On August 10, 2021, Philip Romanov took a photo of RS Ophiuchus in Yuzhnow-Morskoy, Russia, a new star visible to the naked eye. He wrote in the report: "The re-emergence of the nova RS Ophiuchus has broken out. I saw the star with the naked eye, which was about 4.6 magnitude bright. On August 9, 2021, between 3:19 p.m. and 22 p.m., I took these photos in my home town. I waited for hours before the shoot and the sky was clear for a few minutes. ”
A rare new star visible to the naked eye
On August 21, 2021, RS Ophiuchus, which astronomers call a nova, entered the range of Earth's observations, a new star that can be observed directly with the naked eye. It's nowhere near as bright as the brightest planets, but in the pitch-black night sky you'll be able to reach the range of Ophiuchus. See it shine inside. Earlier this week, the nova was said to have a magnitude of 4.3. If the rumors were true, the star would be much brighter than expected. The magnitude of RS Ophiuchus is generally maintained at around 12, and when viewed with the naked eye or most backyard telescopes, it usually fails because it is too dim. But a sudden burst of thermonuclear bursts in the star's surface can make it hundreds of times brighter.
Nor is it the first time that RS Ophiuchus has become a nova, as it is in a periodic nova system, i.e., a system that itself produces regular explosions. RS Ophiuchus is part of a binary system, one is a white dwarf, which is very compact and has completed high evolution; the other is a red giant. White dwarfs can cause explosions when they accelerate or absorb too much of the red giant's material. This is because too much material accumulates in the hydrogen layer on the surface of the white dwarf star and triggers a thermonuclear explosion. You'll notice that this is a cyclical phenomenon because the two stars are pulling at each other while they are orbiting each other. The most recent nova change in this binary system was in 2006, but the famous explosion dates back to 1898.
On Aug. 9, 2021, Greg Redfem in central Virginia snapped this photo of the Ophiuchus RS. "The color of the nova Ophiuchus RS, I think, should be the orange of the thermonuclear explosion." This photo can be viewed at Earthsky Community Photos.
How to find RS Ophiuchus
New stars have illuminated the sky this week, but may now be starting to darken. Before August 10, the nova was no longer brighter than 5 magnitudes (brightness data from the American Association of Variable StarObservers). Although this is within the maximum observed brightness of the naked eye, it is also difficult to see. If you can see it, take the time to watch it.
The Ophiuchus constellation is now located south after sunset, above the more well-known Sagittarius Teapot Constellation, which is closer to the horizon than the Ophiuchus constellation. If you look up from the "spout" of the Teapot Constellation and look through the cloud-filled spiral arm of the Milky Way, you can see the sky where RS Ophiuchus is located.
On Aug. 11, 2021, Ken Chan of Padora Valley, California, took this photo. He introduced, "RS Ophiuchus is a binary star system consisting of a red giant star and a white dwarf star. Recently, due to the explosion of objects attracted from the red giant star, which brought about a thermonuclear reaction, there was a temporary change in brightness on the white dwarf. The new star reappears about 15 years ago. "Thank you, Ken!
The brightest star in the constellation Ophiuchus is Rasalhague, located near the top of the constellation, and the second brightest star is Sabik, located near the base of the constellation. RS Ophiuchus is located slightly to the right between the two stars. You can use the photo above as a catalogue to find the correct position, and then use the photo below to narrow the field of view.
On August 9, 2021, Peter Forest photographed this Ophiuchus RS in Charlottesville, Virginia. He wrote: "I captured this extremely rare astronomical phenomenon – a recurring explosion of new stars. The nova in the constellation Ophiuchus can be observed with the naked eye, but when its brightness rapidly diminishes over the next few days, the phenomenon is no longer visible to the naked eye. It was an unexpected thermonuclear explosion in RS Ophiuchus — a phenomenon that last occurred in 2006. The night after the nova explosion was clear, which is why I was so lucky to observe this phenomenon. "Thank you, Peter!
Observer reports on RS Ophiuchus
Observers socially shared their stories about RS Ophiuchus
Just went out and caught the Ophiuchus RS with my phone (also saw the very beautiful Perseus)
——TimO'Brien, @ProfTimOB, August 9, 2021
Two days ago, the repeated eruptions of the RS Nova Ophiuchus made it grandly displayed on our ASAS-SN pictures!
Yesterday, the variable star Ophiuchus RS broke out in Ophiuchus. Although it is 5,000 light-years away, the burst is bright enough for us to observe with the naked eye after sunset.
The Ophiuchus RS is now erupting on level 4.5!! Go and observe!
—Dr. Stella Kafka, @stellakafka, August 9, 2021
Written at the end, RS Ophiuchus is a star system that is experiencing repeated bursts of novae, and in August 2021, a new star appeared in the naked eye of observers. Can it still be seen? The only way to know the answer is to observe.
BY：KellyKizer Whitt
FY：Astronomicalvolunteer team
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