相关论文: Chromospherically young, kinematically old stars
The rotation rate, level of magnetic activity and surface lithium abundance are age-dependent quantities in stars of about a solar mass and below. The physical reasons for the evolution of these phenomena are qualitatively understood, but…
Determining the sequence of events in the formation of stars and planetary systems and their time-scales is essential for understanding those processes, yet establishing ages is fundamentally difficult because we lack direct indicators. In…
Nearby late-type stars are excellent targets to look for young objects in stellar associations and moving groups. The study of these groups goes back more than one century ago however, their origin is still misunderstood. Although their…
We present an analysis of the lithium abundances in late spectral type binaries of different ages. They belong to several open clusters (Pleiades, Hyades and M67), as well as to Chromospherically Active Binary Systems (CABS). All these…
Young stars in the solar neighborhood serve as nearby probes of stellar evolution and represent promising targets to directly image self-luminous giant planets. We have carried out an all-sky search for late-type ($\approx$K7$-$M5) stars…
In the last three decades several hundred nearby members of young stellar moving groups (MGs) have been identified, but there has been less systematic effort to quantify or characterise young stars that do not belong to previously…
Chromospheric activity has been calibrated and widely used as an age indicator. However, it has been suggested that the viability of this age indicator is, in the best case, limited to stars younger than about 1.5 Gyr. I aim to define the…
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,…
Nearby late-type stars are excellent targets for seeking young objects in stellar associations and moving groups. The origin of these structures is still misunderstood, and lists of moving group members often change with time and also from…
Results of photometric surveys have brought to light the existence of a population of giant planets orbiting their host stars even closer than the hot Jupiters (HJ), with orbital periods below 3 days. The reason why radial velocity surveys…
We present a study of the lithium abundances of a sample of evolved components of Chromospherically Active Binary Systems. We show that a significant part of them have lithium excesses, independently of their mass and evolutionary stage.…
Stellar magnetic activity decays over the main-sequence life of cool stars due to the stellar spin-down driven by magnetic braking. The evolution of chromospheric emission is well-studied for younger stars, but difficulties in determining…
In this paper we investigate how the chemical and kinematic properties of stars vary as a function of age. Using data from a variety of photometric, astrometric and spectroscopic surveys, we calculate the ages, phase space information and…
Young stars form in associations, meaning that young stellar associations provide an ideal environment to measure the age of a nominally coeval population. Isochrone fitting, which is the typical method for measuring the age of a coeval…
Eclipsing binary stars provide highly accurate measurements of the fundamental physical properties of stars. They therefore serve as stringent tests of the predictions of evolutionary models upon which most stellar age determinations are…
This paper describes our study of the astrophysics of individual components in close pre-main-sequence binaries. We observed both stars in 17 systems, located in 4 nearby star forming regions, using low-resolution (R=760), infrared…
The magnetic activity of the Sun becomes stronger and weaker over roughly an 11 year cycle, modulating the radiation and charged particle environment experienced by the Earth as "space weather". Decades of observations from the Mount Wilson…
Gravitational-wave detections are enabling measurements of the rate of coalescences of binaries composed of two compact objects -- neutron stars and/or black holes. The coalescence rate of binaries containing neutron stars is further…
Once mixed in the ambient galactic plane stellar population, young stars are virtually indiscernible because neither their global photometric properties nor the presence of nearby gas can help to disentangle them from older ones.…
I discuss observations of two traditional age indicators, chromospheric activity and kinematics, in late-M and L dwarfs near the hydrogen-burning limit. The frequency and strength of chromospheric activity disappears rapidly as a function…