Now is the time to catch Nova Herculis in 2021 before it disappears from view.
… And then there were two. Fresh after the Nova Cassiopeiae 2021 eruption earlier this year, another galactic nova made itself known as the “new star” or nova in the constellation Hercules the Hero on the border with Aquila the Eagle last weekend.
The discovery: The nova was discovered on the night of June 12 by the astronomer Seiji Ueda of Hokkaido, Japan, with a size of +8 ‘with a sphere’. The Nova initially received the phone number-like monikers TCP J18573095 + 1653396 (denoting their position in the sky) and ZTF (Zwicky Transient Facility) 19aasfsjq (another alphabet soup name) before being given the much simpler name Nova Herculis 2021. or simply N Her 2021. Just a few days ago, the American Association of Variable Star Observers (AAVSO) issued formal warning 745 informing observers that a new bright northern hemisphere nova was indeed afoot.
The story so far: This came up quickly when Nova Her 2021 reached magnitude +5.5 on Sunday, June 13, just one day after its discovery. At the time of writing, the Nova is a bit faded but still sits at a respectable +9 brightness that is well worth looking for with binoculars or a small telescope. Remember, if history sets a precedent, Nova Her could get brighter again in 2021 … and soon. Just look at how it flared and faded in this amazing sequence:
The pictures show the newly discovered “new” and now officially V1674 Herculis (V1674 Her). The pictures, which were taken on the 13th, 14th and 15th at 0H BRT, show the clear differences in brightness. Learn more: #ObservatorioNacional #New #Constellation # estrelas @ mcti pic.twitter.com/IsUD7tTTaD
– National Observatory (@Obs_Nacional) June 15, 2021
The position of Nova Her 2021 in the sky: First the good: The region where Nova Her 2021 is located currently ascends eastwards at sunset in mid-June for observers in the northern hemisphere. With the moon waxing towards Full on June 24th, tonight is the time to catch Nova Her 2021.
The position of the nova in the sky is:
Right ascension 18 hours 57 ’31 ”
Declination +16 degrees north, 53 ’40 ”
The general field of view for Nova Her 2021 (centered on the Telrad viewfinder). Photo credit: Stellarium / Dave Dickinson.
… and here is a narrow, two-degree viewfinder map:
N your 2021 finder. Note that FF Aquilae is the brightest star in the field, north of the center. Image credit: AAVSO.
The nova is very close (less than one degree from) the variable star FF Aquilae with a magnitude of +5.3. Notice that the famous “coat hanger” asterism is in the same general field of view:
Nova Herculis (marked) in the middle of the field of view. Photo credit: Filipp Romanov
Position of the nova in the galaxy: Like extragalactic supernovae seen in other galaxies, galactic novae tend to flare up in predictable ways, which makes them good standard candles for roughly estimating distance. Based on this, Nova Her appears to be about 18 to 20 kilos light-years (kly) away in 2021, in the galaxy’s Sagittarius arm, offset from the direction of the core of the Milky Way and about five degrees north of the galaxy plane.
Possible location (based on direction and brightness) for Nova Herculis 2021 in the Milky Way. Photo credit: NASA
What exactly is Nova Herculis 2021? Galactic novae occur when a white dwarf star accretes material from a large nearby main sequence star. This material builds up, thickens and finally gives way to a violent, out of control fusion process that ignites in brilliant flash over a period of several weeks. U Scorpii and T Pyxidis are members of a rare subcategory of variable stars known as recurring novae.
An eVscope image from New Hercules, 2021. Photo credit: Marie Billiani
How often are novae seen in our galaxy? On average, about a dozen novae are cataloged in our galaxy each year; About every ten years we get a good nova with the naked eye, which can be reached up to a brightness of +1 and which competes with all but the brightest stars and briefly changes the outlines of the host constellation. The last such example was Nova Delphini 2013 in the tiny constellation Delphinus the Dolphin.
Check out Nova Herculis 2021 while you can!