Starship Asterisk*

RCW 86: Historical Supernova Remnant

Explanation: In 185 AD, Chinese astronomers recorded the appearance of a new star in the Nanmen asterism - a part of the sky identified with Alpha and Beta Centauri on modern star charts. The new star was visible for months and is thought to be the earliest recorded supernova. This multiwavelength composite image from orbiting telescopes of the 21st century, XMM-Newton and Chandra in X-rays, and Spitzer and WISE in infrared, show supernova remnant RCW 86, understood to be the remnant of that stellar explosion. The false-color view shows interstellar gas heated by the expanding supernova shock wave at X-ray energies (blue and green) and interstellar dust radiating at cooler temperatures in infrared light (yellow and red). An abundance of the element iron and lack of a neutron star or pulsar in the remnant suggest that the original supernova was Type Ia. Type Ia supernovae are thermonuclear explosions that destroy a white dwarf star as it accretes material from a companion in a binary star system. Shock velocities measured in the X-ray emitting shell and infrared dust temperatures indicate that the remnant is expanding extremely rapidly into a remarkable low density bubble created before the explosion by the white dwarf system. Near the plane of our Milky Way Galaxy, RCW 86 is about 8,200 light-years away and has an estimated radius of 50 light-years.

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Dear APOD-makers,

I have followed and loved APOD since before even I was born. But I do not understand why the RSS feed always has yesterday's picture as "today's", necessitating a click onto the "next" page to get today's picture. Am I missing something?

Love,
A fan

ps The anagram of Hubble you provide on the anti-spam has one too many "L"s.

Speakin' of yesterday & today....
Yesterday's 'teaser' showed today's APOD's subject matter was simply, "62".
I can't find any connection, other'n RCW 86's general declination of -62°, which seems a bit of a reach (no pun intended).
What'm I missing? (& let's not try the nephelococcygiaic connection....it just ain't there!)

fakename wrote:ps The anagram of Hubble you provide on the anti-spam has one too many "L"s.

Fixed.

The Centauri group - including Alpha Centauri - is only visible from Earth's southern hemisphere. China is in the northern hemisphere.
Please explain how Chinese astronomers observed this supernova?

Maybe it was so unusual and bright and it lasted long enough for news to travel to China that they traveled to see it. Or maybe they just lived down there. Or they just recorded the news without personally witnessing it. Actually, the description just says they wrote about it. It doesn't say they observed it themselves at all.

When you zoom in on the picture, some of the stars have radially symmetric dots and/or rays around them. I assume it's a camera artifact, but why only some of the stars?

Mysturji wrote:The Centauri group - including Alpha Centauri - is only visible from Earth's southern hemisphere. China is in the northern hemisphere.
Please explain how Chinese astronomers observed this supernova?

Centaurus is not visible only from the southern hemisphere. This supernova, at a declination of -62°, was visible as far north as 30° latitude. That includes about a third of modern China, as well as Southeast Asia and the Indian subcontinent. Plenty of opportunities for Chinese observers.

Living in the South Hemisphere I'm familiar with Alpha & Beta Centauri. This supernova must have been a really amazing sight. Do you have a chart of where it was located in the sky?

geckzilla wrote:

Mysturji wrote:
The Centauri group - including Alpha Centauri - is only visible from Earth's southern hemisphere. China is in the northern hemisphere.
Please explain how Chinese astronomers observed this supernova?

Maybe it was so unusual and bright and it lasted long enough for news to travel to China that they traveled to see it. Or maybe they just lived down there. Or they just recorded the news without personally witnessing it. Actually, the description just says they wrote about it. It doesn't say they observed it themselves at all.

http://en.wikipedia.org/wiki/Centaurus#History wrote:
<<Mentioned by Eudoxus in the 4th century BCE and Aratus in the 3rd century BCE, Centaurus is an ancient constellation. Large as it is now, in earliest times it was even larger, as the constellation Lupus was a sectional asterism within Centaurus as an unspecified animal, possibly a wolf, considered to be either in the centaur's grasp or impaled on its spear. The Southern Cross, which now is pictured as overlaying the centaur's lower hind legs, was also originally a mere asterism formed of the stars composing those legs. Additionally, what is now the minor constellation Circinus was then just random stars under the centaur's front hooves. In the 2nd century AD, Claudius Ptolemy catalogued 37 stars in Centaurus.

