On 14 August, Japanese amateur astronomer Koichi Igaki discovered a candidate nova in the constellation of Delphinus (dolphin) from his observing site in Yamagata. After the news hit the internet, astronomers all over the world began tracking it and, in particular, measuring its change in magnitude (apparent brightness) over time. The word 'nova' translates to 'new star'.
But don't be fooled - this star has been there all along! It's a close binary system comprising one white dwarf that was previously too faint to observe or simply not remarkable enough to plot. The white dwarf has been stealing hydrogen and helium from its companion's atmosphere, compacting it onto its own surface and heating it by millions of degrees in the process. Once the critical mass was reached, a runaway fusion process ignited brightening the star by a factor of tens of thousands. To observers on Earth, it appears as though a new star has serenely faded into view.
Nova Delphini 2013, photographed from London on 15 August. The nova is marked by red crosshairs. Delphinus is outlined in grey. (credit: Tom Kerss)
When Nova Delphini 2013 was first observed, its apparent brightness was comparable to the distant planets Uranus and Neptune. Since then, it has reached naked eye visibility from a dark site, and is readily found in binoculars or small telescopes even from heavily light-polluted locations. It seems the discovery was made quite early in the nova's life, so it's still brightening and will probably continue to after the time of writing. Delphinus is very favourably placed at this time of year, just next to the Summer Triangle. Head out between 11pm and midnight BST and use the charts below to have a go yourself. Good luck!
Looking south between 11pm to midnight, the Summer Triangle is high in the sky. Use this chart to locate Delphinus to the left (East) of Altair, the star at the bottom of the triangle. The dashed box represents the area covered by the second chart. (credit: Tom Kerss/Stellarium)
Familiarise yourself with the field of stars northwest of the dolphin asterism, and scan the sky with binoculars or a small telescope. Can you see the nova? (credit: Tom Kerss/Stellarium)
For those using setting circles or GoTo systems, the J2000 coordinates are as follows:
- R.A. = 20 23 30.68
- Dec = +20 46 03.7
