White dwarf period tables – I. Pulsators with hydrogen-dominated atmospheres

We collected all known white dwarf pulsators with hydrogen-dominated atmospheres and list their main photometric and atmospheric parameters together with their pulsation periods and amplitudes observed at different epochs. Exploring the pulsating white dwarf related literature with the systematic use of the SIMBAD and the NASA’s Astrophysics Data System (ADS) databases. Four tables listing seven ZZ Ceti stars in detached white dwarf plus main-sequence binaries, seven extremely low-mass DA pulsators, three hot DAVs and 180 ZZ Ceti stars

KIC 2831097. A short orbital-period candidate RR Lyrae binary

KIC 2831097 was discovered to be a first-overtone RR Lyrae pulsator based on 4-year Kepler photometry (Sódor et al. 2017, MNRAS, 465, L1). The data show strong, 0.1 d amplitude systematic phase variations that can be explained by light travel-time effect caused by an about 2-year period orbital motion in a binary system, superimposed on a linear pulsation-period decrease. To verify the binary hypothesis, several well-timed radial-velocity observations will be sufficient

KIC 9533489: a genuine γ Doradus – δ Scuti Kepler hybrid pulsator with transit events

Context Several hundred candidate hybrid pulsators of type A–F have been identified from space-based observations. Their large number allows both statistical analyses and detailed investigations of individual stars. This offers the opportunity to study the full interior of the genuine hybrids, in which both low-radial-order p- and high-order g-modes are self-excited at the same time. However, a few other physical processes can also be responsible for the observed hybrid nature, related to binarity or to surface inhomogeneities. The finding that most δ Scuti stars also show long-period light variations represents a real challenge for theory. Aims We aim at determining the pulsation frequencies of KIC 9533489, to search for regular patterns and spacings among them, and to investigate the stability of the frequencies and the amplitudes. An additional goal is to study the serendipitously detected transit events: is KIC 9533489 the host star? What are the limitations on the physical parameters of the involved bodies? Methods Fourier analysis of all the available Kepler light curves. Investigation of the frequency and period spacings. Determination of the stellar physical parameters from spectroscopic observations. Modelling of the transit events. Results The Fourier analysis of the Kepler light curves revealed 55 significant frequencies clustered into two groups, which are separated by a gap between 15 and 27 d −1. The light variations are dominated by the beating of two dominant frequencies located at around 4 d −1 . The amplitudes of these two frequencies show a monotonic long-term trend. The frequency spacing analysis revealed two possibilities: the pulsator is either a highly inclined moderate rotator (v ≈ 70 km s −1 , i > 70 ◦ ) or a fast rotator (v ≈ 200 km s −1 ) with i ≈ 20 ◦ . The transit analysis disclosed that the transit events, which occur with a ≈ 197 d period may be caused by a 1.6 R_Jup body orbiting a fainter star, which would be spatially coincident with KIC 9533489

MOST light-curve analysis of the gamma Dor pulsator HR 8799, showing resonances and amplitude variations

Context The central star of the HR 8799 system is a gamma Doradus-type pulsator. The system harbours four planetary-mass companions detected by direct imaging, and is a good solar system analogue. The masses of the companions are not known accurately, because the estimation depends strongly on the age of the system, which is also not known with sufficient accuracy. Asteroseismic studies of the star might help to better constrain the age of HR\,8799. We organized an extensive photometric and multi-site spectroscopic observing campaign for studying the pulsations of the central star. Aims The aim of the present study is to investigate the pulsation properties of HR 8799 in detail via the ultra-precise 47-d-long nearly continuous photometry obtained with the MOST space telescope, and to find as many independent pulsation modes as possible, which is the prerequisite of an asteroseismic age determination. Methods We carried out Fourier analysis of the wide-band photometric time series. Results e find that resonance and sudden amplitude changes characterize the pulsation of HR 8799. The dominant frequency is always at f_1 = 1.978 d^-1. Many multiples of one ninth of the dominant frequency appear in the Fourier spectrum of the MOST data: n/9 f_1, where n = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 13, 14, 17, 18\}. Our analysis also reveals that many of these peaks show strong amplitude decrease and phase variations even on the 47-d time-scale. The dependencies between the pulsation frequencies of HR 8799 make the planned subsequent asteroseismic analysis rather difficult. We point out some resemblance between the light curve of HR 8799 and the modulated pulsation light curves of Blazhko RR Lyrae stars

Impacts of surface model generation approaches on raytracing-based solar potential estimation in urban areas

