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Planet-Star Interactions with Precise Transit Timing. I. The Refined Orbital Decay Rate for WASP-12 b and Initial Constraints for HAT-P-23 b, KELT-1 b, KELT-16 b, WASP-33 b and WASP-103 b

Maciejewski G., Fernández M., Aceituno F., Martín-Ruiz S., Ohlert J., Dimitrov D., Szyszka K., von Essen C., Mugrauer M., Bischoff R., Michel K.-U., Mallonn M., Stangret M., Moździerski D.

Acta Astronomica

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2018

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Vol. 68, No. 4

371--401

EN

Theoretical calculations and some indirect observations show that massive exoplanets on tight orbits must decay due to tidal dissipation within their host stars. This orbital evolution could be observationally accessible through precise transit timing over a course of decades. The rate of planetary in-spiraling may not only help us to understand some aspects of evolution of planetary systems, but also can be used as a probe of the stellar internal structure. In this paper we present results of transit timing campaigns organized for a carefully selected sample of the Northern hemisphere hot Jupiter-like planets which were found to be the best candidates for detecting planet-star tidal interactions. Among them, there is the WASP-12 system which is the best candidate for possessing an in-falling giant exoplanet. Our new observations support the scenario of orbital decay of WASP-12 b and allow us to refine its rate. The derived tidal quality parameter of the host star Q'*=(1.82±0.32)×105 is in agreement with theoretical predictions for subgiant stars. For the remaining systems – HAT-P-23, KELT-1, KELT-16, WASP-33, and WASP-103 – our transit timing data reveal no deviations from the constant-period models, hence constraints on the individual rates of orbital decay were placed. The tidal quality parameters of host stars in at least four systems – HAT-P-23, KELT-1, WASP-33, and WASP-103 – were found to be greater than the value reported for WASP-12. This is in line with the finding that those hosts are main sequence stars, for which efficiency of tidal dissipation is predicted to be relatively weak.

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New Transit Observations for HAT-P-30 b, HAT-P-37 b, TrES-5 b, WASP-28 b, WASP-36 b and WASP-39 b

Maciejewski G., Dimitrov D., Mancini L., Southworth J., Ciceri S., D'Ago G., Bruni I., Raetz St., Nowak G., Ohlert J., Puchalski D., Saral G., Derman E., Petrucci R., Jofre E., Seeliger M., Henning T.

Acta Astronomica

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2016

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Vol. 66, No. 1

55--74

EN

We present new transit light curves for planets in six extrasolar planetary systems. They were acquired with 0.4-2.2 m telescopes located in west Asia, Europe, and South America. When combined with literature data, they allowed us to redetermine system parameters in a homogeneous way. Our results for individual systems are in agreement with values reported in previous studies. We refined transit ephemerides and reduced uncertainties of orbital periods by a factor between 2 and 7. No sign of any variations in transit times was detected for the planets studied.

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Biomass of the xerothermic oak ecosystem on a site of community importance, BG0001040 "Zapadna stara planina i predbalkan", Bulgaria

Lyubenova M., Dimitrova V., Georgieva N., Dimitrov D.

Drewno : prace naukowe, doniesienia, komunikaty

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2014

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vol. 57, nr 192

89--106

EN

The belowground and aboveground biomass was estimated for the tree story, sprouts and seedling regeneration in a representative Quercus frainetto – Quercus cerris ecosystem on “Zapadna Stara planina i Predbalkan”, a Site of Community Importance (SCI). The biomass was measured by destructive sampling (on sample or “model trees” representing three calculated density classes for each species and cut at the stump) of leaves, annual and perennial branches, wood, bark and root components. The belowground (root) biomass was also calculated from a subsample. The data obtained were compared to the results of previous studies and the values on the Bazilevich and Rodin [1971] scale. The ecological status of the forest ecosystem studied and its functional efficiency are discussed based on the study results and specific climate data.

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Revisiting Parameters for the WASP-1 Planetary System

Maciejewski G., Ohlert J., Dimitrov D., Puchalski D., Nedoroščík J., Vaňko M., Marka C., Baar S., Raetz St., Seeliger M., Neuhäuser R.

