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Multiplicity is one of the most fundamental observable properties of massive O-type stars and offers a promising way to discriminate between massive star formation theories. Nevertheless, companions at separations between 1 and 100 mas…
We present a new sample of 84 large angular size radio galaxies selected from the NRAO VLA Sky Survey. Radio sources with declination above +60 degrees, total flux density greater than 100 mJy at 1.4 GHz and angular size larger than 4…
This paper reports estimated stellar parameters of 1,153 Kepler red giant branch stars determined with asteroseismic modeling. We use radial-mode oscillation frequencies, gravity-mode period spacings, Gaia luminosities, and spectroscopic…
We present HD-TESS, a catalog of 1,709 bright ($V\sim3-10$) red giants from the Henry Draper (HD) Catalog with asteroseismic measurements based on photometry from NASA's Transiting Exoplanet Survey Satellite (TESS). Using light curves…
The central area of the Sculptor dwarf galaxy was surveyed for variable stars as a side-program of the OGLE project. Light curves in the V band were obtained for 226 RR Lyr stars and for 3 anomalous cepheids. One previously unknown…
We report long-term scintillation observations of 18 pulsars in the DM range 3-35 pc cm^{-3} carried out during 1993-1995 using the Ooty Radio Telescope at 327 MHz. These observations were made with the aim of studying refractive effects in…
We use one-dimensional hydrodynamic calculations combined with synthetic stellar population models of the Magellanic Clouds to study the onset of self-excited pulsation in luminous red giants. By comparing the results with OGLE observations…
The objective of this work is to determine what fraction of red-giant (RG) stars shows photometric rotational modulation, and understand its origin. One of the underlying questions is the role of close binarity in this population, standing…
Hot Jupiters form an enigmatic class of object with yet unclear formation pathways. Determination of their occurrence rates as function orbit, planet and stellar mass, and system age, can be an important ingredient for understanding how…
We have studied the magnetic field of about 50 active and non-active single G-K-type red giants by means of spectropolarimetry with Narval and ESPaDOnS. 30 giants have been significantly Zeeman-detected. A close study of the 17 giants with…
In the present paper, we aim to determine the kinematical properties, velocity ellipsoid, and Oort constants using a sample of halo red giants. The study is based mainly on the space and radial velocities of about 1583 red giant stars…
Massive stars undergo fundamental-mode and first-overtone radial pulsations with periods of 100-1000 days as Red Supergiants (RSGs). At large amplitudes, these pulsations substantially modify the outer envelope's density structure…
The rapidly oscillating Ap (roAp) stars exhibit pulsational photometric and/or radial velocity variations on time scales of several minutes, which are essential to test current pulsation models as well as our assumptions of atmospheric…
Context. Certain periodic variations of radial velocities (RV) of wobbling giants originate from exoplanets. Indeed, a number of exoplanets have been discovered around giant stars. Aims. The purpose of our study is to find low-amplitude and…
Strongly irradiated giant planets are observed to have radii larger than thermal evolution models predict. Although these inflated planets have been known for over fifteen years, it is unclear whether their inflation is caused by deposition…
The length of the asteroseismic timeseries obtained from the Kepler satellite analysed here span 19 months. Kepler provides the longest continuous timeseries currently available, which calls for a study of the influence of the increased…
In this review, I reflect on four decades of my experience in linking astronomy research and education by supervising variable-star research projects by undergraduates, and by outstanding senior high school students. I describe the…
Of the approximately 350 extrasolar planets currently known, of order 10% orbit evolved stars with radii R >~ 2.5 R_sun. These planets are of particular interest because they tend to orbit more massive hosts, and have been subjected to…
The Penn State/Toru\'n Centre for Astronomy Search for Planets Around Evolved Stars is a high-precision radial velocity (RV) survey aiming at planets detection around giant stars. It is based on observations obtained with the 9.2 m…
Precise and accurate mass and radius measurements of evolved stars are crucial to calibrating stellar models. Stars in detached eclipsing binaries (EBs) are excellent potential calibrators because their stellar parameters can be measured…