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Tue, 21 Aug 2018
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Strange Skies


Cassiopaea

Possible nova in constellation Carina

Following the posting on the ATel #11454 about the discovery by All Sky Automated Survey for SuperNovae survey (ASAS-SN) of a new transient source, possibly a classical nova, near the Galactic plane in Carina (ASAS-SN Designation: ASASSN-18fv) I performed some follow-up of this object through a 0.43-m f/6.8 astrograph + CCD from MPC Code Q62 (iTelescope Observatory, Siding Spring).

On images taken on March 23.4, 2018 I can confirm the presence of an optical counterpart with R-filtered CCD magnitude +5.7 at coordinates:
R.A. = 10 36 15.42, Decl.= -59 35 53.7

(equinox 2000.0; UCAC-4 catalogue reference stars).

Below you can see my confirmation image (single 20-sec exposure through a 0.43-m f/6.8 astrograph + CCD), click on it for a bigger version:

Nova in Carina
© Remanzacco Blogspot

Question

Mysterious optical phenomenon sighted over Scotland

'STEVE' over Sctoland
© John Gray/Twitter @GM7PBB

Stargazers in Scotland have spotted a mysterious new celestial phenomenon -- which has been given the unlikely name 'Steve'.

Sightings of the glowing green and purple lights have been seen during displays of the Aurora Borealis overnight from the isles of Skye and Lewis.

There have also been reported sightings from near Oban in Argyll and Gairloch in Wester Ross.

Given its more accurate description of Strong Thermal Emission Velocity Enhancement, the unusual lights have already sparked the interest of scientists, photographers and astronauts, with Nasa funding a citizen science project to learn more about the optical phenomenon.

It describes Steve as a thin purple ribbon of light, aligned east to west, which can extend for hundreds or thousands of miles.

Lasting for up to an hour, it is sometimes accompanied by "a rapidly evolving green picket fence-like" aurora.


Comet 2

New Comet: C/2018 E1 (ATLAS)

CBET nr. 4494, issued on 2018, March 16, announces the discovery of an apparently asteroidal object (magnitude ~17) in the course of the "Asteroid Terrestrial-impact Last Alert System" (ATLAS) search program on CCD images obtained with a 0.5-m f/2 Schmidt reflector at Haleakala, Hawaii. Posted on the Minor Planet Center's PCCP webpage, it has been reported as showing cometary activity by CCD astrometrists elsewhere. The new comet has been designated C/2018 E1 (ATLAS).

I performed follow-up measurements of this object, while it was still on the PCCP webpage. Stacking of 5 unfiltered exposures, 60 seconds each, obtained remotely on 2018, March 12.4 from Q62 (iTelescope network) through a 0.70-m f/6.6 reflector + CCD, shows that this object is a comet with a diffuse coma about 5 arcsec in diameter. The FWHM of this object was measured about 20% wider than that of nearby field stars of similar brightness.

My confirmation image (click on it for a bigger version)
Comet C/2018 E1 Atlas
© Remanzacco Blogspot
"Pre-discovery" Panstarrs observations (2015 & 2016) were identified by R. Weryk. M.P.E.C. 2018-F10 assigns the following elliptical orbital elements to comet C/2018 E1: T 2018 Apr. 17.3; e= 0.95; Peri. = 299.47; q = 2.70; Incl.= 72.48

Sun

Impressive sun halo seen over Manila, Philippines

Sun halo over Manila
© NewsFlare
This rare sun halo amazed onlookers when it was seen in Manila, Philippines, on February 26.

The optical phenomena was caused by light reflecting through ice crystals suspended in the atmosphere.

It produced a blindingly beautiful double circular rainbow effect surrounding the mid-day sun over the city in South East Asia.


Info

Fastest burst of radio waves detected by astronomers

Radio Waves
© YouTube
We like to think we know a lot about space. We can identify the chemical composition of an exoplanet's atmosphere from light-years away, simulate conditions on an alien planet, and we almost figured out time travel using black holes. All of that only scratches the surface, though-we still don't know what dark matter is, if there's alien life out there, or even what's causing these incredibly powerful, extremely short bursts of radio waves that we've been detecting for years. The latter is especially intriguing though-especially considering astronomers have just discovered the brightest radio burst yet.

Fast radio bursts (FRBs) were only discovered in 2007, and though we've detected over 30 of them, no one knows for sure where they come from or why they're so powerful. Neutron stars, pulsars, and black holes have all been put forward as candidates, but all we know is that the source packs an incredible amount of power.

"While astronomers don't know all that much about FRBs-only tens of bursts have ever been detected-we can infer some intriguing details about them," said Danny Price, who works for the Breakthrough Listen Project.

Cloud Grey

'One of the rarest clouds ever' forms over Nevada sky

Rare horseshoe cloud
© Weather Nation
It is called a horseshoe cloud... Because, well, it's shaped like a horseshoe.

Christy Grimes caught a glimpse of what the National Weather Service calls "one of the rarest clouds ever."

Grimes shot the photos near Battle Mountain Thursday and sent them to the National Weather Service office in Elko, Nevada.

So, with it being one of the rarest clouds, everyone is stuck wondering how the clouds form.

The Elko National Weather Service office gave this great explanation:
"An updraft pushes flattish cumulus clouds up and a horizontal vortex develops from differential updraft speeds.

