Rare 'recurrent nova' visible to unaided eye in the constellation Ophiuchus

Rare 'recurrent nova' visible to unaided eye in the constellation Ophiuchus

A rare 'recurrent nova' event is visible to the unaided eye in the constellation of Ophiuchus this week. 

  • RS Ophiuchi (RS Oph) is a recurrent nova system, located about 5 000 light-years away from Earth, with a recurrence rate of about 15 - 20 years.
  • Its last outburst took place in 2006.

The 2021 outburst was spotted by Keith Geary from Ireland at 21:55 UTC on August 8, when the brightening increased from magnitude +12 to +5 -- about 600-fold.

On August 10, variable star observer Filipp Romanov of Yuzhno-Morskoy, Russia, reported the magnitude has increased further to +4.6.

This system has an apparent magnitude of about 12.5 in quiet phases but during outbursts, such as observed in 1898, 1933, 1958, 1967, 1985, 2006, and 2021, it can average about magnitude 5.

The recurring nova is produced by a white dwarf star and a red giant in a binary system.

Only 7 star systems in the whole Milky Way galaxy are known to produce such explosions, said Dr. Tony Phillips of SpaceWeather.com.

"At 5th magnitude, the current outburst is visible to the unaided eye, albeit just barely," Phillips said.

"Binoculars or a telescope will allow you to see it with ease. Look south after sunset. Ophiuchus hangs high in the sky just above the better-known constellations Scorpius and Sagittarius."

The last large outburst of RS Oph took place in February 2006 when it reached a visual magnitude of 4.5:

Recurrent nova in RS Ophiuchi on February 23, 2006 as seen from Mt. Laguna, California, US. Credit: Robogun

If you are new to night sky watching, you can use a mobile app to locate Ophiuchus within a minute.

Featured image credit: RS Ophiuchi outburst taken by Ernesto Guido, Marco Rocchetto & Adriano Valvasori on August 9, 2021 @ Remotely from Australia through TELESCOPE LIVE network https://telescope.live/ (via SpaceWeatherGallery)


Bill H 1 month ago

What are these things called "Stars"? I live in a state that has 24/7 clouds. A comet comes, clouds. Solar Eclipse? Clouds. "Blue Moon"? Clouds.

Jamal Shrair 1 month ago

The myths of supernovae.......................................According to current science, there are two types of supernovae, classical novae and recurrent novae. The 8 recurrent novae astronomers know about tend to be slightly brighter than classical novae in their quiescent state. Classical novae have only been seen in outburst once recurrent novae have undergone at least two outbursts over the past century (since astronomers started taking notice!). The time interval between outbursts varies from 10 to 100 years. Thus, the processes that cause the classical novae and the recurrent novae have to be different, but it is believed that the two types arise in the same way. And, it is obvious that what considered, to be classical novae is also recurrent novae given enough time (more than 100years). Theoreticians also, invented the so-called runaway thermonuclear reaction that takes place on the SURFACE! and at about 10 million Kelvin. The myth of the supernova-remnant is also believed to be the cause of cosmic-ray acceleration (The origin of Galactic cosmic-ray ions). Nonetheless, the current theories of supernovae cannot even be considered as pseudoscience, but rather pure myths.

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