key-hole nebula

[Brian W (Brian)]

Hi, just wondering if any one can quote references as to when and who first named the key-hole nebula the key-hole nebula. Either or both of them of course.
Brian

[Rob_K]

Wikipedia says it was named by John Herschel in the 19th century. You may find out the date through links at the bottom of the page:
http://en.wikipedia.org/wiki/Carina_Nebula

Cheers -

[Rob_K]

Here's something - apparently Herschel first sketched it in 1830:

"The enigma of the dark keyhole structure dates back to 1830 and the first detailed drawings of the Keyhole nebula by Herschel, which show a keyhole shape that is somewhat different from today's picture. After much controversy about the reliability of Herschel's work, it is now generally accepted that the variations of the keyhole shape are real and were associated with the large luminosity fading of n Car after its bright phase from around 1822 to 1856"

http://iopscience.iop.org/0004-637X/...2740.text.html

Cheers -

[Rob_K]

Stop me Brian!!

Not "Keyhole", but here's the origin of "Homonculus":

'Now, more than a hundred years after Herschel, Enrique Gaviola was back, taking another careful look at Eta Carinae. For several hours he took two sets of nine images, beginning each set with a one-second exposure and doubling the exposure duration each time until the exposure for his last picture was over four minutes long.
Once developed, these images from 1945 were considered by many the best ever taken of this strange star. They showed what Gaviola humorously dubbed the Homunculus, Latin for “little man,” a kind of Pills-bury Doughboy “with its head pointing northwest, legs opposite and arms folded over a fat body.”'

http://press.princeton.edu/chapters/s8618.html

Cheers -

[Brian W (Brian)]

Stop you? never! The problem is that while many people believe H2 named it 'keyhole' no one can find the paper, correspondence, or sketch with that name by H2.
Brian

[Paddy (Patrick)]

Some great research there, Rob. And a very good question, Brian.

[Brian W (Brian)]

Rob you gave me the needed clue. Viotti in a paper he wrote states that John Herschel described the shape as LEMNISCATA which is loosely translated to 'keyhole'.
Thanks for the hint.
Brian

[SteveG (Steve)]

I am quoting here verbatim from John Herschel's Cape Observations, which has a large section devoted to the Eta Carina Nebula and of course the outburst of Eta Car that he chronicled.

"Close to the great star A, is situated that singular lemniscate-oval vacuity which forms so strange a feature of this nebula. Its area is not entirely devoid of light. A thin nebulous veil seems as if extended over its northern loop on the preceding side. Four stars, Nos. 686, 603, 589, and 670 (= [w]) of the Catalogue are placed precisely on its edges, and will serve as excellent detectors of change in its form, should any occur. The stars Nos. 607 (=[t]), 664 (=[v]), and 616, though near the edge, are yet fairly immersed in the nebula. On the other hand [u] No. 634, situated in the contraction of the oval towards its middle, though also near the edge, is yet fairly within the vacancy, and so situated that the slightest shifting of the nebulous contour at its preceding side cannot fail to rendered sensible."

Herschel's gorgeous sketch of the Eta Car nebula clearly shows a very distinctive guitar or keyhole-shaped vacuity in the nebula (much more contrasty than visible today), but I couldn't find any phrase "Keyhole" in his description. Instead he calls it a lemniscate-oval vacuity. Of course, the "Lemniscate-oval Vacuity Nebula" doesn't exactly roll off the tongue, so I'm wondering if this was just abbreviated into the Keyhole Nebula later?

[Rob_K]

Herschel studied this area and feature so much I don't think you can write it off on the basis of one tract. He wrote volumes on it over many years. The 1837 observation of the sudden brightening of Eta Argus (Carina) might hold something - a tantalising piece in a bio on the Herschel family has "Key-hole" in quotation marks in line with various other small quotes from his 1837 observation. Maybe he did coin it after all? The hunt should go on IMO!

Cheers -

[Rob_K]

I think I'm saying that the "lemniscate-oval" description might be a bit of a red herring. Lemniscate, in English at least, has no connotations of "keyhole" that I can find. It is a mathematical term describing a figure that popularly we recognise as the infinity sign. It might be possible as Brian has posted that a translation from Italian into English created the "keyhole nebula", but that seems pretty iffy. Either John Herschel wrote it or he didn't. Selective quotes from Uranometrica aren't going to solve it, only a search through his original works.

Cheers -

[Brian W (Brian)]

Rob you are right it is only by finding it in his works that this will be solved.

The question is which work.

Dating it is potentially the easiest... in his 1847 publication he discusses how the bright star in Argos went ballistic becoming the second brightest star in the heavens. This event seems to have altered the keyhole nebula so that now it really does not look like one.

So somewhere between 1830 and 47 is where it would be found.

