Hipparcos and the Age of the Galactic Disc

Abstract

We have used the Hipparcos satellite colour magnitude diagram to determine the age of the Galactic disc. We first measure the metallicities of Hipparcos giants using DDO photometry (Høg & Flynn 1997). With accurate metallicities and distances we compute the minimum age of the Galactic disc as $11\pm 1$ Gyr using the colour of the reddest clump stars as a function of metallicity. In conjunction with the new ages derived for Globular Clusters using the same method (Jimenez et al 1996) we show that any delay between the formation of the halo and the disc was only 2-3 Gyr. Since disc galaxies may have been detected to redshifts as high as $z=3.15$ (Lu, Sargent and Barlow 1997) an age for our own Galactic disc of 11 Gyr favours open or non-zero $\Lambda$ cosmological models. We show that a Reimers mass-loss law is sufficient to explain the morphology of the red clump.

Submitted to MNRAS

Cited by in corpus (40)

• The propagation of uncertainties in stellar population synthesis modeling I: The relevance of uncertain aspects of stellar evolution and the IMF to the derived physical properties of galaxies
• On the Survival and Destruction of Spiral Galaxies in Clusters
• Distances, ages, and epoch of formation of globular clusters
• Population effects on the Red Giant Clump absolute magnitude, and distance determinations to nearby galaxies
• The White Dwarf Cooling Sequence of the Globular Cluster Messier 4
• Starcounts Redivivus. IV. Density Laws Through Photometric Parallaxes
• The Age of the Solar Neighbourhood
• Star Formation and Metallicity History of the SDSS galaxy survey: unlocking the fossil record
• A Planetary Mass Companion to the K0 Giant HD 17092
• The Helium abundance and Delta Y / Delta Z in Lower Main Sequence stars
• Millisecond Pulsar Velocities
• A Survey for Cool White Dwarfs and the age of the Galactic Disc
• Synthetic stellar populations: single stellar populations, stellar interior models and primordial proto-galaxies
• Stellar Populations at the Center of IC 1613
• An Intermittent Star Formation History in a 'Normal' Disk Galaxy: The Milky Way
• K dwarfs and the chemical evolution of the Solar cylinder
• Binary and Millisecond Pulsars at the New Millennium
• The Ccontribution of normal, dim and dwarf galaxies to the local luminosity density
• The Relative Age of the Thin and Thick Galactic Disks
• The Penn State - Torun Centre for Astronomy Planet Search stars. II. Lithium abundance analysis of the Red Giant Clump sample
• A Pan-STARRS1 View of the Bifurcated Sagittarius Stream
• Stellar Structure and Evolution: Deductions from Hipparcos
• Zeroing the Stellar Isochrone Scale: The Red Giant Clump Luminosity at Intermediate Metallicity
• The Penn State-Torun Centre for Astronomy Planet Search stars. I. Spectroscopic analysis of 348 red giants
• Stochastic angular momentum slews and flips and their effect on discs in galaxy formation models
• Local stellar formation history from the 40 pc white dwarf sample
• Orbital and physical parameters of eclipsing binaries from the ASAS catalogue -- II. Two spotted M < 1 M${}_{\odot }$ systems at different evolutionary stages
• Orbital and physical parameters of eclipsing binaries from the ASAS catalogue -- III. Two new low-mass systems with rapidly evolving spots
• Luminosity-metallicity relation for stars on the lower main sequence
• High resolution spectroscopic study of red clump stars in the Galaxy: iron group elements
• Impact of stellar population synthesis choices on forward modelling-based redshift distribution estimates
• The Galactic thick and thin disks: differences in evolution
• A HET search for planets around evolved stars
• The Luminosity Function of Magnitude and Proper-Motion Selected Samples. The case of White-Dwarfs
• The morphological evolution of galaxy satellites
• A New Ultracool White Dwarf Discovered in the SuperCOSMOS Sky Survey
• The Age of the Galactic Disk
• Euclid view of dusty star forming galaxies at z>~1.5 detected in wide area submillimetre surveys
• Neutron Star Birth Rates
• Clump stars in the Solar Neighbourhood