Nova in Cassiopeia (Nova Cassiopeiae 2020)


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I stumbled upon the following news in Russian.

On 26-28.07.20 two Russian astronomers discovered a Nova star in Cassiopeia constellation.

Here's an official American Association of Variable Star Observers entry (in English) with all the technical details.

Here's a detailed article about it, including pictures (in Russian).

I also found a link to an astronomical forum (in English) where Nova in Cas is being discussed.


Apparently there is some strangeness with how this nova behaves. According to this explanation (in Russian), nova stars reach a maximum magnitude within 2-3 days, but in case of this nova, its magnitude was rising for two weeks, and then it was fading, and then rising again. Here's a diagram. Astronomers are saying that it is quite unusual, and the reason for it is still a mystery. All the observatories, or anyone with appropriate telescopes are asked to observe the star.

N Cas 2020.gif


P.S. Apparently Cassiopeia novae tend to be "unusual". There is this nova that was filmed on 15th of December, 1993, and there is also this one filmed on 24th of August, 1995. That's what was said about the 1995 nova in Cas:

The early lightcurve is very unusual. The rise to maximum was very slow and the nova peaked at mag 7.1 near JD 2450070. 65 days later, near JD 2450135 a second maximum occurred at approximately mag 8.0. This was followed, about 55 days later on JD 2450190 with a third maximum at about magnitude 8.6. Thereafter the nova faded to about mag 10 after which small fluctuations have been present. Certainly a very unusual nova which deserves close attention!
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Great find Keit thank you.

Interesting to note that the Nova in Cassiopeia back in 1572 was seen by many as a herald of great change - and of course the mini-ice age kicked in soon after.

SN 1572 (Tycho's Supernova, Tycho's Nova), or B Cassiopeiae (B Cas), was a supernova of Type Ia in the constellation Cassiopeia, one of eight supernovae visible to the naked eye in historical records. It appeared in early November 1572 and was independently discovered by many individuals.
Interesting to note that the Nova in Cassiopeia back in 1572 was seen by many as a herald of great change - and of course the mini-ice age kicked in soon after.

Just a note that there is a difference between nova and supernova. And novae happen much more frequently. There are more than 400 recorded so far.

From here:

A nova is an explosion from the surface of a white-dwarf star in a binary star system. A nova occurs when the white dwarf, which is the dense core of a once-normal star, “steals” gas from its nearby companion star. When enough gas builts up on the surface of the white dwarf it triggers an explosion. For a brief time, the system can shine up to a million times brighter than normal. As long as it continues to take gas from its companion star, the white dwarf can produce nova outbursts at regular intervals. A supernova is a violent stellar explosion that can shine as brightly as an entire galaxy of billions of normal stars.
Just a note that there is a difference between nova and supernova. And novae happen much more frequently. There are more than 400 recorded so far.

Absolutely Keit. Its just that back in the 16th century astronomers blurred the lines between the two phenomena and tended to refer to them all as Nova - hence Tycvho's Supernova in B Cassiopeiae was known generally as Tycho's Nova.
A bright nova was found in the constellation Perseus. It was Seiji Ueda of Kushiro City, Hokkaido, who discovered the nova. Mr. Ueda took a picture of Perseus on November 25.807 (Universal Time, the same below.

In Japan, around 4:22 on the 26th) using a lens with a focal length of 200 mm and a digital camera. I found. A group of S. Korotkiy and others at the Ka-Dar Observatory in Russia also independently discovered this object on 25.844 days.

According to the observation by Mr. Shizuo Kaneko of Shizuoka Prefecture, it was found that this object was still darker than 14.9 mag 4.6 hours before Mr. Ueda's discovery, and suddenly brightened in a very short time.

Following the report of the discovery, many observers such as Seiichiro Kiyota, Katsumi Yoshimoto, Yasuo Sano, Toshihide Noguchi, and Nayoro Observatory conducted confirmation observations of this object.

According to detailed observations after the discovery, the exact location of this object is as follows. Spectroscopic observations of the celestial body were carried out by a group of U. Munari et al.

On November 26.05, and it was found that the spectrum shows the emission lines of the Balmer series of hydrogen with the P Cyg profile. From these spectral features, it was found that this object is a classical nova near the maximum.

The nova continued to brighten after its discovery and brightened to 8.5 mag around November 28. As of November 29, it is still in the high 8s and not so dark, and it seems that it can be seen visually with an astronomical telescope with an aperture of about 8 cm for the past few days. Attention will be paid to changes in brightness in the future.

Mr. Ueda has discovered more than 700 asteroids through joint observations with Mr. Hiroshi Kaneda, but this is the first time he has discovered a nova.

on 28 Nov 2020; 05:28 UT
Subjects: Optical, Nova
"Reverse hybrid" behavior of Nova Per 2020 = TCP J04291888+4354233
Sandipan Borthakur, Vipin Kumar, Vishal Joshi, Mudit Srivastava, Dipankar P K Banerjee (Physical Research Laboratory, Ahmedabad, India)

We confirm the findings of Munari et al. (ATel #14229) about a rapid evolution in the spectra of Nova Per 2020 as it rises towards maximum. TCP J04291888+4354233 was discovered by Seiji Ueda on UT 2020 Nov 25.813. We obtained optical spectra of the nova on subsequent nights on UT 2020 Nov 26.88 and on UT 2020 Nov 27.68 using the Mt. Abu Faint Object Spectrograph and Camera - Pathfinder (MFOSC-P) instrument on the PRL 1.2m Telescope at Mt. Abu, India. The spectra were recorded in two modes: Low-resolution mode with R ~ 500-600 covering the 4400-9000A region and a R ~ 2000 mode covering 6100-7100A centered around H-alpha.

