Quantum Radiation Properties of General Nonstationary Black Hole

Using the generalized tortoise coordinate transformations the quantum radiation properties of Klein-Gordon scalar particles, Maxwell's electromagnetic field equations and Dirac equations are investigated in general non-stationary black hole. The locations of the event horizon and the Hawking temperature depend on both time and angles. A new extra coupling effect is observed in the thermal radiation spectrum of Maxwell's equations and Dirac equations which is absent in the thermal radiation spectrum of scalar particles. We also observe that the chemical potential derived from scalar particles is equal to the highest energy of the negative energy state of the scalar particle in the non-thermal radiation in general non-stationary black hole. Applying generalized tortoise coordinate transformation a constant term $\xi$ is produced in the expression of thermal radiation in general non-stationary black hole. It indicates that generalized tortoise coordinate transformation is more accurate and reliable in the study of thermal radiation of black hole.Comment: Accepted in Advances in High Energy Physics, Hindawi Publishing Corporatio

Derivation of Distances with the Tully-Fisher Relation: The Antlia Cluster

The Tully-Fisher relation is a correlation between the luminosity and the HI 21cm line width in spiral galaxies (LLW relation). It is used to derive galaxy distances in the interval 7 to 100 Mpc. Closer, the Cepheids, TRGB and Surface Brightness Fluctuation methods give a better accuracy. Further, the SNIa are luminous objects still available for distance measurement purposes, though with a dramatically lower density grid of measurements on the sky. Galaxies in clusters are all at the same distance from the observer. Thus the distance of the cluster derived from a large number of galaxies (N) has an error reduced according to the square root of N. However, not all galaxies in a cluster are suitable for the LLW measurement. The selection criteria we use are explained hereafter; the important point being to avoid Malmquist bias and to not introduce any systematics in the distance measurement.Comment: Moriond0

Hands-On TAROT: Intercontinental use of the TAROT for Education and Public Outreach

The TAROT telescope has for primary goal the search for the prompt optical counterpart of Cosmic Gamma-Ray Bursts. It is a completely autonomous 25cm telescope installed near Nice (France), able to point any location of the sky within 1-2 seconds. The control, scheduling, and data processing activities are completely automated, so the instrument is completely autonomous. In addition to its un-manned modes, we added recently the possibility to remotely control the telescope, as a request of the "Hands-On Universe" (HOU) program for exchange of time within automatic telescopes for the education and public outreach. To this purpose we developed a simple control interface. A webcam was installed to visualize the telescope. Access to the data is possible through a web interface. The images can be processed by the HOU software, a program specially suited for use within the classroom. We experienced these feature during the open days of the University of California Berkeley and the Astronomy Festival of Fleurance (France). We plan a regular use for an astronomy course of the Museum of Tokyo, as well as for French schools. Not only does Hands-On TAROT gives the general public an access to professional astronomy, but it is also a more general tool to demonstrate the use of a complex automated system, the techniques of data processing and automation. Last but not least, through the use of telescopes located in many countries over the globe, a form of powerful and genuine cooperation between teachers and children from various countries is promoted, with a clear educational goal.Comment: 4 pages, Based on a demonstration presented at the ADASS X Conference, Boston, MA, USA, October 2000, to appear in ASP Conf. Serie

Time scales of Li evolution: a homogeneous analysis of open clusters from ZAMS to late-MS

We have performed a new and homogeneous analysis of all the Li data available in the literature for main sequence stars (spectral-types from late F to K) in open clusters. In the present paper we focus on a detailed investigation of MS Li depletion and its time scales for stars in the 6350-5500 K effective temperature range. For the first time, we were able to constrain the age at which non-standard mixing processes, driving MS Li depletion, appear. We have also shown that MS Li depletion is not a continuous process and cannot be simply described by a t^(-alpha) law. We confirm that depletion becomes ineffective beyond an age of 1-2 Gyr for the majority of the stars, leading to a Li plateau at old ages. We compared the empirical scenario of Li as a function of age with the predictions of three non-standard models. We found that models including only gravity waves as main mixing process are not able to fit the Li vs. age pattern and thus this kind of mixing can be excluded as the predominant mechanism responsible for Li depletion. On the other hand, models including slow mixing induced by rotation and angular momentum loss, and in particular those including also diffusive processes not related to rotation, can explain to some extent the empirical evidence. However, none of the currently proposed models can fit the plateau at old ages.Comment: 20 pages, 10 figures A&A accepte