相关论文: M Subdwarfs: The Population II Luminosity Function

The radial number density and flattening of the Milky Way's stellar halo is measured with $\mathrm{5351}$ metal-poor ([Fe/H]$<-1$) K giants from LAMOST DR3, using a nonparametric method which is model independent and largely avoids the…

We study the age and metallicity distribution function (MDF) of metal-poor stars in the Milky Way halo as a function of galactocentric radius by combining N-body simulations and semi-analytical methods. We find that the oldest stars…

We analyze 166 spheroid subdwarfs $(6.5<M_V<14.5)$ found in 53 fields observed with the Wide Field Camera on the {\it Hubble Space Telescope}. The fields cover 221 square arcmin over a wide range of directions. The spheroid luminosity…

We present a non-parametric, empirically based, model for associating galaxy luminosities with halo/subhalo masses, based on a self-consistent treatment of subhalo mass loss and the subhalo mass function. We find that, at high mass, the…

Recent observations suggest the existence of a white dwarf population in the Galactic halo, while others suggest that deuterium has been astrated in systems at high redshift and low metallicity. We propose that these observations could be…

The universality of the halo mass function is investigated in the context of dark energy cosmologies. This widely used approximation assumes that the mass function can be expressed as a function of the matter density omega_m and the rms…

We study a sample of 257 Galactic disk M dwarfs (8<M_V<18.5) found in images obtained using HST. These include 192 stars in 22 fields imaged with the repaired WFC2 with mean limiting mag I=23.7 and 65 stars in 162 fields imaged with the…

We present an analysis of the metallicity distribution functions of fields projected along the minor axis for a sample of inclined spiral galaxies in order to search for evidence of the presence of multiple stellar populations. In all…

We examine a sample of 223 F, G and early K metal-poor subdwarfs ([m/H]<-1) with high proper motions ($\mu > 0.2"/$ year) at the distances of up to 250 pc from the Sun. By means of our own speckle interferometric observations conducted on…

A previous study (Nissen & Schuster 2010) of 94 dwarf stars with -1.6 < [Fe/H] < -0.4 has revealed the existence of two distinct halo populations with a systematic difference in [alpha/Fe] at a given metallicity. In continuation of that…

We use a high resolution $\Lambda$CDM numerical simulation to calculate the mass function of dark matter haloes down to the scale of dwarf galaxies, back to a redshift of fifteen, in a 50 $h^{-1}$Mpc volume containing 80 million particles.…

The Pristine survey uses narrow-band photometry to derive precise metallicities down to the extremely metal-poor regime ([Fe/H] < -3), and currently consists of over 4 million FGK-type stars over a sky area of $\sim 2~500\, \mathrm{deg}^2$.…

We present deep V & I WFPC2 photometry in two fields in the M31 halo 32' and 50' from the center of M31 along the SE minor axis at the locations of the M31 GCs G302 and G312 respectively. The M31 halo LFs are not consistent with a single…

We present measurements of the luminosity and mass functions of low-mass stars constructed from a catalog of matched Sloan Digital Sky Survey (SDSS) and 2 Micron All Sky Survey (2MASS) detections. This photometric catalog contains more than…

Applying the revised M subdwarf classification criteria discussed in Paper I to LAMOST DR7, combining the M subdwarf sample from Savcheva et al, a new M subdwarf sample was constructed for further study. The atmospheric parameters for each…

As an investigation of the origin of ``$\alpha$-poor'' halo stars, we analyze kinematic and abundance data for 73 intermediate metallicity stars ($-1 >$ [Fe/H] $\geq -2$) selected from Paper I of this series. We find evidence for a…

We present new infrared photometry for 61 halo and disk stars around the stellar/substellar boundary. These data are combined with available optical photometry and astrometric data to produce color--color and absolute magnitude--color…

White dwarfs are the fossils left by the evolution of low-and intermediate-mass stars, and have very long evolutionary timescales. This allows us to use them to explore the properties of old populations, like the Galactic halo. We present a…

We present a high precision photometric view of the stellar populations in the outer halo of M31, using data taken with the Hubble Space Telescope Advanced Camera for Surveys (HST/ACS). We analyse the field populations adjacent to 11…

I report on recent results from observations of stars with metallicities [Fe/H] <= -2.0. These include a substantial new sample of objects with high-resolution observations obtained as part of a follow-up of the HK Survey, The Hamburg/ESO…