Related papers: The Decay of Stellar Dynamos and X-ray Activity
Chandra images of the elliptical galaxy NGC4261 have revealed an anisotropy in the spatial distribution of the off-nuclear X-ray sources, interpreted by Zezas et al. as evidence of an association with a young stellar population. Our…
Three different M31 disk fields, spanning a range of stellar populations, were observed by Chandra. We report the X-ray point source luminosity function (LF) of each region, and the LF of M31's globular clusters, and compare these with each…
Emission from X-ray binaries (XRBs) is a major component of the total X-ray luminosity of normal galaxies, so X-ray studies of high redshift galaxies allow us to probe the formation and evolution of X-ray binaries on very long timescales.…
The diagram of indices of coronal and chromospheric activity allowed us to reveal stars where solar-type activity appears and regular cycles are forming. Using new consideration of a relation between coronal activity and the rotation rate,…
We investigate the spatial distribution of X-ray emitting plasma in a sample of young Orion Nebula Cluster stars by modulation of their X-ray light-curves due to stellar rotation. The study, part of the Chandra Orion Ultradeep Project…
Throughout an activity cycle, magnetic structures rise to the stellar surface, evolve and decay. Tracing their evolution on a stellar corona allows us to characterize the X-ray cycles. However, directly mapping magnetic structures is…
Recent Chandra observations of nearby galaxies have revealed a number of ultraluminous X-ray sources (ULXs) with super-Eddington luminosities, away from the central regions of non-active galaxies. The nature of these sources is still…
This chapter provides an overview of the magnetic activity of the Sun and stars, discussing its underlying physical origin, manifestations, and fundamental role in exoplanet studies. It begins with a summary of the Sun's magnetic activity…
Studies of stellar populations, understood to mean collections of stars with common spatial, kinematic, chemical, and/or age distributions, have been reinvigorated during the last decade by the advent of large-area sky surveys such as SDSS,…
X-ray emission has played a major role in the recent identification of several groups of young, nearby stars. The ROSAT All-Sky Survey (RASS) is due to its spatial completeness an important tool for discovering stellar associations and…
Background diffuse X-ray emission is contributed in large part by the emission of point sources not individually resolved. While this is established since decades for the contribution of quasars to the diffuse emission above 1 keV energies,…
The interstellar medium of galaxies, with temperatures reaching several million degrees, provides a pivotal perspective for understanding the physical and chemical properties of star formation, galactic evolution, and their associated…
If the stellar halos of disk galaxies are built up from the disruption of dwarf galaxies, models predict highly structured variations in the stellar populations within these halos. We test this prediction by studying the ratio of blue…
We present the first search for spinning dust emission from a sample of 34 Galactic cold cores, performed using the CARMA interferometer. For each of our cores we use photometric data from the Herschel Space Observatory to constrain N_{H},…
We have cross-correlated X-ray catalogs derived from archival Chandra ACIS observations with a Sloan Digital Sky Survey (SDSS) Data Release 2 (DR2) galaxy catalog to form a sample of 42 serendipitously X-ray detected galaxies over the…
The coronal activity-rotation relationship is considered to be a proxy for the underlying stellar dynamo responsible for magnetic activity in solar and late-type stars. While this has been studied in considerable detail for…
Accurate estimates of the absorption of X-rays by interstellar gas and dust are of crucial importance for the analysis and interpretation of almost all astronomical soft X-ray observations. However, the present X-ray absorption data…
The X-ray emission from flares on cool (i.e. spectral-type F-M) stars is indicative of very energetic, transient phenomena, associated with energy release via magnetic reconnection. We present a uniform, large-scale survey of X-ray flare…
The inner ~200 pc region of the Milky Way contains a nuclear stellar disc and a nuclear star cluster that are embedded in the larger Galactic bar. These stellar systems overlap spatially, which makes it challenging to separate stars that…
The existing and upcoming multiwavelength data from the Galactic Center suggest a comparative study in order to propose or rule out possible models which would explain the observations. In this paper we consider the X-ray synchrotron and…