Raytracing-based methods are widely used for quantifying irradiation on building surfaces. Urban 3D surface models are necessary input for raytracing simulations, which can be generated from open-source point cloud data with the help of surface reconstruction algorithms. In research and engineering practice, various algorithms are being used for this purpose; each leading to different mesh topologies and corresponding performance. This paper compares the impacts of four different reconstruction algorithms by investigating their performance using DAYSIM raytracing simulations. The analysis is carried out for five configurations with various urban morphologies. Results show that the reconstructed models consistently underestimate the shading influence due to geometrical shrinkages that emerge from the various model generation procedures. The explicit algorithms, with Generic Delaunay a notable example, have better performance with less embedded error than the implicit algorithms in both daily and annual simulations. Results also show that diffuse irradiance is responsible for larger contributions to the overall error than direct components. This effect becomes more prominent when modeling reflected irradiation in urban environments. Additionally, the work shows that solar elevation and shading geometry types also affect the error magnitude. The paper concludes by providing reconstruction algorithm selection criteria for photovoltaic practitioners and urban energy planners

KIC 2831097 - A 2-year orbital-period RR Lyrae binary candidate

We report the discovery of a new Kepler first-overtone RR Lyrae pulsator, KIC 2831097. The pulsation shows large, 0.1 d amplitude, systematic phase variations that can be interpreted as light travel-time effect caused by orbital motion in a binary system, superimposed on a linear pulsation-period decrease. The assumed eccentric (e=0.47) orbit with the period of approximately 2 yr is the shortest among the non-eclipsing RR Lyrae binary candidates. The binary model gives a lowest estimate for the mass of the companion of 8.4 M_Sun, that places it among black hole candidates. Beside the first-overtone pulsation, numerous additional non-radial pulsation frequencies were also identified. We detected an ~47-d Blazhko-like irregular light-curve modulation

Az extracelluláris mátrix komponensek tumorinvázióban betöltött szerepe intrakraniális daganatokban. The role of extracellular matrix components in the invasion of intracranial malignancies.

A primer agydaganatok gyakorlatilag mindig bekövetkezõ lokális kiújulásának egyik fõ oka a daganatsejtek környezõ agyállományt érintõ infiltrációja. Ez az invazív tulajdonság teszi általában lehetetlenné a teljes mûtéti tumoreltávolítást és a fokális sugárkezelés effektivitását is jelentõsen csökkenti. Érdekes módon azonban egyéb szerveink szintén anaplasztikus tumorainak nem ritka agyi áttétei sokkal kisebb mértékû peritumorális beszûrõdést mutatnak, így radikális eltávolításuk és sugárkezelésük (akár sztereotaxiás pontbesugárzással is) igen jó eredménnyel jár. A két daganattípus kezelési effektivitásában tapasztalt jelentõs különbség magyarázata leginkább a jelentõsen eltérõ mértékû környezeti invázióban keresendõ. Nem véletlen tehát, hogy a különbözõ agydaganatok infiltrációs képességének molekuláris szintû kutatására régóta komoly erõfeszítéseket tettek, és az antiinvazív készítmények onkoterápiában való alkalmazására is számos kísérlet történt. Ezeknek a kutatási eredményeknek az összefoglalása található az alábbi közleményben, mely az agydaganatok inváziójának sejt- és molekuláris szintû folyamatai mellett a potenciális onkoterápiás lehetõségeket is ismerteti. The usual local recurrence of primary brain tumors is mainly due to the infiltration of adjacent brain parenchyma by the glioma cells. This invasive feature of the tumors makes total surgical excision impossible and also decreases the efficacy of focal radiotherapy. Interestingly, intracerebral metastases originating from many anaplastic tumors of other organs perform very moderate peritumoral infiltration, therefore radical resection can be routinely achieved and focal irradiation, even stereotactic radiotherapy, provides good tumor control. Differences in the effectiveness of treatment between the two tumor types derive from the remarkably different extent of peritumoral infiltration. Thus significant molecular biological research has been dealing with the infiltrative activity of various brain tumors and many attempts were made to develop anti-invasive drugs for oncotherapy. This review summarizes the results of these studies, describing cellular and molecular events of brain tumor invasion and according potential oncotherapeutic possibilities

Investigation of the binary fraction among candidate A-F type hybrid stars detected by Kepler

We are currently monitoring up to 40 Kepler candidate δ Scuti-γ Doradus (resp. γ Doradus-δ Scuti) hybrid stars in radial velocity in order to identify the physical cause behind the low frequencies observed in the periodograms based on the ultra-high accuracy Kepler space photometry. The presence of low frequency variability in unevolved or slightly evolved oscillating A/F-type stars can generally be explained in three ways: either 1) the star is an (un)detected binary or multiple system, or 2) the star is a g-mode pulsator (i.e. a genuine hybrid), or 3) the star's atmosphere displays an asymmetric intensity distribution (caused by spots, i.e. chemical anomalies, or by (very) high rotation), which is detected through rotational modulation. Our targets were selected from the globally characterized variable A/F-type stars of the Kepler mission [7]. We observe each star at least 4 times unevenly spread over a time lapse up to 2 months with the HERMES spectrograph [6]. In the case of composite, multiple-lined spectra, these observations also provide the atmospheric properties of each component. Our principal goal is to estimate the fraction of short-period, spectroscopic systems in the sample