Lemniscate is indeed the infinity sign shape but to some of us that could easily look like a keyhole for an old fashioned (make that modern for H2) key.
Brian

[SteveG (Steve)]

Out of curiosity, I took a look in Herschel's "Outlines of Astronomy" (1849), but although a page or so is devoted to Eta Car and the nebula, there's no mention of "Keyhole".

The reason I looked there is that in this book he uses the term "trifid" with regards to M20 ---

"One of the them [several nebulae in Sagittarius] is singularly trifid, consisting of three bright and irregularly formed nebulous masses, graduating away insensibly externally, but coming up to a great intensity of light at their interior edges, where they enclose and surround a sort of three-forked rift, or vacant area, abruptly and uncouthly crooked, and quite void of nebulous light. A bright triple star is situated precisely on the edge of one of these nebulous masses just where the interior vacancy forks out two channels. A fourth nebulous mass spreads like a fan or downy plume from a star at a little distance from the triple nebula."

Steve Gottlieb

[Rob_K]

Interesting Steve, thanks! And that brings up the question - is describing something as "trifid" shaped the same as naming it the Trifid Nebula? If John Herschel did describe the Argo object as "keyhole" shaped, is that the same as naming it the Keyhole Nebula? Is that two questions? Oops, three...

Steve, do you know if JH was a 'namer'? Did he routinely give celestial objects common names? (so many questions, sorry... )

Cheers

[Brian W (Brian)]

H2 observed just too many objects to give them names as a rule. Mostly he gave them numbers. Check his catalogues.

Brian

[Brian W (Brian)]

But this time according to SEDS he was the one who named M20 the Trifid. He certainly used the name in his 1847 publication.

Brian

[SteveG (Steve)]

In the Cape Catalogue, JH specifically used the term "trifid nebula" in sweep 793 (1837) so he clearly deserves credit for this nickname, but going back even earlier to his Slough Catalogue (1833) he describes "vL; trifid, three nebulae with a vacuity in the midst..."

As far as the Keyhole, I guess the jury is still out.

Here's another nickname sometimes attributed to JH -- "False Comet" for NGC 6231. Anyone know if this is true or what's the source?

[Brian W (Brian)]

Don't know if he named it but I do know he credited Australian James Dunlop with the discovery.

[Rob_K]

No primary sources, but the secondaries are pretty interesting! God I love Google!

'An email from Michael Bakich at Astronomy magazine to A. J. Crayon of the Saguaro Astronomy Club says,
"The region around and between mu Scorpii and zeta Sco, including NGC 6231, received the nickname "False Comet" from John Herschel while observing at the Cape of Good Hope from 1834 to 1838. He named it, however, not so much because it was a "fake" or "faux" or "false" comet (as, indeed, it so appears), but in honor of his landing site, False Bay. That's why we spell "False" with a capital F. Indeed, we also now call the slightly larger region around the False Comet the Table of Scorpius for the same reason. Herschel's observatory looked out toward Table Mountain, above which the Scorpion often perched. Both False Bay and Table Mountain still exist on maps of the area." '
http://www.saguaroastro.org/content/...%20Classes.pdf

A publication called "The Herschel Objects & How To Observe Them" refers to an object called "False Comet", NGC 404 in Andromeda.
http://issuu.com/peival/docs/the-her...o-observe-them

And there are some later claims!!!!

'The False Comet moniker was most likely coined by Alan Whitman's description of it at the 1983 Texas Star Party. He subsequently wrote about it in Sky Publishing's Total Solar Eclipse 1998 Sourcebook where he described it as "A striking comet-like structure streams north from the colorful naked-eye double Zeta Scorpii. The 'comet' consists of Zeta, Hartung's 'glorious cluster' C76 (NGC 6231), the elongated cluster H12, and the background glow of innumerable distant O and B stars of the I Scorpii Association, which contribute to the cometary illusion." '
http://www.perezmedia.net/beltofvenu...es/000820.html

But maybe, just maybe, we Aussies named it, LOL!

"Naked eye bright spot where Scorpius turns east; Incl CL NGC 6231; Australians call it ´The False Comet´"
http://www.nightskyatlas.com/asterisms.jsp

Cheers -

[Brian W (Brian)]

I wonder if the Aborigines had a name for it?

[SteveG (Steve)]

I checked a few more notes and articles that John wrote on Eta Car (Argo) in MNRAS but still couldn't track down any mention of a "keyhole". But he certainly liked to use the term "lemniscate"! (must have been his early mathematical training).

In 1869 there were a few correspondences published in MNRAS (titled "The Great Nebula round Eta Argus") involving John and his son, who later sketched the nebula and stars, about possible changes in the nebula. In the letters, John refers to the Keyhole several times as "the Lemniscate" (capitalization is John's) and "the Lemniscate with the Nebula".