A Bouquet of Novae Brightens April Nights

New bright nova
The new vivid nova, V1710 Scorpii, glows conspicuously red on this picture taken on April 14, 2021. It’s the third nova found in latest weeks that has reached ninth magnitude or brighter.
Rob Kaufman

Wait a minute. Am I going to should set the alarm and stand up at 4 a.m.? Absolutely. And I’ll do it with out criticism. Not solely are the latest novae in Cassiopeia and Sagittarius nonetheless vivid at magnitudes at 8.1 and 9.9, respectively, however a model new nova in Scorpius has simply joined the scene. Add in Comet ATLAS (C/2020 R4), now at magnitude 9.5, and you understand in your coronary heart a daybreak observing session is in your future.

Amateur astronomer Paul Camilleri of Northern Territory, Australia and the All-Sky Automated Survey for Supernovae (ASAS-SN) independently found the brand new object early on April twelfth at visible magnitude 9.5. Formally named V1710 Scorpii, it brightened shortly to eight.5 earlier than fading barely, now simmering round 9.5 as of early April fifteenth. Oscillations like these are widespread, so the nova may proceed to fade or re-brighten simply as abruptly.

In an electronic mail, Camilleri shared a cheerful coincidence: “Interestingly, this discovery is my 10th nova, and it was found 30 years to the day of my first discovery in April 1991 and a few days short of my last discovery (April 14, 1993) some 28 years ago.”

Discovery image of Nova Sco 2021
This is Paul Camilleri’s discovery picture taken on April 12.7625 UT with a Nikon D3200 DSLR and 85mm f/2 lens. The publicity was 5 seconds at ISO 6400. Since it was made on a tripod and not using a monitoring mount, the stars are barely trailed.
Paul Camillari

He famous that the nova had an orange shade on his images, probably attributable to emission from ionized hydrogen within the skinny, increasing shell of gases ejected throughout the explosion. Spectra indicate that the article is a classical nova, that means that is its first recorded eruption, and it belongs to the Fe II class, the place distinguished emission traces of ionized iron stand out in its spectrum.

It Takes Two to Tango

A nova happens when a white dwarf star siphons hydrogen gas from a intently orbiting companion star into an accretion disk, like cotton sweet wrapping round a cardboard tube. From there the fabric spirals right down to the dwarf’s floor, the place it accumulates in an ever-deepening atmospheric layer. When that layer reaches a depth of round 200 meters (650 ft), the star’s crushing gravity compacts and heats the hydrogen till it explosively fuses in a runaway thermonuclear chain response.

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

The vitality transforms the ambiance into a superb fireball that expands into space at quickens to some thousand kilometers a second. To provide you with an thought of the fireball’s measurement, when Georgia State University’s Center for High Angular Resolution Astronomy observed Nova Delphini 2013 inside 24 hours of detonation in August 2013, its diameter was roughly the scale of Earth’s orbit. Forty-three days later, the gas had ballooned to almost the scale of Neptune’s orbit.

In a nova, an in any other case obscure star system can brighten as much as 15 magnitudes in a single day, changing into seen in binoculars and even to the bare eye. The brightest of these obtain a luminosity 50,000 to 100,000 instances that of the Sun. Nova eruptions, whereas catastrophic, depart the binary intact, permitting the white dwarf to renew its wily methods as soon as the eruption subsides.

Three new novae
The three explosions holding amateurs on their toes these nights are finest seen in sequence simply earlier than daybreak. There’s additionally a 4th nova, V6594 Sagittarii (found on March 25, 2021), nevertheless it’s at present fainter at about eleventh magnitude.
Left, center: Rob Kaufman; Right: Dennis di Cicco

Later, because the fireball cools and expands and the nova fades, the increasing shell enters a nebular phase, by which it glows with the sunshine of doubly ionized oxygen (OIII), the identical gentle emitted by planetary nebulae. This stage can happen a month or extra after the preliminary blast and is value waiting for. You’ll know the shell has thinned out when the nova behaves like a small planetary and pops in brightness once you “blink” it with an OIII filter. I nonetheless discover it superb that you could see this bodily transformation with little greater than a filter and modest telescope.

Ticket to Ride

Star-hopping to Nova Sco 2021
To discover the nova, first find Mu1,21,2) Scorpii, then sweep 2.5° east to the small, vivid open cluster NGC 6281. V1710 lies simply lower than 1° northeast of the cluster. Use this AAVSO map under to pinpoint its location.
Stellarium

The area of the nova is simple to find 3.2° east-northeast of Third-magnitude Mu1,21,2) Scorpii at R.A. 17h 09m 08.1s, Decl. –37° 30′ 40.9″. It’s not quite halfway between Mu and the Stinger Stars, Shaula and Lesath, at the end of the arachnid’s tail. Don’t let the low declination put you off. From 40° north latitude V1710 Sco stands about 12° high around 4:30 a.m. local time, when it culminates in the southern sky.

Map showing location of Nova Sco 2021 on the sky
This detailed map reveals the nova’s actual location. I’ve highlighted key vivid objects shared with the Stellarium map.
Courtesy of the AAVSO with additions by the creator

With an unobstructed view within the southeast-south course it is vivid sufficient to identify in a 4-inch scope. Even within the northern U.S. the place the star squeaks by at an altitude of 5-6°, it is nonetheless reachable. Just bear in mind to carry knee-padding if you happen to’re utilizing a reflector!

You can preserve monitor of all three novae by visiting the location of the American Association of Variable Star Observers (AAVSO). Simply kind within the object’s identify within the Pick a Star field — V1710 Sco, V6595 Sgr or V1405 Cas — and click on for a listing of latest brightness estimates, a lightweight curve or to create a personalized star chart. One final bit of recommendation: Try to get to mattress early!

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