Consistent with Munari et al. (ATel #14229), we also find that that the first night's spectrum showed prominent presence of several HeI lines (5876, 6678, 7065 Ang) accompanied by strong P Cygni features, NII (multiplet 3), and CII 7235A. However, on the second night, these lines have disappeared or weakened very largely and are replaced by FeII lines (prominent being the lines of the 42, 48, and 49 multiplets) with pronounced P-Cyg absorption features. The appearance in the latter spectrum is that of a conventional Fe II class of nova. The H-alpha profile, taken with R = 2000, shows a rather dramatic change with clearly separated red and blue peaks on the first night with the blue peak significantly stronger and peak separation of 850 km/s. On the second night the double-peaked structure is not seen anymore (in the spectrum at R = 2000). On both nights, H-alpha displays a prominent P Cygni profile and the emission component has FWHM of ~ 1500 to 1600 km/s on both nights.

Thus the object shows a transition from a nova with some He/N spectral characteristics to a nova of the Fe II class, which is in the opposite sense of the transition observed in hybrid or FeIIb novae proposed by Williams (1992, AJ, 104, 725) in his classification scheme. Hence we refer to this as a reverse hybrid behavior. Hybrid or FeIIb novae sequentially exhibit both classes of spectra making a fairly rapid transition in a matter of weeks from an initial FeII spectrum to a He/N spectrum before developing into the nebular stage (Williams 1992). The reverse hybrid behavior seen here is rather uncommon. In recent times it has been seen, for example, in the optical and NIR spectra of the recurrent nova T Pyx (A. Ederoclite, 2014, ASPC, 490, 163; Joshi, Banerjee et al. 2014, MNRAS, 443, 559) and in V5558 Sgr in the optical (Tanaka J., et al. 2011, PASJ, 63, 911). We strongly encourage further monitoring of this nova.

New nova in Cassiopeia! And it's visible using binoculars.

An amateur astronomer just spotted a strange new object in the sky. And it’s bright enough for you to see with binoculars from your backyard.


At around 7 P.M. JST on the evening of March 18, Japanese amateur astronomer Yuji Nakamura spotted something strange: A new point of light in the familiar constellation Cassiopeia the Queen.

Researchers at Kyoto University quickly followed up using the 3.8-meter Seimei Telescope atop Mt. Chikurinji in Japan. They obtained a spectrum of the new object, hoping to determine its nature based on clues hiding in its light.

They discovered that the object, which is cataloged as PNV J23244760+6111140, is a classical nova: An outburst from a white dwarf that’s stealing matter from its nearby companion star.

The new nova is growing brighter, too. At the time of its discovery (March 18), it was shining at magnitude 9.6. But within a matter of hours, it had brightened to magnitude 9.1. Images taken earlier today (March 19), show it has brightened yet again, reaching magnitude 7.8. That’s bright enough to spot it with binoculars from your backyard.
New nova in Cassiopeia! And it's visible using binoculars.

I've just noticed this article from Sky and Telescope about the new Nova -

I know others saw this but wanted to nova visible from Cassiopeia!
The C's have been telling us important information for years... Now the constellation has a new nova... Timing?

I saw this posted on the Sky FB page today:

I wasn't sure where the new Nova was on that image so i did a quick search and the main website has another image that apparently shows the location and a zoomed in image of the new Nova, named Nova 2021 Cas:

In dark sky areas, the naked eye is able to see more than 3.000 stars. Our Galaxy contains more than 100.000.000 stars. Now just imagine that feeling to discover a new tiny shining dot. Exactly this happened just a few weeks ago when Japanese observer Yuji Nakamura looked at the camera and find “new star”. In fact, it was a Nova – later named Nova 2021 Cas in the Cassiopeia constellation. And I sought to photograph this little object above the High Tatras mountains in Slovakia. You can notice the very bright stars from the Cassiopeia constellation looking like a “W”, emission nebulas, Milky Way, and Nova 2021 Cas itself.

Equipment: Canon 6D mod, Sigma Art 50mm, Sky-Watcher Star Adventurer, Optolong L-Pro, Astronomik Ha 12nm
Category: Tracked Ha+RGB pano
Date: 17th of May, 2021
Location: Strbske Pleso, High Tatras

Apparently nova in Cassiopeia is behaving quite irregularly, and is again visible to the naked eye.

That's what it says on one of the Russian astronomy sites:

A new star discovered on March 18, 2021 by amateur astronomer Yuji Nakamura of Japan is quite unusual. Classic new stars usually reach their maximum brightness 2-3 days after the outburst, but Nova Cassiopeia 2021 first showed a rise in brightness, then a long decline in brightness for nearly a month, then a rise again and a second short peak at +5.2 magnitude. After this peak, its brightness varied in the range of +6.5-8.4 magnitude.

Since July 11, the brightness of Nova has been increasing steadily, reaching +5.8 magnitude, according to visual and photometric estimates, published on the website of the American Association of Variable Star Observers. Thus, it is again available to observe with the naked eye in the dark sky!

The reason for the behavior of this object remains a mystery. Nova Cassiopeia 2021 is the brightest New Star in the northern sky in nearly 8 years
(Nova Delphini reached magnitude of+4.3 in 2013).


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