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On the mass-to-light ratio of the local Galactic disc and the optical luminosity of the Galaxy
We measure the volume luminosity density and surface luminosity density generated by the Galactic disc, using accurate data on the local luminosity function and the vertical structure of the disc.
The local density of matter mapped by hipparcos
We determine the velocity distribution and space density of a volume-complete sample of A and F stars, using parallaxes and proper motions from the Hipparcos satellite. We use these data to solve for
The colours of the sun
We compile a sample of Sun-like stars with accurate effective temperatures, metallicities and colours (from the ultraviolet to the near-infrared). A crucial improvement is that the effective
Distance to NGC 253 based on the planetary nebula luminosity function
We identify a sample of 14 planetary nebulae in the nearby starburst disc galaxy NGC 253, using broad- and narrow-band imaging. A simple model of the stellar and dust layers in the galaxy shows that
M dwarfs: effective temperatures, radii and metallicities
We empirically determine effective temperatures and bolometric luminosities for a large sample of nearby M dwarfs, for which high accuracy optical and infrared photometry is available. We introduce a
The inner halo of M 87: a first direct view of the red-giant population
An unusually deep (V, I) imaging dataset for the Virgo supergiant M 87 with the Hubble Space Telescope ACS successfully resolves its brightest red-giant stars, reaching M I (lim) = ―2.5. After
The local surface density of disc matter mapped by Hipparcos
We determine the surface density of matter in the disc of the Galaxy at the solar position using K giant stars. The local space density and luminosity function of the giants is determined using
The host galaxy of a fast radio burst
The discovery of a fast radio burst is reported and the identification of a fading radio transient lasting ~6 days after the event, which is used to identify the host galaxy and measure the galaxy’s redshift, which provides a direct measurement of the cosmic density of ionized baryons in the intergalactic medium.
A single fast radio burst localized to a massive galaxy at cosmological distance
Interferometric localization of the single-pulse FRB 180924 to a position 4 kiloparsecs from the center of a luminous galaxy at redshift 0.3214 indicates that some FRBs are clean probes of the baryonic component of the cosmic web.
The helium abundance and ΔY/ΔZ in lower main-sequence stars
We use nearby K dwarf stars to measure the helium-to-metal enrichment ratio ΔY/ΔZ, a diagnostic of the chemical history of the solar neighbourhood. Our sample of K dwarfs has homogeneously determined