution, are remarkably simple objects and their fundamental properties can be measured with little ambiguity. Here I report observations of newly formed white dwarf stars in the halo of the Milky Way, and a separate analysis of archival data in the well studied 12.5-billion-year-old globular cluster Messier 4. I measure the mass distribution of the remnant stars and invert the stellar evolution process to develop a mathematical relation that links this final stellar mass to the mass of their immediate progenitors, and therefore to the age of the parent population. By applying this technique to a small sample of four nearby and kinematically confirmed halo white dwarf stars, I calculate the age of local field halo stars to be 11.4?±?0.7 billion years. The oldest globular clusters formed 13.5?billion years ago. Future observations of newly formed white dwarf stars in the halo could be used to reduce the uncertainty, and to probe relative differences between the formation times of the youngest globular clusters and the inner halo.     

The type Ia supernova SNLS-03D3bb from a super-Chandrasekhar-mass white dwarf star

The accelerating expansion of the Universe, and the need for dark energy, were inferred from observations of type Ia supernovae. There is a consensus that type Ia supernovae are thermonuclear explosions that destroy carbon-oxygen white dwarf stars that have accreted matter from a companion star, although the nature of this companion remains uncertain. These supernovae are thought to be reliable distance indicators because they have a standard amount of fuel and a uniform trigger: they are predicted to explode when the mass of the white dwarf nears the Chandrasekhar mass of 1.4 solar masses (M(o)). Here we show that the high-redshift supernova SNLS-03D3bb has an exceptionally high luminosity and low kinetic energy that both imply a super-Chandrasekhar-mass progenitor. Super-Chandrasekhar-mass supernovae should occur preferentially in a young stellar population, so this may provide an explanation for the observed trend that overluminous type Ia supernovae occur only in 'young' environments. As this supernova does not obey the relations that allow type Ia supernovae to be calibrated as standard candles, and as no counterparts have been found at low redshift, future cosmology studies will have to consider possible contamination from such events.     

Exclusion of a luminous red giant as a companion star to the progenitor of supernova SN 2011fe

Type Ia supernovae are thought to result from a thermonuclear explosion of an accreting white dwarf in a binary system, but little is known of the precise nature of the companion star and the physical properties of the progenitor system. There are two classes of models: double-degenerate (involving two white dwarfs in a close binary system) and single-degenerate models. In the latter, the primary white dwarf accretes material from a secondary companion until conditions are such that carbon ignites, at a mass of 1.38 times the mass of the Sun. The type Ia supernova SN 2011fe was recently detected in a nearby galaxy. Here we report an analysis of archival images of the location of SN 2011fe. The luminosity of the progenitor system (especially the companion star) is 10-100 times fainter than previous limits on other type Ia supernova progenitor systems, allowing us to rule out luminous red giants and almost all helium stars as the mass-donating companion to the exploding white dwarf.