Free Astronomy Magazine September-October 2015

SPACE CHRONICLES scara, Italy) has now used the FEROS in- strument on the MPG/ESO 2.2-metre telescope at the La Silla Observatory, as well the PUCHE- ROS spectrograph on the ESO 0.5- metre telescope at the Observatory of the Pontificia Uni- versidad Catolica de Chile in Santa Martina near San- tiago, to study the nova Nova Cen- tauri 2013 (V1369 Centauri). These comparatively small telesco- pes, equipped with suitable spectro- graphs, are powerful tools for this kind of research. Even in the era of extremely large telescopes smaller telescopes dedicated to specific tasks can remain very valuable. The star exploded in the southern skies close to the bright star Beta Centauri in December 2013 and was the bright- est nova so far this century — easily visible to the naked eye. The very detailed new data revealed the clear signature of lithium being expelled at two million kilometres per hour from the nova. This high ve- locity, from the nova towards the Earth, means that the wavelength of the line in the absorption in the spec- trum due to the presence of lithium is significantly shifted towards the blue end of the spectrum. This is the first detection of the element eject- ed from a nova system to date. Co-author Massimo Della Valle (INAF- Osservatorio Astronomico di Capo- dimonte, Naples, and ICRANet, Pe- scara, Italy) explains the significance of this finding: “It is a very important step forward. If we imagine the his- tory of the chemical evolution of the Milky Way as a big jigsaw, then lithium from novae was one of the most important and puzzling missing pieces. In addition, any model of the Big Bang can be questioned until the lithium conundrum is understood.” The mass of ejected lithium in Nova Centauri 2013 is estimated to be tiny (less than a billionth of the mass of the Sun), but, as there have been many billions of novae in the history of the Milky Way, this is enough to explain the observed and unexpectedly large amounts of lithium in our galaxy. Authors Luca Pasquini (ESO, Garch- ing, Germany) and Massimo Della Valle have been looking for evi- dence of lithium in novae for more than a quarter of a century. This is the satisfying conclusion to a long search for them. And for the youn- ger lead scientist there is a diffe- rent kind of thrill: "It is very excit- ing,” says Luca Izzo, “to find some- thing that was predicted before I was born and then first observed on my birthday in 2013!” I n this image, the southern Milky Way crosses the field at La Silla Observa- tory. Within the sea of stars, a special one is shining bright (in the little yel- low circle): Nova Centauri 2013, also known as V1369 Centauri. On the left is the Swedish-ESO Submillimetre Telescope (SEST). [Y. Beletsky (LCO)/ESO] T his video sequence starts from a wide field view of the Milky Way and closes in on the bright and fa- mous pair of stars Alpha and Beta Centauri. The final image in the zoom is a closeup of the nova taken using the New Technology Telescope at ESO’s La Silla Observatory in July 2015. The nova is the brightest star close to the centre of the picture and is much fainter than it was at maximum light, when it could be seen with the naked eye. [ESO/Digi- tized Sky Survey 2/N. Risinger] n