Related papers: DY/DZ from fine structure in the Main Sequence bas…

(Abridged) A procedure is suggested to explore the value of F = alpha^2/mu, where mu = m_e/m_p is the electron-to-proton mass ratio, and alpha is the fine-structure constant. The fundamental physical constants, which are measured in…

This contribution describes the difficult task of inferring the IMF from local star-count data, by discussing the mass-luminosity relation, unresolved binary, triple and quadruple systems, abundance and age spreads and Galactic structure,…

Observed variations in the slope of the initial stellar mass function are shown to be consistent with a model in which the protostellar gas is randomly sampled from hierarchical clouds at a rate proportional to the square root of the local…

We perform a search for faint, common proper motion companions of Hipparcos stars using the recently published LSPM-north catalog of stars with proper motion mu>0.15 arcsec/yr. Our survey uncovers a total of 521 systems with angular…

The triple stellar system delta Vel (composed of two A-type and one F-type main sequence stars) is particularly interesting as it contains one of the nearest and brightest eclipsing binaries. It therefore presents a unique opportunity to…

We use the deep ground-based optical photometry of the Lyman Break Galaxy (LBG) Survey to derive robust measurements of the faint-end slope (alpha) of the UV LF at redshifts 1.9<z<3.4. Our sample includes >2000 spectroscopic redshifts and…

Systematic variations of the IMF in early-type galaxies, and their connection with possible drivers such as velocity dispersion or metallicity, have been much debated in recent years. Strong lensing over galaxy scales combined with…

Recent papers have found that the inferred slope of the high-mass ($>1.5$ M$_\odot$) IMF for field stars in the solar vicinity has a larger value ($\sim 1.7-2.1$) than the slopes ($\sim 1.2-1.7$; Salpeter= 1.35) inferred from numerous…

The stellar initial mass function is of great significance for the study of star formation and galactic structure. Observations indicate that the IMF follows a power-law form. This work derived that when the expected number of stars formed…

Hipparcos parallaxes and proper motions have made it possible to construct Hertzsprung-Russell (HR) diagrams of nearby clusters with unprecedented accuracy. The standard deviation of high fidelity non-binary non-variable stars about a model…

We constrain the evolution of the galaxy stellar mass function from 2 < z < 5 for galaxies with stellar masses as low as 10^5 Msun by combining star formation histories of Milky Way satellite galaxies derived from deep Hubble Space…

Precise radial velocity measurements (delta v/c ~ 10^{-7}) of FeII lines in damped Ly-alpha systems from very high quality VLT/UVES spectra of quasars HE0515-4414 and Q1101-264 are used to probe cosmological time dependence of the fine…

We have used new parallax measurements, obtained by the Hipparcos satellite, of fifteen nearby, metal-poor stars to re-define the subdwarf main-sequence. All of these stars have parallaxes determined to an accuracy of at least 12 %.…

The High-Z Supernova Search is an international collaboration to discover and monitor type Ia supernovae (SN Ia) at $z > 0.2$ with the aim of measuring cosmic deceleration and global curvature. Our collaboration has pursued a basic…

With recent advances in modelling stars using high-precision asteroseismology, the systematic effects associated with our assumptions of stellar helium abundance ($Y$) and the mixing-length theory parameter ($\alpha_\mathrm{MLT}$) are…

Intermediate mass Pre-main sequence stars (1.5 $M_{\odot}< M < 5M_{\odot}$) cross the instability strip on their way to the main sequence. They are therefore expected to be pulsating in a similar way as the $\delta$ Scuti stars. In this…

(Abridged) Many-multiplet (MM) method applied to three inhomogeneous samples of Keck/HIRES quasar absorption spectra gives a shift in the value of the fine-structure constant of Delta alpha/alpha = (-5.4+/-1.2) 10^{-6} in the redshift range…

We use the Illustris Simulations to gain insight into the build-up of the outer, low-surface brightness regions which surround galaxies. We characterize the stellar haloes by means of the logarithmic slope of the spherically-averaged…

We derive the fundamental parameters (temperature and luminosity) of 107 619 Hipparcos stars and place these stars on a true Hertzsprung-Russell diagram. This is achieved by comparing BT-Settl model atmospheres to spectral energy…

We constrain the slope of the star formation rate ($\log\Psi$) to stellar mass ($\log\mathrm{M_{\star}}$) relation down to $\log(\mathrm{M_{\star}/M_{\odot}})=8.4$ ($\log(\mathrm{M_{\star}/M_{\odot}})=9.2$) at $z=0.5$ ($z=2.5$) with a…