APOD: The Star Streams of NGC 5907 (2008 Jun 19)

[bystander]

What's missing is why the 'missing' companion galaxies are so accepted as having been there in the first place. The 'evidence' is pure speculation, but I am disappointed that the 'missing' galaxies are so present in the minds of most of you as to disallow any real speculation of the possiblility that the existing galaxy created the trails. However, I am satisfied that my initial observation of the possibility of a tumbling galaxy has been credited as being at least possible .. although I am certain it is a fact.

The evidence of the missing galaxies is the tidal streams of stars which were the point of the apod.

More Tidal Streams

APOD: 2008 February 7 - NGC 4013 and the Tidal Stream
APOD: 2007 November 4 - The Closest Galaxy: Canis Major Dwarf
APOD: 2005 May 29 - The Sagittarius Dwarf Tidal Stream

Would a scientist here please explain the scientific meaning of "working hypothesis"? Please and thank you.

Hypothesis - A tentative conjecture explaining an observation, phenomenon, or scientific problem that can be tested by further observation, investigation, and/or experimentation.

Conjecture - A statement likely to be true based on available evidence, but which has not been formally proven.

A working hypothesis is simply the hypothesis under scrutiny, or being tested. It is not "pure speculation" but a reasoned observation based upon the evidence available. Hypotheses must be testable (refutable, falsifiable). See Scientific Method.

[Sputnick]

If I were in space, and hurled a spinnng gyroscope in such a way that I caused it to tumble as it flew, I make a guess that it's anybody's guess as to when it becomes "free falling".

I don't think it quite works like that. You can't "set a gyroscope tumbling" without applying a constant torque, unless I've completely forgotten how angular momentum works...

Do you mean to tell me that if I threw a Gyroscope it space, using my
fingers to spin the whole assembly against the spin of the wheel, that the gyroscope would not tumble? the Physics of space must be totally different then the physics in our atmosphere. I'm not talking about an eternal tumble here .. just for the length of time physics would set. Everything comes to an end .. even time "There shall be time no more" - Revelation.

[Sputnick]

What's missing is why the 'missing' companion galaxies are so accepted as having been there in the first place. The 'evidence' is pure speculation, but I am disappointed that the 'missing' galaxies are so present in the minds of most of you as to disallow any real speculation of the possiblility that the existing galaxy created the trails. However, I am satisfied that my initial observation of the possibility of a tumbling galaxy has been credited as being at least possible .. although I am certain it is a fact.

The evidence of the missing galaxies is the tidal streams of stars which were the point of the apod.

Sorry to have to use the word 'nonsense' Bystander .. but most contributors have said the companion galaxies are speculation,
their disappearance being a huge question mark.

More Tidal Streams

APOD: 2008 February 7 - NGC 4013 and the Tidal Stream
APOD: 2007 November 4 - The Closest Galaxy: Canis Major Dwarf
APOD: 2005 May 29 - The Sagittarius Dwarf Tidal Stream

Would a scientist here please explain the scientific meaning of "working hypothesis"? Please and thank you.

Hypothesis - A tentative conjecture explaining an observation, phenomenon, or scientific problem that can be tested by further observation, investigation, and/or experimentation.

Conjecture - A statement likely to be true based on available evidence, but which has not been formally proven.

A working hypothesis is simply the hypothesis under scrutiny, or being tested. It is not "pure speculation" but a reasoned observation based upon the evidence available. Hypotheses must be testable (refutable, falsifiable). See Scientific Method.

Thank you .. the language says the same thing .. possibilities.

[bystander]

APOD: 2008 June 19 - The Star Streams of NGC 5907

The evidence of the missing galaxies is the tidal streams of stars which were the point of the apod.

More Tidal Streams

APOD: 2008 February 7 - NGC 4013 and the Tidal Stream
APOD: 2007 November 4 - The Closest Galaxy: Canis Major Dwarf
APOD: 2005 May 29 - The Sagittarius Dwarf Tidal Stream

Sorry to have to use the word 'nonsense' Bystander .. but most contributors have said the companion galaxies are speculation, their disappearance being a huge question mark.