As the vortex climbs, it gets caught in the faster horizontal winds aloft, and the middle part of the vortex catches the faster speeds with the ends being slower.

The result is that the center of the vortex pulls out ahead. Various time lapses can be found online."
So, if you ever see a horseshoe cloud, make sure to snap a photo, because you're one of the lucky ones.

Info

Fast growing black hole defies the laws of physics

Black Hole
© YouTube
Everything that we think we knew about the growth of black holes has just been flipped on its head-scientists have discovered a massive anomaly out in space that is defying the laws of physics as we know it.

It had previously been believed that black holes at the center of galaxies grow in tandem with the star clusters around them-as a galaxy expands, the black hole will grow as well, feeding on the matter and information that it absorbs. Thus far, every supermassive black hole we've found has existed within an appropriately sized galaxy-the bigger the black hole, the bigger the galaxy around it.

As it turns out, this isn't always the case. The WISE1029+0501 is a modestly sized galaxy which, based on previous assumptions, should play host to a small-ish black hole. Not so; the supermassive black hole at its center is instead far larger than the galaxy ought to be able to support.

Rainbow

Awesome sun halos sighted in Brazil and Slovenia (PHOTO, VIDEO)

SUMMER SUN HALOS Florianópolis
© Andujar


SUMMER SUN HALOS:
Yesterday's high temperature in Florianópolis, Brazil, topped 90 degrees F, typical of the region's warm summer days. Nevertheless, when Cristiano Andujar looked up from the steps of the City Cathedral, he saw definite signs of freezing air. "There were two beautiful ice halos around the sun," he says. "People on the sidewalk were stopping and pointing."

In this photo, which Andujar took, the big ring around the sun is a common 22-degree halo, caused by sunlight shining through hexagonal ice crystals in cirrus clouds. Floating almost 10 km high, these clouds were freezing despite scorching temperatures on the streets of Florianópolis.

Info

Neutron star that defies all the rules discovered

Ultra-bright neutron star
© Chris Butler/Science Photo Library/Getty Images
An artists impression of an ultra-luminous pulsar, seen from a nearby planet.
Ultra-bright neutron stars are somehow breaking what was thought to be a hard-and-fast law of physics, by collecting matter at a rate that should be impossible.

So far, four of the unfeasibly hungry stars have been detected, with the latest described in a paper published in the journal Nature Astronomy. The small number is not necessarily an indication of rarity; the first was only discovered, by NASA's Nuclear Spectroscopic Telescope Array (NuStar), in 2014.

Or, perhaps more correctly, it was only in 2014 that a neutron star was definitively identified as the cause of a phenomenon, known as ULX, that had been initially observed in the 1980s. ULX stands for "ultra-luminous X-ray source", and characterises an astronomical X-ray source that is less bright than a galactic nucleus but brighter than pretty much everything else.

A ULX is brighter than any known star. Most galaxies seem to sport one, although some have several. The Milky Way, curiously enough, has none.

They key characteristic that makes ULXs fascinating is that they routinely exceed what is known as the Eddington limit for neutron stars and black holes.

The Eddington limit defines the point at which the outward pressure of a star's radiation matches the inward pull of its gravity. Going beyond this limit would be, in theory, immensely destructive, with the luminosity - the outwards radiation - forcefully disintegrating the star's outermost layers until the limit is once more met and equilibrium restored.

Because of this curious quality, debate has raged about what exactly the source of ULXs might be. A study in 2001 cautiously suggested that individual ULXs may contain extremely massive black holes.

Info

Powerful flare detected from Proxima Centauri

Proxima Centauri
© NRAO/AUI/NSF; D. Berry
At its peak, the newly recognized flare was 10 times brighter than our sun's largest flares, when observed at similar wavelengths. Stellar flares have not been well studied at the millimeter and submillimeter wavelengths detected by ALMA, especially around stars of Proxima Centauri's type, called M dwarfs, which are the most common in our galaxy.

"March 24, 2017, was no ordinary day for Proxima Cen," said Meredith MacGregor, an astronomer at the Carnegie Institution for Science, Department of Terrestrial Magnetism in Washington, D.C., who led the research with fellow Carnegie astronomer Alycia Weinberger. Along with colleagues from the Harvard-Smithsonian Center for Astrophysics, David Wilner and Adam Kowalski, and Steven Cranmer of the University of Colorado Boulder - they discovered the enormous flare when they reanalyzed ALMA observations taken last year.

The flare increased Proxima Centauri's brightness by 1,000 times over 10 seconds. This was preceded by a smaller flare; taken together, the whole event lasted fewer than two minutes of the 10 hours that ALMA observed the star between January and March of last year.

Stellar flares happen when a shift in the star's magnetic field accelerates electrons to speeds approaching that of light. The accelerated electrons interact with the highly charged plasma that makes up most of the star, causing an eruption that produces emission across the entire electromagnetic spectrum.

"It's likely that Proxima b was blasted by high energy radiation during this flare," MacGregor explained, adding that it was already known that Proxima Centauri experienced regular, although smaller, X-ray flares. "Over the billions of years since Proxima b formed, flares like this one could have evaporated any atmosphere or ocean and sterilized the surface, suggesting that habitability may involve more than just being the right distance from the host star to have liquid water."