Observational asteroseismology of hot subdwarf stars

Hot subdwarf stars are particularly challenging for asteroseismology due to their rapid pulsation periods, intrinsic faintness and relative rarity both in the field and in clusters. These features have ensured that the preferred method of observation up to now has been white-light photometry, and all asteroseismological solutions to date have been made by model fitting of the frequency spectrum. Several attempts have been made to perform asteroseismology using time-resolved spectroscopy on the brightest of these stars, but with modest results. A few attempts at simultaneous multi-color photometry have also been made to identify modes with the amplitude ratio method. We will review the most recent observational results and progress in improving the observational methods for ground-based asteroseismology of these compact pulsators.Comment: 8 pages, to appear in Astronomische Nachrichten, Vol. 331, 102

A Radial Velocity Study of Composite-Spectra Hot Subdwarf Stars with the Hobby-Eberly Telescope

Many hot subdwarf stars show composite spectral energy distributions indicative of cool main sequence companions. Binary population synthesis (BPS) models demonstrate such systems can be formed via Roche lobe overflow or common envelope evolution but disagree on whether the resulting orbital periods will be long (years) or short (days). Few studies have been carried out to assess the orbital parameters of these spectroscopic composite binaries; current observations suggest the periods are long. To help address this problem, we selected fifteen moderately-bright (V~13) hot subdwarfs with F-K dwarf companions and monitored their radial velocities (RVs) from January 2005 to July 2008 using the bench-mounted Medium Resolution Spectrograph on the Hobby-Eberly Telescope (HET). Here we describe the details of our observing, reduction, and analysis techniques and present preliminary results for all targets. By combining the HET data with recent observations from the Mercator telescope, we are able to calculate precise orbital solutions for three systems using more than 6 years of observations. We also present an up-to-date period histogram for all known hot subdwarf binaries, which suggests those with F-K main sequence companions tend to have orbital periods on the order of several years. Such long periods challenge the predictions of conventional BPS models, although a larger sample is needed for a thorough assessment of the models' predictive success. Lastly, one of our targets has an eccentric orbit, implying some composite-spectrum systems might have formerly been hierarchical triple systems, in which the inner binary merged to create the hot subdwarf.Comment: Published in The Astrophysical Journal, Volume 758, Issue 1, article id. 58 (2012). References updated and Equation (5) corrected. 12 pages, 5 figures, 5 table

KIC 1718290: A Helium-rich V1093-Her-like Pulsator on the Blue Horizontal Branch

We introduce the first g-mode pulsator found to reside on the classical blue horizontal branch. One year of Kepler observations of KIC 1718290 reveals a rich spectrum of low-amplitude modes with periods between one and twelve hours, most of which follow a regular spacing of 276.3 s. This mode structure strongly resembles that of the V1093Her pulsators, with only a slight shift towards longer periods. Our spectroscopy, however, reveals KIC 1718290 to be quite distinct from the sdB stars that show V1093Her pulsations, which all have surface gravities higher than log g = 5.1 and helium abundances depleted by at least an order of magnitude relative to the solar composition. We find that KIC1718290 has T_eff = 22 100K, log g = 4.72, and a super-solar helium abundance (log N(He)/N(H) = -0.45). This places it well above the extreme horizontal branch, and rather on the very blue end of the classical horizontal branch, where shell hydrogen burning is present. We conclude that KIC 1718290 must have suffered extreme mass loss during its first giant stage, but not sufficient to reach the extreme horizontal branch.Comment: Accepted for publication in ApJ

