The radial effective temperature distribution of steady-state, mass-losing accretion disks

Mass loss appears to be a common phenomenon among disk-accreting astrophysical systems. An outflow emanating from an accretion disk can act as a sink for mass, angular momentum and energy and can therefore alter the dissipation rates and effective temperatures across the disk. Here, the radial distributions of dissipation rate and effective temperature across a Keplerian, steady-state, mass-losing accretion disk are derived, using a simple, parametric approach that is sufficiently general to be applicable to many types of dynamical disk wind models. Effective temperature distributions for mass-losing accretion disks in cataclysmic variables are shown explicitly, with parameters chosen to describe both radiation-driven and centrifugally-driven outflows. For realistic wind mass-loss rates of a few percent, only centrifugally-driven outflows -- particularly those in which mass loss is concentrated in the inner disk -- are likely to alter the disk's effective temperature distribution significantly. Accretion disks that drive such outflows could produce spectra and eclipse light curves that are noticeably different from those produced by standard, conservative disks.Comment: 14 pages, 3 figures, accepted for publication in MNRA

The voluntary welfare associations in Germany: An overview

The traditional role of voluntary welfare associations has changed and will change further on. Recent legislation strongly influenced by the European Union largely abolished their prominent and privileged role in corporatism. The traditional way of co-operation was substituted with new forms of welfare-mix and welfare-pluralism including more and more other private non-profit, but also for-profit providers of social welfare and services. Partly the voluntary welfare associations have already adjusted themselves to these new problems and challenges. Main tasks however still must be fulfilled to find the future role under changed framework conditions: -The new balance of different interests of traditional member organizations and providers of social services, -the maintaining of the leading role as providers of social services in the 'new world' of welfare-pluralism and market-orientation and the necessary integration of new approaches of self-help, voluntary and charity work. -- Die traditionelle Rolle der Freien Wohlfahrtspflege hat sich verändert und wird sich weiter verändern. Die Gesetzgebung der vergangenen Jahre, die stark von der Europäischen Union beeinflusst wurde, hat ihre hervorgehobene und privilegierte Stellung im korporatistischen System beseitigt. Die traditionelle Kooperation wurde durch neue Formen des Wohlfahrtsmix und Wohlfahrtspluralismus ersetzt, zu dem immer mehr andere gemeinnützige, aber auch gewerbliche Anbieter sozialer Dienste gehören. Teilweise hat sich die Freie Wohlfahrtspflege schon auf diese neuen Probleme und Herausforderungen eingestellt. Viele Aufgaben müssen aber in der Zukunft unter veränderten Rahmenbedingungen noch in Angriff genommen werden: - Eine neue Balance unterschiedlicher Interesse von traditionellen Mitgliederorganisationen und Anbietern sozialer Dienste, - die Behauptung der führenden Rolle als Anbieter sozialer Dienst in der 'neuen Welt' von Wohlfahrtspluralismus und Marktorientierung und - die notwendige Integration neuer Ansätze von Selbsthilfe und bürgerschaftlichem Engagement.

The orbital period and system parameters of the recurrent nova T Pyx

T Pyx is a luminous recurrent nova that accretes at a much higher rate than is expected for its photometrically determined orbital period of about 1.8 h. We here provide the first spectroscopic confirmation of the orbital period, P = 1.8295 h (f = 13.118368 +/- 1.1 x 10(-5) c d(-1)), based on time-resolved optical spectroscopy obtained at the Very Large Telescope and the Magellan telescope. We also derive an upper limit of the velocity semi-amplitude of the white dwarf, K 1 = 17.9 +/- 1.6 kms(-1), and estimate amass ratio of q = 0.20 +/- 0.03. If the mass of the donor star is estimated using the period-density relation and theoretical main-sequence mass-radius relation for a slightly inflated donor star, we find M-2 = 0.14 +/- 0.03 M-circle dot. This implies a mass of the primary white dwarf of M-1 = 0.7 +/- 0.2 M-circle dot. If the white-dwarf mass is > 1 M-circle dot, as classical nova models imply, the donor mass must be even higher. We therefore rule out the possibility that T Pyx has evolved beyond the period minimum for cataclysmic variables. We find that the system inclination is constrained to be i approximate to 10 degrees, confirming the expectation that T Pyx is a low-inclination system. We also discuss some of the evolutionary implications of the emerging physical picture of T Pyx. In particular, we show that epochs of enhanced mass transfer (like the present) may accelerate or even dominate the overall evolution of the system, even if they are relatively short-lived. We also point out that such phases may be relevant to the evolution of cataclysmic variables more generally

Inflation after WMAP3

I discuss the current status of inflationary cosmology in light of the recent WMAP 3-year data release. The basic predictions of inflation are all supported by the data. Inflation also makes predictions which have not been well tested by current data but can be by future experiments, most notably a deviation from a scale-invariant power spectrum and the production of primordial gravitational waves. A scale-invariant spectrum is disfavored by current data, but not conclusively. Tensor modes are currently poorly constrained, and slow-roll inflation does not make an unambiguous prediction of the expected amplitude of primordial gravitational waves. A tensor/scalar ratio of $r \simeq 0.01$ is within reach of near-future measurements.Comment: To appear in the proceedings of Colliders to Cosmic Rays 2007. 8 pages, 2 figures. (V2: Minor typo corrected

CSS091109:035759+102943 - a candidate polar

We report optical time-resolved photometry of the CRTS transient CSS091109:035759+102943. Pronounced orbital variability with a 114 min period, large X-ray variability and the IR to X-ray spectral energy distribution suggest a classification as a magnetic cataclysmic binary, a likely AM Herculis star or polar.Comment: Astronomische Nachrichten, in press (4 pages, 4 figures

Episodic absorption in the outflow of V603 Aquilae

We report on the time-dependent behaviour of ultraviolet spectral lines in Hubble Space Telescope Goddard High-Resolution Spectrograph data of the classical nova V603 Aql. In particular, episodic blueshifted absorption (extending to ∼−2500 km s−1) is present, with a variability time-scale down to ∼1 min. The data provide a rare opportunity to study the rapid evolution of absorption structures that may be associated with accretion-disc winds in cataclysmic variables. At least three absorption events are recorded (at blueward velocities only) over ∼5 h, each lasting ∼10–15 min. The derived velocity, acceleration and optical depth properties provide an empirical picture of stochastically variable structures in the outflow, with no evidence for short-term (less than ∼1 h) cyclic or modulated behaviour in the overall absorption properties. In contrast, the emission components of the ultraviolet resonance lines are very stable in velocity and strength in this low-inclination system. On at least two occasions there is an intriguing short-term ‘flare’ in the ultraviolet continuum flux (of up to ∼40 per cent). Though there is no clear one-to-one relation in these data between the continuum fluctuations and the occurrence of the absorption events, the time-scales for the two variable phenomena are essentially the same. The irregular absorption episodes in the ultraviolet data of V603 Aql presently defy a clear physical interpretation. Their overall characteristics are discussed in the context of instabilities in radiation-pressure-driven disc winds