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David Knisely
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Re: The Red Sirius new [Re: Crossen]
      #3405608 - 10/23/09 05:19 AM

Yes, this is all very nice, but the question is; are we interpreting what they wrote properly and accurately? Do we really know exactly what they meant? There appears to be some question here as to whether they really meant that Sirius was red all the time no matter where it was in the sky or just behaved in a "fiery" manner due to scintillation. From an astrophysical point of view, there is no evidence that Sirius-B was a red giant in historic times. There is also some contradictory evidence from other writers or observers that Sirius was reported as white rather than red:

http://shc2000.sjtu.edu.cn/031207/sirius.htm

So we are left in something of a quandary. At this point, I think that there just isn't quite enough evidence to point to Sirius being much different than it is now. Clear skies to you.


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deSitter
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Re: The Red Sirius new [Re: David Knisely]
      #3405658 - 10/23/09 06:43 AM

Again I would point out the simple calculation of the apparent brightness of say Betelgeuse or Antares at the distance of Sirius, roughly 100 times closer than either. The laws of light propagation show that the surface brightness does not change with distance - now something that is 100 times closer will have 100^2 or 10,000 times the area as something of the same physical size at the original distance - assuming that each part of the star shines with the same brightness (more or less, discounting fall-off at the limb) then moving a star 100 times closer means making it 10,000 times brighter - now 5 magnitudes is a factor of 100, so we're talking about a magnitude difference of 10 - Betelgeuse at the distance of Sirius would be magnitude -10 roughly, more than 100 times brighter than Venus - it would cast shadows at night and be visible in daylight without any effort. So there is not really any possibility that Sirius-B or any other nearby star was a red giant in historical time.

-drl


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hfjacinto
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Re: The Red Sirius new [Re: deSitter]
      #3406145 - 10/23/09 12:22 PM

I have to say I like reading smart pondering on what the ancients wrote.

I for one can agree with most of what was written. But I have a question can Sirius B have been in front of Sirius A in line of sight to Earth?

Could red Sirius been an usually bright Sirius B being illuminated by Sirius A?

The magnitude would have been minimal in increase.


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David Knisely
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Re: The Red Sirius new [Re: deSitter]
      #3406326 - 10/23/09 01:56 PM

Quote:

Again I would point out the simple calculation of the apparent brightness of say Betelgeuse or Antares at the distance of Sirius, roughly 100 times closer than either. The laws of light propagation show that the surface brightness does not change with distance - now something that is 100 times closer will have 100^2 or 10,000 times the area as something of the same physical size at the original distance - assuming that each part of the star shines with the same brightness (more or less, discounting fall-off at the limb) then moving a star 100 times closer means making it 10,000 times brighter - now 5 magnitudes is a factor of 100, so we're talking about a magnitude difference of 10 - Betelgeuse at the distance of Sirius would be magnitude -10 roughly, more than 100 times brighter than Venus - it would cast shadows at night and be visible in daylight without any effort. So there is not really any possibility that Sirius-B or any other nearby star was a red giant in historical time.

-drl




The current mass of the Sirius-B white dwarf is on the order of one solar mass. This points to an original mass of around five solar masses for the star prior to its white dwarf stage, so any red giant phase star would not have had nearly the intrinsic brightness of red giants like Betelgeuse (at least 18 solar masses) or Antares (15 to 18 solar masses). The absolute magnitude of a five solar mass red giant would probably be in the -3 to -4 range depending on exactly where the star was in its red giant stage. At the distance of Sirius, that would make the giant a visual magnitude of between roughly -7.6 and -8.6 even without including the contribution of Sirius A itself. It would shine far brighter than Venus does and might be roughly comparable to the brightness of a first-quarter moon. Clear skies to you.


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Uncle Burnout
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Re: The Red Sirius new [Re: mloffland]
      #3406431 - 10/23/09 02:40 PM

Taking a look at (my complete though very ancient) Lidell and Scott, "hypokirros" (assuming this is the word you transliterate as hypocirros) has only "somewhat yellow" as the definition and a scant 2 references, neither to Ptolemy. "Kirros" (of which the word in question is a compount) is defined as "tawny, orange-tawny, between purros and xsanthos". There is definitely a yellow component implied, in my opinion. Perhaps there are newer and better definitions available?

