Related papers: Why are there Seven Sisters?
Compact elliptical galaxies form a rare class of stellar system (~30 presently known) characterized by high stellar densities and small sizes and often harboring metal-rich stars. They were thought to form through tidal stripping of massive…
Implications of the recently discovered systematic abundance difference between the Sun and two collections of `solar twins' are discussed. The differences can be understood as an imprint on the abundances of the solar convection zone…
There has been a long standing debate about the existence of maya constellations, but there are several sources of evidences that favour this hypothesis: mural paintings, stelae and codex. In this work, we have recovered and compiled…
Essentially everything of astronomical interest is either part of a galaxy, or from a galaxy, or otherwise relevant to the origin or evolution of galaxies. Diverse examples are that the isotropic composition of meteorites provides clues to…
Circumbinary planets (CBPs) are planets that orbit around both stars of a binary system. This chapter traces the history of research on CBPs and provides an overview over the current knowledge about CBPs and their detection methods. After…
Binaries have played a crucial role many times in the history of modern astronomy and are doing so again in the rapidly evolving exploration of the Kuiper Belt. The large fraction of transneptunian objects that are binary or multiple, 48…
The name "Ultra-Compact Dwarf Galaxy" (UCD) was invented for a new type of astronomical object that has been discovered in cores of nearby galaxy clusters a decade ago. UCDs resemble globular clusters, but are up to 100 times more massive…
The population statistics of binary stars are an important output of star formation models. However populations of wide binaries evolve over time due to interactions within a system's birth environment and the unfolding of wide,…
The Kepler mission has provided high quality light curves for more than 2000 eclipsing binaries. Tertiary companions to these binaries can be detected if they transit one or both stars in the binary or if they perturb the binary enough to…
Asteroids formed in a dynamically quiescent disk but their orbits became gravitationally stirred enough by Jupiter to lead to high-speed collisions. As a result, many dozen large asteroids have been disrupted by impacts over the age of the…
Abundance anomalies have been determined at the surface of many field and open cluster A and F dwarfs. These abundance anomalies are most likely caused by microscopic diffusion at work within the stable envelopes of A stars. However…
Young (125 Myr), populous ($>$1000 members), and relatively nearby, the Pleiades has provided an anchor for stellar angular momentum models for both younger and older stars. We used K2 to explore the distribution of rotation periods in the…
In the outskirts of nearby spiral galaxies, star formation is observed in extremely low gas surface densities. Star formation in these regions, where the interstellar medium is dominated by diffuse atomic hydrogen, is difficult to explain…
The origin of the Martian moons Deimos and Phobos is controversial. One hypothesis for their origin is that they are captured asteroids, but the mechanism requires an extremely dense martian atmosphere, and the mechanism by which an…
We point out an intriguing relation between the masses of the transiting planets and their orbital periods. For the six currently known transiting planets, the data are consistent with a decreasing linear relation. The other known…
Exoplanetary systems are found not only among single stars, but also binaries of widely varying parameters. Binaries with separations of 100--1000 au are prevalent in the Solar neighborhood; at these separations planet formation around a…
As a relatively young and bright population and the archetype of standard candles, classical Cepheids are an ideal population on which to trace the non-axisymmetric structure in the young stellar disk to large distances. We used the new…
It is well established that many galaxies, like our Milky Way, exhibit spiral patterns. The entire galactic disc rotates about the galactic centre with different speeds; higher closer to the centre, lower at greater distances - that is,…
Oppenheimer et al. (1997) discovered two M5 dwarfs in the Pleiades with nearly primordial lithium. These stars are not low enough in mass to represent the leading edge of the lithium depletion boundary at Pleiades age (~125 Myr). A possible…
Whether the spiral structure of galaxies is trailing or leading has been a subject of debate. We present a new spin parity catalog of 146 spiral galaxies that lists the following three pieces of information: whether the spiral structure…