Assessing statistical significance of periodogram peaks

The least-squares (or Lomb-Scargle) periodogram is a powerful tool which is used routinely in many branches of astronomy to search for periodicities in observational data. The problem of assessing statistical significance of candidate periodicities for different periodograms is considered. Based on results in extreme value theory, improved analytic estimations of false alarm probabilities are given. They include an upper limit to the false alarm probability (or a lower limit to the significance). These estimations are tested numerically in order to establish regions of their practical applicability.Comment: 7 pages, 6 figures, 1 table; To be published in MNRA

Wavelet analysis algorithm for bi- and trivariate statistical distributions

Рассматривается задача поиска статистически значимых структур в распределении каких-либо астрономических объектов. Для этого используется метод вейвлет-анализа в дву- или трехмерном пространстве параметров. Алгоритм двумерного анализа полностью завершен и опубликован в виде открытого C++ кода стабильной версии, тогда как трехмерный алгоритм находится на экспериментальной стадии.We consider the task of detecting statistically significant patterns in a distribution of some astronomical objects. For this goal we use the wavelet analysis method in bi- or trivariate parametric space. The bivariate analysis algorithm is finished and released as an open-source C++ code of a stable version, while the trivariate algorithm is at an experimental stage.Работа выполнена при поддержке Министерства науки и высшего образования РФ, проект 075-15-2020-780 (N13.1902.21.0039)

Benchmarking the power of amateur observatories for TTV exoplanets detection

This document is the Accepted Manuscript version of the following article: Roman v. Baluev, et al, ‘Benchmarking the power of amateur observatories for TTV exoplanets detection’, Monthly Notices of the Royal Astronomical Society, Vol. 450(3): 3101-3113, first published online 9 May 2015. The version of record is available at doi: https://doi.org/10.1093/mnras/stv788 © 2015 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society.We perform an analysis of ~80000 photometric measurements for the following 10 stars hosting transiting planets: WASP-2, -4, -5, -52, Kelt-1, CoRoT-2, XO-2, TrES-1, HD 189733, GJ 436. Our analysis includes mainly transit lightcurves from the Exoplanet Transit Database, public photometry from the literature, and some proprietary photometry privately supplied by other authors. Half of these lightcurves were obtained by amateurs. From this photometry we derive 306 transit timing measurements, as well as improved planetary transit parameters. Additionally, for 6 of these 10 stars we present a set of radial velocity measurements obtained from the spectra stored in the HARPS, HARPS-N, and SOPHIE archives using the HARPS-TERRA pipeline. Our analysis of these TTV and RV data did not reveal significant hints of additional orbiting bodies in almost all of the cases. In the WASP-4 case, we found hints of marginally significant TTV signals having amplitude 10-20 sec, although their parameters are model-dependent and uncertain, while radial velocities did not reveal statistically significant Doppler signals.Peer reviewe

Fast MOID Computation Algorithm with Error Control

We present a new fast algorithm to compute the minimum orbital intersection distance (MOID).Представлен новый быстрый алгоритм вычисления параметра MOID (расстояния между орбитами).Работа выполнена при поддержке гранта РНФ 19-72-10023

Search for Inhomogeneities of Brightness Profiles of Secondary Eclipses in the Infrared Range Using Correlation Noise SA Spitzer Modeling

Построена модель коррелированного шума в полосе 3.6 мкм космического телескопа Spitzer/IRAC, используемая для цели поиска неоднородностей инфракрасного профиля яркости экзопланеты HD209458b. Учет шума выполнялся при помощи метода максимального правдоподобия в модели гауссового процесса. Выявлена сложная природа красного шума, содержащего две компоненты с характерным временем затухания порядка 10 с и 5 мин. Получена глубина вторичного затмения 0.094±0.013 % и отклонение центра затмения на 3.1 ± 3.4 мин.A correlated noise model in the 3.6 μm band of the Spitzer/IRAC space telescope is constructed for the purpose of searching for inhomogeneities in the infrared brightness profile of the exoplanet HD209458b. The noise was treated using the maximum likelihood method in the Gaussian process model. The complex nature of red noise, which contains two components with characteristic decay times of the order of 10 seconds and 5 minutes, is revealed. We obtained a secondary eclipse depth of 0.094 ± 0.013 % and an eclipse center deviation of 3.1 ± 3.4 minutes

Doppler confirmation of TESS planet candidate TOI1408.01: grazing transit and likely eccentric orbit

We report an independent Doppler confirmation of the TESS planet candidate orbiting an F-type main sequence star TOI-1408 located 140 pc away. We present a set of radial velocities obtained with a high-resolution fiber-optic spectrograph FFOREST mounted at the SAO RAS 6-m telescope (BTA-6). Our self-consistent analysis of these Doppler data and TESS photometry suggests a grazing transit such that the planet obscures its host star by only a portion of the visible disc. Because of this degeneracy, the radius of TOI-1408.01 appears ill-determined with lower limit about $\sim$1 R$_{\rm Jup}$, significantly larger than in the current TESS solution. We also derive the planet mass of $1.69\pm0.20$~$M_{\rm Jup}$ and the orbital period $\sim4.425$ days, thus making this object a typical hot Jupiter, but with a significant orbital eccentricity of $0.259\pm0.026$. Our solution may suggest the planet is likely to experience a high tidal eccentricity migration at the stage of intense orbital rounding, or may indicate possible presence of other unseen companions in the system, yet to be detected.Comment: 5 pages, 3 figure