Rutilus, according to the OLD (Oxford Latin Dictionary) is often taken to mean glowing red, but also can be taken as "golden" or "orange" and definitely has associations with fire and the rising sun, but also to the hair color of ancient Germans (yellow or reddish blond, pehaps?), the color of metallic gold, etc. It may be in the secondary sense that rutilus is considered a proper translation, i.e., warm and brilliant.

As far as I'm concerned, the fact that Cicero and the others translated a word probably meaning "somewhat yellow" with a word maybe meaning "red" or "golden" or even "tawny" probably means nothing, except that they understood more about the ancient conceptions of color than we do. Try reading Isidore's classification on the different colors of horses, for a nice demonstration on just how seriously the ancients took these things at times.

Unfortunately, all of the Roman authors you cite are in fact little more than translators (or perhaps re-organizers) when it comes to scholarly works on natural science, though their importance to history is great, as you say. Which is to say that they probably translated to the best of their considerable abilities, but most likely never bothered to verify the material. In this case, the "redness" of rutilus (the translation) is far more convincing than the original term, but far from unambiguous.

Anyway, I don't agree that Sirius must necessarily have been percieved by the Greek and Latin sources cited as "red", but I did enjoy your article immensely and want to stress that this is just my understanding and an attempt to further the conversation.


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sp.
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Re: The Red Sirius new [Re: Uncle Burnout]
      #3406535 - 10/23/09 03:41 PM

Very interesting. Maybe the lifecycle is totally different of a star which has a close neighbourhood, the A . Maybe, thats why B can not became a real red giant or nova. Maybe, that neighbour steal/blow the mass. I think the story must be different, if a star is alone or they are together.
sp.
(but maybe im stupid)


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jrbarnett
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Re: The Red Sirius new [Re: David Knisely]
      #3406794 - 10/23/09 05:52 PM

I suppose that certain of the references *could* be subject to interpretations where the adjective being used to infre "redness" has alternative meanings that might imply "fiery" or "golden", but there seems to be a fairly large volume of material from widely different sources spanning a couple of thousand years where writers use a variety of different adjectives that imply redness. Even after you factor in that certain of the writers were not astronomers, and may have been basing their color attribution on earlier writings, I find it more probable that those authors with first-hand observing experience said "red" because that is what they saw.

I also find the "misidentification" argument (i.e., the writers said "Sirius" but actually meant another, truly red, bright star") to be far fetched. If you buy that, perhaps also we should concerned that ancient literary references to "cows" actually refer to "sparrows". In fact, in a world devoid of television, radio, rapid modes of transportation, etc., folks had much more time to be outside and to look up. I would wager that the average Joe on the street in ancient times was far more knowledgeable about star names, locations and the like than the average mass-media-innundated modern person.

Regards,

Jim


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Uncle Burnout
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Re: The Red Sirius new [Re: jrbarnett]
      #3407112 - 10/23/09 09:26 PM

Here's a passage from Manilius' Astronomicon bk. I (1st century AD), clearly describing the star as "blue". Surely there are others.

subsequitur rapido contenta Canicula cursu,
qua nullum terris violentius advenit astrum
nec gravius cedit; nunc horrida frigore surgit,
nunc vacuum soli fulgentem deserit orbem:
sic in utrumque movet mundum et contraria reddit.
hanc qui surgentem, primo cum redditur ortu,
montis ab excelso speculantur vertice Tauri,
eventus frugum varios et tempora dicunt,
quaeque valetudo veniat, concordia quanta;
bella facit pacemque refert varieque revertens
sic movet, ut vidit mundum, vultuque gubernat.
magna fides hoc posse color cursusque micantis
in radios: vix sole minor, nisi quod procul haerens
frigida caeruleo contorquet lumina vultu.
cetera vincuntur specie, nec clarius astrum
tinguitur oceano caelumve revisit ab undis.


