Related papers: The initial period function of late-type binary st…

We present constraints on the stellar initial mass function (IMF) in two ultra-faint dwarf (UFD) galaxies, Hercules and Leo IV, based on deep HST/ACS imaging. The Hercules and Leo IV galaxies are extremely low luminosity (M_V = -6.2, -5.5),…

We have analyzed nearly all images of the Taurus star-forming region at 3.6-24um that were obtained during the cryogenic mission of the Spitzer Space Telescope (46 deg^2) and have measured photometry for all known members of the region that…

I have undertaken a comprehensive statistical investigation of the ultracool dwarf companion distribution (spectral type M6 and later). Utilizing a Bayesian algorithm, I tested models of the companion distribution against data from an…

We have obtained the first measures of the mass accretion rates on stars of the Trapezium Cluster. They appear systematically lower than those of similar stars in the Taurus-Auriga association. Together with premature disk evaporation,…

The white dwarf mass distribution has been studied primarily at two extremes: objects that presumably evolved as single stars and members of close binaries that likely underwent substantial interaction. This work considers the intermediate…

Massive binary stars play a crucial role in many astrophysical fields. Investigating the statistical properties of massive binary stars is essential to trace the formation of massive stars and constrain the evolution of stellar populations.…

Binary F stars exhibit large brightness anomaly, which is defined here as the difference between the absolute magnitude from the uvby photometry and the actual absolute magnitude of the star. We have found that the anomaly inversely…

Monte Carlo simulations of the field substellar mass function (MF) are presented. Starting from various representations of the MF below 0.1 M$_{\sun}$ and the stellar birth rate, luminosity functions (LFs) and T$_{eff}$ distributions are…

Main sequence stars of spectral types F, G, and K with low to moderate activity levels exhibit a recognizable pattern known as the first ionization potential effect (FIP effect), where elements with lower first ionization potentials are…

(abridged) Our project endeavors to obtain a robust view of multiplicity among embedded Class I and Flat Spectrum protostars in a wide array of nearby molecular clouds to disentangle ``universal'' from cloud-dependent processes. We have…

We discuss a GC formation scenario in which the first generation (1G) of single asymptotic giant branch (AGB) stars and intermediate-mass close binaries (IMCBs) eject gas, from which the second generation (2G) of stars can be formed. The…

Few topics in astronomy initiate such vigorous discussion as whether or not the initial mass function (IMF) of stars is universal, or instead sensitive to the initial conditions of star formation. The distinction is of critical importance:…

We present a detailed analysis of the radial distribution of light-element multiple populations (LE-MPs) in the massive and dense globular cluster M80 based on the combination of UV and optical Hubble Space Telescope data. Surprisingly, we…

It is possible to extract, from the observations, distribution functions of the birth dynamical properties of a stellar population, and to also infer that these are quite invariant to the physical conditions of star formation. The most…

The white dwarf binary pathways survey is dedicated to studying the origin and evolution of binaries containing a white dwarf and an intermediate-mass secondary star of the spectral type A, F, G, or K (WD+AFGK). Here we present CPD-65\,264,…

Observations of young star-forming regions suggest that star clusters are born completely mass segregated. These initial conditions are, however, gradually lost as the star cluster evolves dynamically. For star clusters with single stars…

The zero-age main-sequence star AB Dor and the K dwarf component of the V471 Tau close binary have essentially identical rotation rates and spectral types. An analysis of their high resolution {\it Chandra} X-ray spectra reveals remarkably…

Pieces of empirical evidence suggest the existence of a period-age relation for long-period variables (LPVs). Yet, this property has hardly been studied on theoretical grounds thus far. We aim to examine the period-age relation using the…

The Upper Scorpius OB association is the nearest region of recent massive star formation and thus an important benchmark for investigations concerning stellar evolution and planet formation timescales. We present nine EBs in Upper Scorpius,…

We report on a near-infrared adaptive optics survey of a sample of 66 low-mass members of the pre-main sequence stellar cluster IC 348. We find 12 binary systems in the separation range 0.1-8.0 arcsec. An estimate of the number of faint…