While Centaurus now has a high southern latitude, at the dawn of civilization it was an equatorial constellation. Precession has been slowly shifting it southward for millennia, and it is now close to its maximal southern declination. Thousands of years from now it will, once again, be at lower latitudes and be visible worldwide.

In Chinese astronomy, constellation Centaurus were divided in three areas. The areas are:

• The Azure Dragon of the East (東方青龍, Dōng Fāng Qīng Lóng)
  
  The Vermillion Bird of the South (南方朱雀, Nán Fāng Zhū Què)
  
  The Southern Asterisms (近南極星區, Jìnnánjíxīngōu). Constellation Centaurus in Chinese sky is not fully seen and the unseen part were classified in The Southern Asterisms (近南極星區, Jìnnánjíxīngōu) by Xu Guangqi, based on the knowledge of western star charts. The bright stars of this constellation (α Cen, θ Cen, ε Cen and η Cen) are seen in Chinese sky, except, possibly Hadar (Beta Centauri).>>

Long Biên (Hanoi) at 21°N was one of many Chinese cities during the Han Dynasty (206 BCE – 220 CE) that could easily observe Alpha Centauri in the summertime.

http://en.wikipedia.org/wiki/Alpha_Centauri wrote:
<<Below about +29° N latitude to the equator during the northern summer, Alpha Centauri lies close to the southern horizon. The star culminates each year at midnight on 24 April or 9 p.m. on 8 June.>>

Front Office wrote:When you zoom in on the picture, some of the stars have radially symmetric dots and/or rays around them. I assume it's a camera artifact, but why only some of the stars?

There are twelve dots or rays in each case. What that suggests is that one of the cameras used has some sort of element with six-fold symmetry, such as hexagonal mirrors. Since this is a multiple wavelength image collected using three or four instruments, I assume we are only seeing the artifact around stars that are particularly bright in the wavelength range of the specific diffracting camera.

Super Nova; 2000 years ago! About the time of Christ! Posibilities? Anyway it makes a great background picture. Kind of reminds me of a dog's head!

Distance from Earth to RCW 86 Supernova 8200 light-years.
The energy of a Supernova is of magnitud very important.
Diameter this energy 50 light-years. It is a very big .

neufer wrote:While Centaurus now has a high southern latitude, at the dawn of civilization it was an equatorial constellation. Precession has been slowly shifting it southward for millennia, and it is now close to its maximal southern declination. Thousands of years from now it will, once again, be at lower latitudes and be visible worldwide.

I thought of that but admittedly didn't think it would have made a big difference in a mere 2000 years.

neufer wrote:While Centaurus now has a high southern latitude, at the dawn of civilization it was an equatorial constellation. Precession has been slowly shifting it southward for millennia, and it is now close to its maximal southern declination. Thousands of years from now it will, once again, be at lower latitudes and be visible worldwide.

This supernova was not close to being an equatorial object in 185, however. At that time, its declination was -53°, as compared to its current declination of -62°. So that raises its viewable northern latitude to about 39°, compared with the current 30°. That means it could have been seen from all of China south of Beijing.

Chris Peterson wrote:

neufer wrote:
While Centaurus now has a high southern latitude, at the dawn of civilization it was an equatorial constellation. Precession has been slowly shifting it southward for millennia, and it is now close to its maximal southern declination. Thousands of years from now it will, once again, be at lower latitudes and be visible worldwide.

This supernova was not close to being an equatorial object in 185, however. At that time, its declination was -53°, as compared to its current declination of -62°. So that raises its viewable northern latitude to about 39°, compared with the current 30°. That means it could have been seen from all of China south of Beijing.

To bad Ptolemy (c. AD 90 – c. 168) wasn't still around. (Alexandria : 31.2°N)

Centauri? Could the Chinese have SEEN this? Huh?

henrystar wrote:Centauri? Could the Chinese have SEEN this? Huh?

