54 HST orbits allocated to eLARS

In order to celebrate a substantial allocation of time on the Hubble Space Telescope (HST) in cycle 21, the LARS project invited all of OKC for a drink on wednesday 12 june. This time, eLARS, the extension of the LARS project was awarded another 54 spacecraft orbits. In total the LARS project has so far been awarded 110 orbits, and is the biggest Swedish led project on HST ever.

The aim of the LARS project is to improve our understanding of how the Lyman alpha emission line is formed and transported out of galaxies. This is vital since Lyman alpha is the most accessible and most commonly used spectral probe of the distant universe. LARS will make extremely detailed studies of Ly alpha emission from 42 galaxies in the nearby universe, obtaining a physical resolution more than 2 orders of magnitude better than achievable at high redshift. One of the results that have emerged so far is that galaxies appear systematically larger when seen in Lyman alpha than in the continuum or in other recombination lines such as Halpha, a consequence of Lyman alpha photons resonantly scattering on neutral hydrogen atoms.

Image of the first galaxy in the LARS sample (Mkn259). In blue, Lyman alpha is shown, in red H-alpha and in green/yellow the Ultra Violet continuum. The size of the image corresponds to 15 by 15 kpc (approx 50000x50000 light years)

– Göran Östlin – ostlin@astro.su.se

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