Recurrent Nova RS Ophiuchi Just Blew its Top!

RS Oph animation
The recurrent nova RS Ophiuchi dramatically brightened from magnitude 11.2 to 4.8 over August 8-9, 2021. The outburst picture was taken on August 9.42 UT and paired with an older photograph from the Palomar Observatory Sky Survey (POSS) from July 1989 when the star was at minimal. Ernesto Guido, Marco Rocchetto & Adriano Valvasori / telescope.live

A star that usually slumbers round twelfth magnitude all of a sudden “woke up” seven magnitudes brighter this previous weekend. Now you possibly can see it with the bare eye!

Irish beginner Keith Geary was the primary to report the shock outburst of RS Ophiuchi, one of many few identified recurrent novae. He captured photographs of it obtrusive at magnitude 5.0 together with his DSLR digital camera at 22:20 UT on August eighth and confirmed his statement in binoculars. Fellow AAVSO member Alexandre Amorim of Brazil additionally noticed the eruption 25 minutes earlier.

RS Ophiuchi wide-view map
RS Ophiuchi is positioned in jap Ophiuchus close to the Serpens border and well-placed for observing at dusk.
Stellarium

Since then, the star has brightened as much as magnitude 4.5 (August 9.7 UT), making it a comparatively simple naked-eye object even from outer suburban areas and a cinch to see in binoculars.

RS Ophiuchi light curve
The mild curve of RS Ophiuchi throughout its final outburst in 2006 reveals the fast rise, comparatively quick decline and a slower drop-off again to minimal mild over a interval of about six weeks.
Courtesy of the AAVSO

Typically, RS Oph rises steeply and quickly to most after which shortly declines, dropping about two magnitudes over a week’s time, earlier than leveling off and fading extra progressively. The outburst will make for thrilling observing in binoculars and small telescopes within the coming days. Try to catch the star at each alternative you possibly can as a result of the following blast will not seemingly recur for an additional 15 or 20 years!

Use this zoomed-in map to pinpoint the recurrent nova. Both Mu (μ) and Nu (ν) Ophiuchi make useful information stars. Numbers are magnitudes with the decimals omitted and correspond with the stars on the extra detailed AAVSO map under.
Stellarium

RS Ophiuchi final blew its prime in February 2006 and earlier than that in January 1985. The course of that makes a recurrent nova is actually the identical as within the classical selection: A white dwarf and a donor star orbit in a detailed binary system. As the donor star evolves — a red large within the case of RS Ophiuchi — it overflows its Roche Lobe and the white dwarf snatches the spilling gas (largely hydrogen), which types a spinning accretion disk across the compact star.

Nova illustration
In this artist view, a white dwarf (left) robs gas from its companion star. The materials types an accretion disk across the dwarf earlier than spiraling all the way down to the floor the place it is compressed and ignites in a thermonuclear blast.
ESO / M. Kornmesser

Material within the disk funnels to the dwarf’s floor, the place it is compacted and heated till the bottom layer reaches about 10 million levels Celsius. It then ignites in a thermonuclear explosion which blows the envelope of fabric into space at excessive speed and makes one heck of a shiny blast. According to latest observations reported within the Astronomer’s Telegram, RS Ophiuchi is expelling materials at round 2,600 kilometers per second.

Recurrent novae repeat the nova course of roughly each 10 to 100 years, whereas nova outbursts are thought to repeat on for much longer timescales from round 1,000 to 100,000 years. You cannot wait round for a nova to go nova once more, however for the roughly 10 recurrent novae (sure, they’re uncommon!), when you dwell properly you possibly can see a repeat or two in a lifetime.

RS Ophiuchi AAVSO chart
This chart from the American Association of Variable Star Observers (AAVSO) contains magnitudes (with decimals omitted) so you possibly can examine RS Oph in opposition to stars of identified brightness to observe its mild range.
Courtesy of the AAVSO

I like it when amateurs uncover issues. I requested Geary if he would share his discovery account, which you will discover under. I feel you will wholeheartedly agree together with his conclusion.

“I have been following this star and many other variables since the year 2003. I regularly submit my observations to the AAVSO,” mentioned Geary.

Keith Geary portrait
Irish beginner astronomer Keith Geary was the primary to report the present RS Ophiuchi outburst.
Courtesy of Keith Geary

“I had been on a family holiday visiting my parents in Waterford, Ireland. Up to last night I had eight nights of cloudy weather, however I persevered and made my way to a familiar observing spot called Dunbratton County awaiting nightfall.  I began my visual and DSLR nova patrol using my APM 20×100 binoculars and Canon 6D at 21:30 UT, until I took a regular shot of the RS Ophiuchi region at 22:20 UT with my Canon 200-mm f/2.8 lens.

I examined the image and immediately thought that I had made an error. I thought I was off target. To my amazement after re-examining my image I could see RS Ophiuchi shining at magnitude 5.0. I was astounded as it was my first ever success!  I immediately emailed CBAT and the AAVSO to raise the alert.

Persistence pays off! I would encourage anyone reading this article to take up variable star astronomy, who knows what the heavens will show us all next!”

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