The white dwarf in dwarf nova SDSS J080434.20+510349.2: Entering the instability strip?

SDSS J080434.20+510349.2 is the WZ type binary that displayed rare outburst in 2006 (Pavlenko et al., 2007). During the long-lasting tail of the late stage of the outburst binary shown the two-humped or four-humped profile of the orbital light modulation. The amplitude of orbital light curve decreased while the mean brightness decreased, more over that occurred $\sim$ 10 times faster during the fast outburst decline in respect to the late quiet state of slow outburst fading. There were no white dwarf pulsations detected neither 1 - 1.5 months prior to the outburst nor in 1.5 - 2 months after the 2006 outburst in this system. However the strong non-radial pulsations with period 12.6 minutes and mean amplitude of 0.05^m were first detected in V band with 2.6-m Shajn mirror telescope of the Crimean astrophysical observatory in ~ 8 months after the outburst. The evolution of pulsations over two years in 2006 - 2008 is considered. It is supposed that pulsations first appeared when the cooling white dwarf (after the outburst) entered the instability strip although the possibility of temporary lack of pulsations at some occasions also could not be excluded.Comment: Submitted to Proceedings of 16th European White Dwarf Workshop (EUROWD08

Теоретико-методичні аспекти актуальності професійної підготовки майбутніх фахівців з публічного управління

Theoretical and methodological substantiation of the relevance of professional training of future specialists in public administration, characterized the structure of professional competence of future specialists in public administration in the system triad of qualities in the components - personal as the ability to perform process-technological functions, personalized-intellectual, systematizing professional special oriented academic components of competence, business in the specialty, which is mutually consistent with the psychological and physiological characteristics of the individual and personified by the classification characteristics of their own ability to work in the criteria; the definition of "public administration specialist" is formulated in the author's interpretation.Key words: professional training, public administration specialist, professional competence, theoretical and methodological aspects, structure, relevance.Здійснено теоретико-методичне обґрунтування актуальності професійної підготовки майбутніх фахівців з публічного управління, схарактеризовано структуру професійної компетентності майбутніх фахівців з публічного управління у системній тріаді якостей в компонентах – особистісному як спроможностей здійснювати процесно-технологічні функції, персоніфіковано-інтелектуальному, що систематизує професійні спеціальні та функціонально-орієнтовані академічні складові компетентності, діловому щодо фаху, який взаємо узгоджується з психолого-фізіологічними характеристиками особистості та персоніфікований за класифікаційними ознаками власного потенціалу працездатності у критеріях; сформульовано у авторському трактуванні дефініцію «фахівець з публічного управління». Ключові слова: професійна підготовка, фахівець з публічного управління, професійна компетентність, теоретико-методичні аспекти, структура, актуальність

Vsini-s for late-type stars from spectral synthesis in K-band region

We analyse medium-resolution spectra (R\sim 18000) of 19 late type dwarfs in order to determine vsini-s using synthetic rather than observational template spectra. For this purpose observational data around 2.2 $\mu$m of stars with spectral classes from G8V to M9.5V were modelled. We find that the Na I (2.2062 and 2.2090 $\mu$m) and $^{12}$CO 2-0 band features are modelled well enough to use for vsini determination without the need for a suitable observational template spectra. Within the limit of the resolution of our spectra, we use synthetic spectra templates to derive vsini values consistent with those derived in the optical regime using observed templates. We quantify the errors in our vsini determination due to incorrect choice of model parameters \Teff, log $g$, $v_{\rm micro}$, [Fe/H] or FWHM and show that they are typically less than 10 per cent. We note that the spectral resolution of our data(\sim 16 km/s) limited this study to relatively fast rotators and that resolutions of 60000 will required to access most late-type dwarfs.Comment: 8 pages, 4 figures, 3 tables, accepted to the MNRA

A catalogue of bright (K <9) M dwarfs

Using the Position and Proper Motion Extended-L (PPMXL) catalogue, we have used optical and near-infrared colour cuts together with a reduced proper motion cut to find bright M dwarfs for future exoplanet transit studies. PPMXL's low proper motion uncertainties allow us to probe down to smaller proper motions than previous similar studies. We have combined unique objects found with this method to that of previous work to produce 8479 K <9 M dwarfs. Low-resolution spectroscopy was obtained of a sample of the objects found using this selection method to gain statistics on their spectral type and physical properties. Results show a spectral-type range of K7-M4V. This catalogue is the most complete collection of K <9 M dwarfs currently available and is made available here.Peer reviewe