J08069+1527: A newly discovered high amplitude, hybrid subdwarf B pulsator

We present our discovery of a new hybrid pulsating subdwarf B star, J08069+1527. The effective temperature and surface gravity of 28,500$\pm$400\,K and 5.37$\pm$0.04\,dex, respectively, place this object inside the instability strip and also among other pulsating hot subdwarfs of a hybrid nature, right next to another fascinating star: Balloon\,090100001. From this proximity, we anticipated this star could pulsate in both high and low frequency modes. Indeed, our analysis of photometric data confirmed our prediction. We detected two peaks in the high frequency region and two other peaks at low frequencies. In addition, the amplitude of the dominant mode is very high and comparable to the dominant peaks in other hybrid subdwarf B stars. Since this star is bright, we performed time-series low resolution spectroscopy. Despite a low signal-to-noise (S/N) ratio, we were able to detect the main peak from these data. All our results strongly indicate that J08069+1527 is a high amplitude pulsating hot subdwarf B star of hybrid nature. By analogy to the other pulsating sdB star, we judge that the dominant mode we detected here has radial nature. Future stellar modeling should provide us with quite good constrains as p- and g-modes presented in this star are driven in different parts of its interior.Comment: 7 pages, 10 figures, accepted for publication in MNRA

Antirheumatische Therapie und Reproduktion: Einfluss auf Fertilität, Schwangerschaft und Stillzeit

Zusammenfassung: Antirheumatische Medikamente können bei männlichen und weiblichen Patienten einen negativen Einfluss auf die Fortpflanzung haben. Mögliche negative Effekte sind: Beeinträchtigung der Fertiltät, Fruchtschädigung während der Schwangerschaft und Nebenwirkungen beim gestillten Kind. Bei der Frau können nichtsteroidale Antiphlogistika (NSAR) und Cyclophosphamid die Fertilität beeinträchtigen. Beim Mann kann Infertilität bei der Behandlung mit Salazopyrin und Cyclophosphamid auftreten. Vor dem Start einer Therapie mit Basistherapeutika sollte abgeklärt sein, ob ein Kinderwunsch besteht. Die Behandlung mit NSAR ist in einigen Abschnitten der Schwangerschaft möglich, ebenso können sie während der Stillzeit eingesetzt werden. Eine begrenzte Anzahl von Basistherapeutika sind mit einer Schwangerschaft vereinbar und werden vorgestellt. Medikamente wie Zytostatika und Leflunomid erfordern prophylaktisches Absetzen bereits vor einer geplanten Schwangerschaft. TNFα-Blocker müssen bei Eintritt einer Schwangerschaft abgesetzt werden. Bei Medikamenten, die toxisch für die Gonaden sind oder fruchtschädigend wirken können, muss während der Anwendung sicher verhütet werden. Die Anwendung von immunsuppressiven Medikamenten während der Stillzeit ist wegen unzureichender Datenlage sehr begrenz

The Impact of Local Public Services and Geographical Cost of Living Differences on Poverty Estimates

Despite a broad consensus on the need to take into account the value of public services and geographical cost of living differences when measuring poverty, there is little reliable evidence on how these factors actually affect poverty estimates. Unlike the standard approach in studies of the distribution of public services, this paper employs a method for valuing sector-specific local public services that allows for differences between municipalities in unit costs for providing public services. Furthermore, recipient frequencies in various demographic groups are used as the basis for determining the allocation of the value of these services on citizens of the municipalities. Geographical differences in living costs are taken into account by using municipal housing price indices or by replacing the country-specific poverty line with municipal-specific poverty lines. Applying Norwegian register data for the period 1993-2001, we find that disregarding the value of local public services and geographical cost of living differences yields a misleading picture of poverty.geographical cost of living differences, in-kind transfers, public services, poverty, housing price indices, municipal-specific poverty lines

Asteroseismology and evolution of EHB stars

The properties of the Extreme Horizontal Branch stars are quite well understood, but much uncertainty surrounds the many paths that bring a star to this peculiar configuration. Asteroseismology of pulsating EHB stars has been performed on a number of objects, bringing us to the stage where comparisons of the inferred properties with evolutionary models becomes feasible. In this review I outline our current understanding of the formation and evolution of these stars, with emphasis on recent progress. The aim is to show how the physical parameters derived by asteroseismology can enable the discrimination between different evolutionary models.Comment: 13 pages, 6 figures, invited review to appear in Communications in Asteroseismology vol.159, "Proceedings of the JENAM 2008 Symposium No 4: Asteroseismology and Stellar Evolution