You should read the posts that come before yours before posting, unless you want to look a bit silly...

<Bump>:
Again, what's the ''62'' connection?

Probably a mistake. Might not be, though. You'll never know...

geckzilla wrote:

Star*Hopper wrote:
Yesterday's 'teaser' showed today's APOD's subject matter was simply, "62".

I can't find any connection, other'n RCW 86's general declination of -62°, which seems a bit of a reach (no pun intended).
What'm I missing? (& let's not try the nephelococcygiaic connection....it just ain't there!)

Probably a mistake. Might not be, though. You'll never know...

• Perhaps it was a red herring or a Freudian slip.

http://www.theatricaloutfit.org/blog/h-freud-vs-lewis wrote:
Q: What was Sigmund Freud deathly afraid of? This fear even affected where he felt comfortable staying.

A: The answer is the number 62! It’s true that Freud also had pteridophobia, a morbid fear of ferns. But the phobia that affected where he felt comfortable staying was his deathly fear of the number 62: this phobia was so intense that he would not book a room in any hotel with more than 62 rooms in case he was allotted that particular room.

http://www-rohan.sdsu.edu/~amtower/uncanny.html wrote:

THE UNCANNY
by Sigmund Freud

• "If we take another class of things, it is easy to see that there, too, it is only this factor of involuntary repetition which surrounds what would otherwise by innocent enough with an uncanny atmosphere, and forces upon us the idea of something fateful and inescapable when otherwise we should have spoken only of ‘chance’. For instance, we naturally attach no importance to the event when we hand in an overcoat and get a cloakroom ticket with the number, let us say, 62; or when we find that our cabin on a ship bears that number. But the impression is altered if two such events, each in itself indifferent, happen close together — if we come across the number 62 several times in a single day, or if we begin to notice that everything which has a number — addresses, hotel rooms, compartments in railway trains — invariably has the same one, or at all events one which contains the same figures. We do feel this to be uncanny. And unless a man is utterly hardened and proof against the lure of superstition, he will be tempted to ascribe a secret meaning to this obstinate recurrence of a number; he will take it, perhaps, as an indication of the span of life allotted to him. Or suppose one is engaged in reading the works of the famous physiologist, Hering, and within the space of a few days receives two letters from two different countries, each from a person called Hering, though one has never before had any dealings with anyone of that name. Not long ago an ingenious scientist (Kammerer, 1919) attempted to reduce coincidences of this kind to certain laws, and so deprive them of their uncanny effect. I will not venture to decide whether he has succeeded or not."

http://www.shakespeare-oxford.com/?p=39 wrote:
1926 - Sigmund Freud adopts J. Thomas Looney’s theory on the 17th Earl of Oxford. (One of Freud’s teachers, Theodor Meynert, had believed in Bacon as the true author.) Freud later confirmed this advocacy in 1935 with the revision of his Autobiographical Study.

Sigmund Freud: “I no longer believe that… the actor from Stratford was the author of the works that have been ascribed to him. Since reading Shakespeare Identified by J. Thomas Looney, I am almost convinced that the assumed name conceals the personality of Edward de Vere, Earl of Oxford… The man of Stratford seems to have nothing at all to justify his claim, whereas Oxford has almost everything.”

1930 - Canon Gerald Rendall, Gladstone professor of Greek at Liverpool’s University College, publishes Shakespeare Sonnets and Edward de Vere –another book that influenced Sigmund Freud.

neufer wrote:1930 - Canon Gerald Rendall, Gladstone professor of Greek at Liverpool’s University College, publishes Shakespeare Sonnets and Edward de Vere –another book that influenced Sigmund Freud.

No wonder Freud was so psychiatric

Star*Hopper wrote:what's the ''62'' connection?

11/11/10 (YY/MM/DD)

111110₂ = 62₁₀

Best I could do.

bystander wrote:

Star*Hopper wrote:
what's the ''62'' connection?

11/11/10 (YY/MM/DD)

111110₂ = 62₁₀

Best I could do.

Only the most geeky numerologist would have come up with THAT

http://apod.nasa.gov/htmltest/rjn_dig.html