Related papers: Testing Theoretical Evolutionary Models with AB Do…

We present a catalogue of RIZ photometry over an area of 0.855 square degrees, centred on NGC 2547. The survey is substantially complete to limits of R_c=21.5, I_c=19.5, Z=19.5. We use the catalogue to define NGC 2547 candidates with masses…

An Early Enrichment Population (EEP) has been theorized to produce the observed intracluster medium (ICM) metallicity of galaxy clusters. This population likely existed at high redshifts (z$\sim$10), relics of which we posit exist today as…

We present a statistical comparison of the mass ratio distribution of companions, as observed in different multiplicity surveys, to the most recent estimate of the single object mass function (Bochanski et al. 2010). The main goal of our…

We present the results of deep and high-resolution (FWHM ~ 0".35) JHK NIR observations with the Subaru telescope, to search for very low mass young stellar objects (YSOs) in the W3 Main star-forming region. The NIR survey covers an area of…

Juvenile ultracool dwarfs are late spectral type objects (later than ~M6) with ages between 10 Myr and several 100 Myr. Their age-related properties lie intermediate between very low mass objects in nearby star-forming regions (ages 1-5…

We determine an absolute calibration of stellar mass-to-light ratios for the densest \simeq 3% of early-type galaxies in the local universe (redshift z\simeq 0.08) from SDSS DR7. This sample of \sim 4000 galaxies has, assuming a Chabrier…

The origin of the stellar Initial Mass Function (IMF) and how it may vary with galactic environment is a matter of debate. Certain star formation theories involve a close connection between the IMF and the Core Mass Function (CMF) so it is…

(Abridged) Low-mass stars have been recognised as promising targets in the search for rocky, small planets with the potential of supporting life. Doppler search programmes using high-resolution spectrographs like HARPS or HARPS-N are…

Upon its discovery in 2006, the young L7.5 companion to the solar analog HD 203030 was found to be unusual in being $\approx$200 K cooler than older late-L dwarfs. HD 203030B offered the first clear indication that the effective temperature…

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),…

The substellar initial mass function (IMF) and the formation mechanisms of brown dwarfs (BDs) remain key open questions in star formation theory. IMF characterization in a large number of star-forming regions (SFRs) is essential for…

We present preliminary trigonometric parallaxes of 184 late-T and Y dwarfs using observations from Spitzer (143), USNO (18), NTT (14), and UKIRT (9). To complete the 20-pc census of $\ge$T6 dwarfs, we combine these measurements with…

Eta Chamaeleontis is a unique young (~9 Myr) association with 18 systems concentrated in a radius of ~35 arcmin, i.e. 1pc at the cluster distance of 97pc. No other members have been found up to 1.5 degrees from the cluster centre. The…

Using recently established empirical calibrations for the impact of chromospheric activity on the radii, effective temperatures, and estimated masses of active low-mass stars and brown dwarfs, we reassess the shape of the initial mass…

We present optical and near-infrared adaptive optics (AO) imaging and spectroscopy of 13 ultracool (>M6) companions to late-type stars (K7-M4.5), most of which have recently been identified as candidate members of nearby young moving groups…

We undertake a systematic analysis of the early (< 0.5 Myr) evolution of clustering and the stellar initial mass function in turbulent fragmentation simulations. These large scale simulations for the first time offer the opportunity for a…

As part of a comprehensive effort to characterize the nearest stars, the CHIRON echelle spectrograph on the CTIO/SMARTS 1.5m telescope is being used to acquire high resolution (R = 80000) spectra of K dwarfs within 50 parsecs. This paper…

A common proper motion survey of M dwarf stars within 8 pc of the Sun reveals no new stellar or brown dwarf companions at wide separations (~100-1400 AU). This survey tests whether the brown dwarf ``desert'' extends to large separations…

We present new evidence for a problem with cooling rates predicted by substellar evolutionary models that implies model-derived masses in the literature for brown dwarfs and directly imaged planets may be too high. Based on our dynamical…

We present the results of a photometric and spectroscopic study of the white dwarf candidate members of the intermediate age open clusters NGC3532 and NGC2287. Of the nine objects investigated, it is determined that six are probable members…