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David Knisely
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Re: The Red Sirius new [Re: sp.]
      #3407531 - 10/24/09 01:25 AM

Quote:

Very interesting. Maybe the lifecycle is totally different of a star which has a close neighbourhood, the A . Maybe, thats why B can not became a real red giant or nova. Maybe, that neighbour steal/blow the mass. I think the story must be different, if a star is alone or they are together.
sp.
(but maybe im stupid)




No, the two stars never approach each other closely enough to exchange a significant amount of mass, so a nova is not possible with the Sirius system (periastron of about 8.1 A.U.). The B component very probably *was* once a red giant in the distant past, but that was probably several million years ago at the latest (and probably a lot earlier than that). It is now a one solar mass white dwarf. Clear skies to you.


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Dave Mitsky
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Re: The Red Sirius new [Re: David Knisely]
      #3407627 - 10/24/09 03:50 AM

As far as the possibility of Sirius being red in the not-too-distant past, I'll put my money on astrophysics.

Dave Mitsky


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jrbarnett
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Re: The Red Sirius new [Re: Uncle Burnout]
      #3408037 - 10/24/09 11:33 AM

Marcus Manilius is an interesting figure, not so much for his surviving astrological poem, but for the fact that no one seems to know anything at all about him. There's no certainty even as to his name. In the early books of Astronomica he remains nameless, adopting the name "Manilius" on in later books. No other ancient author quotes from or even mentions Manilius. He uses distinctive (and odd) grammatical construction.

None of this discounts what you've quoted, of course. He clearly does use adjectives and other descriptors that mean "blue" (if I read the passage correctly - not a given since I haven't translated any Latin in 25 years ). Unfortunately Manilius is obscure enough that I could not find any free, online English translations of the work. The references I see are "caeruleo" and "clarius astrum
tinguitur oceano". Cerulean blue and tinted like the sea.

I would be interested to know whether Manilius describes any other bright stars of known color elsewhere in the work, and if so whether he correctly attributes color to those stars?

I'm interested enough to order a copy of the Loeb translation in fact (I figure that the Creech translation would be in Elizabethan English anyway, and almost as hard (for me) to read as the Latin text.)

One other interesting point - Manilius calls the Dog Star blue. Meticulous Chinese astronomers, on the other hand, called it white. Granted that both blue and white are closer to what we see today, but it is interesting that the Chinese sources do not attribute any blueness.

Lastly, I agree that it would be great to find other early sources that refer to Sirius as something other than ruddy. Given that is one of the "Behenian fixed stars" used in astrology, I would expect there to be other ancient and medieval references to Sirius and its color.

Nice find, by the way.

- Jim


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Uncle Burnout
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Re: The Red Sirius new [Re: jrbarnett]
      #3408366 - 10/24/09 03:02 PM

I think your Latin is good and doubt you even need the Loeb for Manilius (if that's his real name)! I will see what I can dig up with other stars, as you raise a good point. Being somewhat indifferent to color myself, blue seems reasonable, but I wonder if the description "lumina frigida" doesn't imply a cool, "whitish" cast.

I also ran across references to a 4th century (?) passage by Avenius, who is even less known to me, but haven't had a chance to look it up.

I'm still frankly stumped by the Seneca passage: "Rubor" is about as red as it gets, but there seems to be a possibility that the passage is implying a color imparted by atmospheric conditions more than an inherent color of the star. I'm also uncertain about Gregory's "rubeola", since it would be typical of someone at that time period to simply pass along what he thought understood from an earlier text, but that is not a satisfying explanation to me, either.

Otherwise, I'm almost certain the term Ptolemy used is (incorrectly) translated by "fiery red" simply because most of the other stars he names fit that description. Terms that translate as simply "fiery" or "burning" don't convince me of a perceived red tint either, as fire would have been a common referent for brightness and light sources in those days, along with the sun and a very few other things. There is also the then common perception that Sirius caused excessive heat and dryness (the "dog days"), making fire metaphors almost unavoidable.


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deSitter
Still in Old School


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Re: The Red Sirius new [Re: David Knisely]
      #3408404 - 10/24/09 03:21 PM

Excellent point!

