Search Publications

Conditions for the formation of anomalous tail of comet

Safarov, Abduljalol G.; Ibadinov, Khursand I.

The time and velocity of ejection of dust particles of anomalous tails from cometary nuclei are determined. It is revealed that some comets cause the formation of an anomalous tail is the collision of their comet nucleus with other bodies of the Solar System. An investigation of the formation conditions of the anomalous tail shows that the dust ej…

Photometric and spectroscopic investigation of nine Cepheids in the Cassiopeia constellation

Handler, G.; Zejda, M.; Paunzen, E. +3 more

We present new multicolor BVRI photometry and low-resolution spectroscopy of 9 fundamental mode Cepheids in the Cassiopeia constellation. Observations were carried out during the 2017/2018 observing season. We investigated each particular light curve in detail using Fourier decomposition techniques which we compare with the Cepheids from the OGLE …

Theoretical Prediction of Asymmetric Instability of Drift Kinetic Alfven Waves in Anisotropic Plasmas

Ilie, Raluca; Chen, Lunjin; Bashir, M. F.

The asymmetric instability of drift kinetic Alfvén waves (DKAWs) is analyzed to study the interplay between the density inhomogeneity and the temperature anisotropy, including the wave-particle interaction and finite ion Larmor radius effects. The asymmetric behavior arises due to the opposite diamagnetic drifts of electrons and ions and quantifie…

SAPREMO: a simplified algorithm for predicting detections of electromagnetic transients in surveys

Stratta, G.; Branchesi, M.; Ciolfi, R. +3 more

The multiwavelength detection of GW170817 has inaugurated multimessenger astronomy. The next step consists in interpreting observations coming from population of gravitational wave sources. We introduce SAPREMO, a tool aimed at predicting the number of electromagnetic signals characterized by a specific light curve and spectrum, expected in a part…

Two temperate sub-Neptunes transiting the star EPIC 212737443

Livingston, John H.; Dominik, Martin; Hernández, Jesús +11 more

We report the validation of a new planetary system around the K3 star EPIC 212737443 using a combination of K2 photometry, follow-up high-resolution imaging and spectroscopy. The system consists of two sub-Neptune sized transiting planets with radii of 2.6R_⊕ and 2.7R_⊕, with orbital periods of 13.6 and 65.5 d, equilibrium temp…

Astronomical distance scales

Mignard, François

This article is an overview of the determination of astronomical distances from a metrological standpoint. Distances are considered from the Solar System (planetary distances) to extragalactic distances, with a special emphasis on the fundamental step of the trigonometric stellar distances and the giant leap recently experienced in this field than…

Validating the C I 5052.17 Å/Mg II 4481 Å Equivalent Width Ratio as a Diagnostic for F-type Lambda Boo Stars

Cheng, Kwang-Ping; Tarbell, Erik S.; Giacinto, Anthony J. +5 more

The Lambda Boo-type stars are chemically peculiar stars with deficiencies of iron-peak elements but near-solar C, N, O, and S abundances. Since the prototype Lambda Boötis was first reported as peculiar, this group has been expanded from a small group of early A-type stars to a larger group of late B to early F-type dwarfs. Although a detailed abu…

A Hint of Three-section Halo As Seen from the APOGEE DR14

Zhao, G.; Chen, Y. Q.; Xue, X. X. +4 more

Based on the [M/H] versus [Mg/Fe] diagram and distances from APOGEE data release 14, we compare the spatial distributions, the l - V _los diagram, and the abundance gradients between high-[Mg/Fe] and low-[Mg/Fe] sequences. The two sequences are clearly shown at 5< | Z| < 10 {kpc} in the metallicity range of -1.6 < [M/H] < -0.…

XMM-Newton spectrum of the magnetar CXOU J171405.7-381031

Bamba, Aya; Watanabe, Haruka; Shibata, Shinpei +1 more

We observe the magnetar CXOU J171405.7-381031 with XMM-Newton and obtain the most reliable X-ray spectral parameters for this magnetar. After removing the flux from the surrounding supernova remnant CTB 37B, the radiation of CXOU J171405.7-381031 is best described by a two-component model, consisting of a blackbody and power law. We obtain a black…

TYC 3637-1152-1 - A high amplitude δ Scuti star with peculiar pulsational properties

Meingast, Stefan; Sulzenauer, Nikolaus; Pribulla, Theodor +16 more

In some δ Scuti stars, only one or two radial modes are excited (usually the fundamental mode and/or first overtone mode) and the observed peak-to-peak amplitudes exceed 0.3 mag (V). These stars are known as High Amplitude Delta Scuti (HADS) variables.

We here present a detailed photometric and spectroscopic analysis of the HADS star TYC 3637…