ESO Top 10 Astronomical Discoveries

1. Accelerating Universe
   Two independent research teams have shown that the expansion of the Universe is accelerating — based on observations of exploding stars with astronomical telescopes at La Silla.
   Science papers:
   Riess,A. et.al., 1998, AJ116 1009,
   Schmidt, B. et.al., 1998, ApJ 507 46,
   Perlmutter, S. et al, 1998, Nature,
   Tonry, J.L. et al, 2003, ApJ (Telbib),
   Knop, R.A. et al, 2003, ApJ (Telbib),
   Riess, A. et al, 2004, ApJ (Telbib),
   Astier, P. et al, 2006, A&A (Telbib)
   Read more on the ESO Press Release eso9861
   
   
2. First image of an exoplanet
   The VLT has obtained the first-ever image of a planet outside our Solar System. The 5-Jupiter-mass planet orbits a failed star — a brown dwarf — at a distance of 55 times the mean Earth-Sun distance.
   Science paper:
   Chauvin et al. 2004 (Telbib)
   Read more on the ESO Press Release eso0428
   
   
3. Stars orbiting the Milky Way black hole
   Several of ESO’s flagship telescopes were used in a 16-year long study to obtain the most detailed view ever of the surroundings of the monster lurking at the heart of our galaxy — a supermassive black hole.
   Science papers:
   Schödel 2003 (Telbib),
   Gillessen 2009 (Telbib)
   Read more on the ESO Press Release eso0226 and eso0846
   
   
4. The gamma-ray burst–supernova connection
   ESO telescopes have provided definitive proof that long gamma-ray bursts are linked with the ultimate explosion of massive stars, solving a long-time puzzle.
   Science papers:
   Hjort 2003 (Telbib),
   Galama T.J. et al, 1998, Nature
   Read more on the ESO Press Release eso0318
   
   
5. The motion of stars in the Milky Way
   After more than 1000 nights of observations at La Silla, spread over 15 years, astronomers have determined the motions of more than 14 000 Sun-like stars residing in the neighbourhood of the Sun, showing that our home galaxy has led a much more turbulent and chaotic life than previously assumed.
   Science paper:
   Nördstrom 2004
   Read more on the ESO Press Release eso0411
   
   
6. Oldest star known in the Milky Way
   Using ESO's VLT, astronomers have measured the age of the oldest star known in our galaxy, the Milky Way. At 13.2 billion years old, the star was born in the earliest era of star formation in the Universe.
   Science paper:
   Pasquini 2004 (Telbib)
   Read more on the ESO Press Release eso0425
   
   
7. Merging neutron star—gamma-ray burst connection
   A telescope at La Silla was able to observe the visible light from a short gamma-ray burst for the first time, showing that this family of objects most likely originated from the violent collision of two merging neutron stars.
   Science papers:
   Hjorth 2005, Nature,
   Hjorth 2005 ApJL (Telbib),
   Pedersen 2005 (Telbib)
   Read more on the ESO Press Release eso0533
   
   
8. Cosmic temperature independently measured
   The VLT has detected carbon monoxide molecules in a galaxy located almost 11 billion light-years away for the first time, a feat that had remained elusive for 25 years. This has allowed astronomers to obtain the most precise measurement of the cosmic temperature at such a remote epoch.
   Science paper:
   Srianand, R. et al, 2000, Nature (Telbib)
   Read more on the ESO Press Release eso0043
   
   
9. Most distant object measured
   The Very Large Telescope has obtained the spectral signature of the earliest, most distant known object in the Universe, seen only about 600 million years after the Big Bang.
   Science paper:
   Tanvir et al. 2009 (Telbib)
   Read more on the ESO Press Release eso0917
   
   
10. Lightest exoplanet found
    The HARPS spectrograph helped astronomers discover a system containing the lightest exoplanet — only about twice the mass of our Earth — as well as a planet located within the habitable zone, where liquid water oceans could exist.
    Science paper:
    Mayor et al. 2009 A&A (Telbib)
    Read more on ESO Press Release eso0915