-drl

Quote:

Quote:

Again I would point out the simple calculation of the apparent brightness of say Betelgeuse or Antares at the distance of Sirius, roughly 100 times closer than either. The laws of light propagation show that the surface brightness does not change with distance - now something that is 100 times closer will have 100^2 or 10,000 times the area as something of the same physical size at the original distance - assuming that each part of the star shines with the same brightness (more or less, discounting fall-off at the limb) then moving a star 100 times closer means making it 10,000 times brighter - now 5 magnitudes is a factor of 100, so we're talking about a magnitude difference of 10 - Betelgeuse at the distance of Sirius would be magnitude -10 roughly, more than 100 times brighter than Venus - it would cast shadows at night and be visible in daylight without any effort. So there is not really any possibility that Sirius-B or any other nearby star was a red giant in historical time.

-drl




The current mass of the Sirius-B white dwarf is on the order of one solar mass. This points to an original mass of around five solar masses for the star prior to its white dwarf stage, so any red giant phase star would not have had nearly the intrinsic brightness of red giants like Betelgeuse (at least 18 solar masses) or Antares (15 to 18 solar masses). The absolute magnitude of a five solar mass red giant would probably be in the -3 to -4 range depending on exactly where the star was in its red giant stage. At the distance of Sirius, that would make the giant a visual magnitude of between roughly -7.6 and -8.6 even without including the contribution of Sirius A itself. It would shine far brighter than Venus does and might be roughly comparable to the brightness of a first-quarter moon. Clear skies to you.




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Hipparchus
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Re: The Red Sirius new [Re: deSitter]
      #3408547 - 10/24/09 04:54 PM

Interesting discussion.

During this time period, are there any references outside the Mediterranean to Sirius being red? Seems significant.


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Crossen
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Re: The Red Sirius new [Re: Hipparchus]
      #3409385 - 10/25/09 05:01 AM

Marcus Manilius and his "Astronomicon" have been mentioned in several recent posts. I decided not to use him for a couple reasons, one being exactly what Jim mentioned: Manilius is a rather shadowy figure about whom little is known, so it is hard to judge whether or not he was an active observer.

The relevant passage in Manilius about the redness of Sirius is in Book V, lines 207-8:

Exoriturque Canis, latratque Canicula flammens,/ Et rabit igne suo, geminatque incendia Solis.

This speaks of the rising Dog as "flaming vehemently, raging in its fire, and duplicating the fires of the Sun." Since this is explicitly about the rising Sirius, it cannot be taken as necessarily the star's color when it is well above the horizon.

A letter discussing the original Latin of Manilius' statements regarding the color of Sirius was published in "The Observatory" magazine in 1989 (vol. 109, p.58f.) It can be most easily found by simply Googling "Manilius Sirius."

One later Roman astrological writer, Maternus Julius Firmicus of the early 4th century BC, seems to have been familiar with Manilius' "Astronomicon," though he mentions neither explicitly. In "Matheseseos" VIII 12, 3f, Firmicus states that the constellation of Haedus ("Goat Kid"), rises simultaneously with Libra. This repeats "Astronomicon" V 311f, which is the only other place in Classical astrological or astronomical literature where the constellation "Haedus" is mentioned. (It's not merely a confusion for the Haedi, "Goat Kids," of Auriga, which did not then, and do not today, rise anywhere nearly simultaneously with Libra.)

In response to Hipparchus' question: The only possible ancient references to the color of Sirius outside of the Graeco-Roman world of which I am aware are those from Mesopotamia I mention in the article, which can be doubted on the basis of the fact that they are metaphors more than direct statements. However, the ancient Mesopotamians were careful and consistent about their religious metaphors. Red was the color of the war-god and the stage of Nebuchadnezzar's ziggurat dedicated to the planet of the war-god was faced with red-glazed baked bricks. It's easy to underestimate the ancient Mesopotamians given how fragmentary our information about them really is. The fact we find the Pythagorean Theorem used on an Old Babylonian tablet of about 1700 BC hints at their intellectual discipline.

