Notes on the disentangling of spectra I. Enhancement in precision

Context: The technique of disentangling has been applied to numerous high-precision studies of spectroscopic binaries and multiple stars. Although, its possibilities have not yet been fully understood and exploited. Aims: Theoretical background aspects of the method, its latest improvements and hints for its use in practice are explained in this series of papers. Methods: In this first paper of the series, we discuss spectral-resolution limitations due to a discrete representation of the observed spectra and introduce a new method how to achieve a precision higher than the step of input-data binning. Results: Based on this principle, the latest version of the KOREL code for Fourier disentangling achieves an increase in precision for an order of magnitude.Comment: 2 figure

Disentangling telluric lines in stellar spectra

The use of a method of spectra disentangling for telluric lines is explained in detail, with a particular emphasis on high-precision radial-velocity measurements for the search for extrasolar planets. New improvements to the method are introduced.Comment: Accepted for publication in Astronomy and Astrophysic

Notes on disentangling of spectra II. Intrinsic line-profile variability due to Cepheid pulsations

The determination of pulsation velocities from observed spectra of Cepheids is needed for the Baade-Wesselink calibration of these primary distance markers. The applicability of the Fourier-disentangling technique for the determination of pulsation velocities of Cepheids and other pulsating stars is studied. The KOREL-code was modified to enable fitting of free parameters of a prescribed line-profile broadening function corresponding to the radial pulsations of the stellar atmosphere. It was applied to spectra of delta Cep in the H-alpha region observed with the Ondrejov 2-m telescope. The telluric lines were removed using template-constrained disentangling, phase-locked variations of line-strengths were measured and the curves of pulsational velocities obtained for several spectral lines. It is shown that the amplitude and phase of the velocities and line-strength variations depend on the depth of line formation and the excitation potential. The disentangling of pulsations in the Cepheid spectra may be used for distance determination

V2368 Oph: An eclipsing and double-lined spectroscopic binary used as a photometric comparison star for U Oph

The A-type star HR 6412 = V2368 Oph was used by several investigators as a photometric comparison star for the known eclipsing binary U Oph but was found to be variable by three independent groups, including us. By analysing series of new spectral and photometric observations and a critical compilation of available radial velocities, we were able to find the correct period of light and radial-velocity variations and demonstrate that the object is an eclipsing and double-lined spectroscopic binary moving in a highly eccentric orbit. We derived a linear ephemeris T min.I = HJD (2454294.67 +/- 0.01) + (38.32712 +/- 0.00004)d x E and estimated preliminary basic physical properties of the binary. The dereddened UBV magnitudes and effective temperatures of the primary and secondary, based on our light- and velocity-curve solutions, led to distance estimates that agree with the Hipparcos distance within the errors. We find that the mass ratio must be close to one, but the limited number and wavelength range of our current spectra does not allow a truly precise determination of the binary masses. Nevertheless, our results show convincingly that both binary components are evolved away from the main sequence, which makes this system astrophysically very important. There are only a few similarly evolved A-type stars among known eclipsing binaries. Future systematic observations and careful analyses can provide very stringent tests for the stellar evolutionary theory.Comment: 10 pages, 7 figs, in press 2011 A&

Intake system for internal combustion engines

Bakalářská práce je zaměřena na sací systémy spalovacích motorů. Důraz je kladen hlavně na konstrukci a jednotlivé části sacích systémů. Část práce je také věnována různým druhům přeplňování motorů. Na závěr jsou jednotlivé části sacího systému popsány důkladněji.The bachelor’s thesis is focused on the internal combustion engine intake systems. Emphasis is placed mainly on the construction and the various parts of the intake systems. The part of the work is also devoted to the different types of supercharging. At the end, the individual parts of the intake system are described further.

Using Coaching Strategies to Build Caregiver Capacity

This research study investigated the use of coaching strategies to foster engagement and build the capacity of caregivers of very young children receiving early intervention services. This study was conducted as a result of concerns regarding low caregiver engagement and unanswered questions about acquisition of caregivers’ skills. Four participants were included in this study. The researcher collected qualitative and quantitative data to examine the impact of using a coaching model with caregiver-participants. Interview data, engagement ratings and a research journal were used to collect engagement and caregiver capacity data. As a result of data collection and analysis, the author reported that participants demonstrated an average engagement rating of 4.75 out of 5 by the end of the research period. Related to caregiver capacity, interview data evidenced skills indicative of improved self-efficacy. Finally, interview data evidenced circumstances in which caregivers, who like themselves were caring for very young children with special needs, were not connected to other caregivers

Optical Spectroscopic Observations of Cyg X-1=HDE 226868

We present the results of the spectroscopic observations of HDE 226868, the optical counterpart to the black hole X-ray binary Cyg X-1, from 2001 to 2006. We analyze the variabilities of the two components in the complex H$\alpha$ line: one P-Cygni shaped component which follows the motion of the supergiant and another emission component moving with an antiphase orbital motion relative to the supergiant, which is attributed to a focused-stellar wind. The results of KOREL disentangling of our spectra indicate that the focused stellar wind is responsible for the major part of the variability of the H$\alpha$ emission line. The emission of the supergiant component had a small difference between the low/hard and high/soft states, while the focused wind component became strong in the low/hard state and weak in the high/soft state. The wind is nearly undisturbed by the X-ray photoionization during the low/hard state. However, during the high/soft state, the X-rays from the compact object could decelerate the line-driven wind and result in a high mass accretion rate, due to the effect of the X-ray photoionization. The X-ray illuminating could also change the temperature profile of the stellar wind and increase its temperature, and thus decrease the H$\alpha$ emissivity of the wind, which could explain the H$\alpha$ variabilities of Cyg X-1 during different X-ray states.Comment: 26 pages, 7 figures, 3 tables, AJ in pres