Metallicity and effective temperature of the secondary of RS Oph

The recurrent nova RS Oph undergoes nova eruptions every ~ 10-20years as a result of thermonuclear runaway on the surface of a white dwarf close to the Chandrasekhar limit. Both the progress of the eruption, and its aftermath, depend on the (poorly known) composition of the red giant in the RS Oph system. Our aim is to understand better the effect of the giant secondary on the recurrent nova eruption. Synthetic spectra were computed for a grid of M-giant model atmospheres having a range of effective temperatures 3200 < Teff < 4400 K, gravities 0 < log g < 1 and abundances -4 <[Fe/H] < 0.5, and fit to infrared spectra of RS Oph as it returned to quiescence after its 2006 eruption. We have modelled the infrared spectrum in the range 1.4-2.5 micron to determine metallicity and effective temperature of the red giant. We find Teff = 4100 +/- 100 K, log g = 0.0 +/- 0.5, [Fe/H] = 0.0 +/- 0.5, [C/H] = -0.8 +/- 0.2, [N/H] = +0.6 +/- 0.3 in the atmosphere of the secondary, and demonstrate that that inclusion of some dust `veiling' in the spectra cannot improve our fits.Comment: 6 pages, 5 figs, 1 table, to appear in A&

Boron in Very Metal-Poor Stars

We have observed the B I 2497 A line to derive the boron abundances of two very metal-poor stars selected to help in tracing the origin and evolution of this element in the early Galaxy: BD +23 3130 and HD 84937. The observations were conducted using the Goddard High Resolution Spectrograph on board the Hubble Space Telescope. A very detailed abundance analysis via spectral synthesis has been carried out for these two stars, as well as for two other metal-poor objects with published spectra, using both Kurucz and OSMARCS model photospheres, and taking into account consistently the NLTE effects on the line formation. We have also re-assessed all published boron abundances of old disk and halo unevolved stars. Our analysis shows that the combination of high effective temperature (Teff > 6000 K, for which boron is mainly ionized) and low metallicity ([Fe/H]<-1) makes it difficult to obtain accurate estimates of boron abundances from the B I 2497 A line. This is the case of HD 84937 and three other published objects (including two stars with [Fe/H] ~ -3), for which only upper limits can be established. BD +23 3130, with [Fe/H] ~ -2.9 and logN(B)_NLTE=0.05+/-0.30, appears then as the most metal-poor star for which a firm measurement of the boron abundance presently exists. The evolution of the boron abundance with metallicity that emerges from the seven remaining stars with Teff < 6000 K and [Fe/H]<-1, for which beryllium abundances were derived using the same stellar parameters, shows a linear increase with a slope ~ 1. Furthermore, the B/Be ratio found is constant at a value ~ 20 for stars in the range -3<[Fe/H]<-1. These results point to spallation reactions of ambient protons and alpha particles with energetic particles enriched in CNO as the origin of boron and beryllium in halo stars.Comment: 38 pages, 11 Encapsulated Postscript figures (included), uses aaspp4.sty. Accepted for publication in The Astrophysical Journal. The preprint is also available at: http://www.iac.es/publicaciones/preprints.htm

Infrared spectroscopy of the merger candidate KIC 9832227

Context. It has been predicted that the object KIC 9832227 – a contact binary star – will undergo a merger in 2022.2±0.7.We describe the near infrared spectrum of this object as an impetus to obtain pre-merger data. Aims. We aim to characterise (i) the nature of the individual components of the binary and (ii) the likely circumbinary environment, so that the merger – if and when it occurs – can be interpreted in an informed manner. Methods. We use infrared spectroscopy in the wavelength range 0.7 μm–2.5 μm, to which we fit model atmospheres to represent the individual stars. We use the binary ephemeris to determine the orbital phase at the time of observation. Results. We find that the infrared spectrum is best fitted by a single component having effective temperature 5 920 K, log [g] = 4.1 and solar metallicity, consistent with the fact that the system was observed at conjunction. Conclusions. The strength of the infrared H lines is consistent with a high value of log g, and the strength of the Ca ii triplet indicates the presence of a chromosphere, as might be expected from rapid stellar rotation. The He i absorption we observe likely arises in He excited by coronal activity in a circumstellar envelope, suggesting that the weakness of the Ca ii triplet is also likely chromospheric in origin