Acta Astronomica

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2014

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Vol. 64, No. 1

27--43

EN

We present thirteen new transit light curves for the WASP-1b exoplanet. Observations were acquired with 0.5 m-1.2 m telescopes between 2007 and 2013. Our homogeneous analysis, which also includes the literature data, results in determining precise system parameters. New values are in agreement with those reported in previous studies. Transit times follow a linear ephemeris with no sign of any transit time variations. This finding is in line with the paradigm that Jupiter-like planets on tight orbits are devoid of close planetary companions. Key words: planetary systems - Stars: individual: WASP-1 - Planets and satellites: individual: WASP-1b

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Chemometric assessment of river water during a flood event

Simeonova P., Lovchinov V., Dimitrov D., Radulov I.

Ecological Chemistry and Engineering. A

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2008

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Vol. 15, nr 3

187-198

EN

Heavy metals, arsenic, and physicochemical basic parameters were analyzed during a spring flood 2005. Daily samples were taken at a sampling site in the middle part of the river Elbe. The site is part of the network of the International Commission for the Protection of the Elbe (IKSEIMKOL). Cluster analysis, principal components analysis (PCA) and source apportionment were used to assess the flood-dependent matter transport. It was found that most of the metal components ale in relation to suspended matter transport and can be explained by a sediment washout factor. In contrast, uranium, chloride, and dissolved organic matter were part of the water discharge factor. A third factor contains nickel, manganese, and zinc, reflecting a separate influence of former mining activities in the catchment area.

PL

Podczas wiosennej powodzi w 2005 roku analizowano w wodzie rzeki stężenie metali ciężkich, arsenu i parametry fizykochemiczne wody. Próbki pobierano w środkowej części biegu rzeki Laby. Ten teren jest częścią większego obszaru będącego pod ochroną Międzynarodowej Komisji Ochrony Laby (IKSE/MKOL). Zastosowano analizę klastrów, analizę czynników głównych (PCA) i udziału źródeł pochodzenia zanieczyszczeń do oceny wpływu powodzi na transport zanieczyszczeń wody. Stwierdzono, że największe stężenia metali pochodzą z materii zawieszonej, pochodzącej z wymywania osadów dennych. Natomiast uran, chlorki i rozpuszczone substancje organiczne pochodziły ze zrzutów ścieków do rzeki. Obecność w wodzie niklu, manganu i cynku wskazywała na wpływ, już zaprzestanej, działalności górniczej w tym rejonie dorzecza.

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Quality assessment of the Yantra River water monitoring data

Simeonova P., Lovchinov V., Dimitrov D., Radulov I.

Chemia i Inżynieria Ekologiczna

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2007

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Vol. 14, nr 7

693-705

EN

The present study deals with the river water quality assessment for the Yantra River catchment, Bulgaria. The application of multivariate statistical methods like cluster analysis, principal components analysis and time-series analysis makes it possible to detect different sampling sites patterns along the river steam related to the urban or rural activities in the area and to identify latent factors responsible for the monitoring data structure. Additionally, tendencies and seasonal patterns in the data are discussed. An interesting point in the study is that the water quality assessment is performed using short-term and long-term observation data, which allows a better evaluation of the ecological situation along the river stream.

PL

Obecne badania dotyczą oceny jakości wody w zlewni rzeki Jantra, Bułgaria. Zastosowanie różnych metod statystycznych, takich jak: analiza skupień, analiza głównych składowych i analiza serii czasowych, umożliwiło znalezienie zróżnicowań w strukturze danych z punktów próbkowania wzdłuż biegu rzeki w zależności od obecności miast i wsi oraz identyfikację ukrytych czynników wpływających na strukturę danych pomiarowych. Dodatkowo omówiono tendencje i sezonowe zmiany otrzymanych wyników. Oceniono jakość wody, dokonując obserwacji długo i krótkoterminowych pozwalających na lepszą ocenę sytuacji ekologicznej wzdłuż biegu rzeki.

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Geodynamic investigations on the territory of Bulgaria. Investigations of the Krupnik-Kresna region related to the 1904 earthquake

Milev G., Dimitrov D., Glavcheva R., Shanov S., Matova M., Vassileva K.

Reports on Geodesy

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2000

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z. 4/49

10-256