Craig Crossen


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Tony Flanders
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Re: The Red Sirius new [Re: Crossen]
      #3409468 - 10/25/09 07:57 AM

Quote:

One of the most important aspects of the question of an ancient red Sirius is the intellectual sophistication of the ancient authorities who report Sirius as red. These were neither credulous nor gullible men. The genius of Ptolemy is beyond dispute ...




Yes, anybody who's read Ptolemy has to be aware of Ptolemy's incredible mastery of his material and his mathematical sophistication.

But not gullible? I beg to differ! Remember, Ptolemy is also the man who established the underpinnings of astrology as we now know it. And defended it by arguments that were as feeble then as they seem when repeated now.

I still think that cultural conformity is overwhelmingly the most likely explanation of Sirius's redness. Ptolemy, being tapped into the astronomical tradition root and branch, is the *most* likely person to have taken such traditions for granted.

Expectations have an overwhelming influence on observations. History is rife with examples of blatantly incorrect observations that were passed down unquestioned for centuries. Nobody can escape the assumptions of the surrounding society. We are *all* gullible -- it's part of human nature.

So I'd say that odds are easily 10 to 1 that modern astrophysics is right and those ancient descriptions were wrong. But yes, that lingering 1-out-of-10 doubt is bound to remain.

Edited by Tony Flanders (10/25/09 08:01 AM)


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deSitter
Still in Old School


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Re: The Red Sirius new [Re: Tony Flanders]
      #3409476 - 10/25/09 08:08 AM

I have another theory. These folks had one source of man-made illumination - fire. They had no white light other than sunlight to compare anything to. Using the word "fiery" could have been literal - they no doubt assumed that the light was coming from some sort of cosmic fire, which could very well sway their description and even their perception of it. (Who was it who called the Sun "a fiery rock as big as the Peloponnessus"?)

-drl


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Starman1
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Re: The Red Sirius new [Re: deSitter]
      #3409718 - 10/25/09 11:15 AM

And, of course, we know that the descriptions of antiquity were wrong, because there is no physical way they could have been right.

Because any insinuation that their descriptions were physically true suffer from an inability to explain any rational physical process whereby they would be true.

Having studied ancient cultures extensively (I have a degree in Anthropology), I would simply state that the explanation for the descriptions about which the discussion pivots is not in physical reality. We are merely looking for cultural and intellectual reasons why they might have used the words they used to describe a star which was a Class A star even then.


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jrbarnett
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Re: The Red Sirius new [Re: Crossen]
      #3409848 - 10/25/09 12:20 PM

The interesting part (to me at least) isn't that the ancient accounts were wrong,but rather trying to figure out whether there is a common source or cause for them being wrong. I'm wondering if Sirius wasn't red "by tradition". I'll explain.

I'm wondering in particular about Egyptian texts. After all, Sirius played a central role in Egyptian religious life (and agriculture). The "Sothic Cycle" was measured by priestly abservations of the heliacal rising of Sirius (that is the rising of Sirius immediately prior to the sunrise). In fact, I recall reading somewhere that different predictions for the coming year were based on the star's apparent color at the helical rising. Red foretold war in the coming year.

Is it possible that the tradition of a red Sirius is really a concept imported into Western Hellenic culture via imported traditions from ancient Egypt? That is, knowing that associations of red with the star were "important" to more ancient cultures, but losing the context (heliacal rising) in the mists of time.

Many of our modern "sayings" come about this way. The original context long forgotten, but the saying itself remains, taking on a more literal application.

Regards,

Jim

Edited by jrbarnett (10/25/09 12:24 PM)


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Starman1
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Re: The Red Sirius new [Re: jrbarnett]
      #3410058 - 10/25/09 02:07 PM

To back up Jim, Sirius is referred to as "The Dog Star" and the hottest days of summer, the "Dog Days" of summer, occur in early July, when Sirius is rising in the east at dawn. This also corresponded to the time of the annual flooding of the Nile, so people living in low areas would pack up and head for higher ground.
The Greeks and Romans traded extensively with the Egyptians, and many things were borrowed. After all, Ptolemy was an Egyptian.


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