I think "most contributors" would take exception to that statement. The currently accepted explanation for tidal streams is that they are the remnant of galaxies that are being (or have been) ripped apart and absorbed by a larger, more massive, galaxy. See the above links. The only "nonsense" is calling the considered opinion of mainstream astrophysicists "nonsense".

Here's another: APOD: 2002 October 17 - Centaurus A: Young Blue Star Stream

[henk21cm]

Does anyone know what the blurred object in the upper right-hand corner is? It could be "just" another galaxy, but it doesn't look like it would be one.

On first sight, yes, galaxy, since it is not shaped as a point. On second thought, the shape is rather weird. It resembles a shoe, seen from the long side. The right back end of the trail is thicker than the left upper end, which curls upwards.

When compared with other non circular shapes, e.g. near the tidal stream itself, at the right side, close to the extremely bright star right below, these objects are more regularly shaped.

Since the image is taken in Draco, it is unlikely to be an astroid, which moved during the exposure with respect to the stars.

[Sputnick]

APOD: 2008 June 19 - The Star Streams of NGC 5907

The evidence of the missing galaxies is the tidal streams of stars which were the point of the apod.

More Tidal Streams

APOD: 2008 February 7 - NGC 4013 and the Tidal Stream
APOD: 2007 November 4 - The Closest Galaxy: Canis Major Dwarf
APOD: 2005 May 29 - The Sagittarius Dwarf Tidal Stream

Sorry to have to use the word 'nonsense' Bystander .. but most contributors have said the companion galaxies are speculation, their disappearance being a huge question mark.

I think "most contributors" would take exception to that statement. The currently accepted explanation for tidal streams is that they are the remnant of galaxies that are being (or have been) ripped apart and absorbed by a larger, more massive, galaxy. See the above links. The only "nonsense" is calling the considered opinion of mainstream astrophysicists "nonsense".

Here's another: APOD: 2002 October 17 - Centaurus A: Young Blue Star Stream

Since we're talking nonsense .. (and I apologize for my rudeness, but I've been under the stresses of the universes tugging at my heart in every direction and anti-direction) no more talking nonsense .. we are not talking about tidal streams other than the tidal streams we are talking about .. the streams in this particular photograph which shows to rare phenomenon pictured together .. the streams which contributors here have said may be (and I stress 'may be') from companion galaxies, but that supporting evidence for the missing galaxies does not seem to exist. And while someone may say they may be hiding behind or in the pictured galaxy, I say they are/were pure fiction, never having existed, and that the pictured galaxy created the trails, and that the trails are the missing bulk of the pictured galaxy. Period. End of response except to say thank you for not being as rude to me as I was to you.

[iampete]

Since we're talking nonsense ..

My 2 cents on "nonsense".

Pejorative labels are unhelpful in any discussion.

I believe that the consensus is that there exists a mechanism to account for the streams and that mechanism is a companion galaxy. Manifestations of similar streams around other galaxies and companions are supportive evidence. Possible angular momentum changes caused by the ingestion of a companion galaxy may be further evidence, although no one else has signed up for that one yet. Possible explanations as to why a companion galaxy is not visible in this view appear to have reasonable basis, although they are certainly not inarguable. To call this "nonsense" is unwarranted.

Your belief of stream creation by the galaxy itself without a companion galaxy has not been refuted as being impossible by any mechanism we know about. However, to this point, there does not seem to be any evidence of which I am aware that supports this. Nevertheless, until someone is able to rule it out, calling your belief "nonsense" is also unwarranted.

In matters of opinion and conjecture, especially on a forum like this, words like "nonsense" should be reserved for statements (EDIT: that) have been or can be unequivocally debunked as false, e.g., a flat earth, a geocentric solar system, and similar thoughts. Use of descriptors such as possible, likely (highly, more, less, un-), supported/unsupported by evidence, etc., etc. will result in this forum being more about discussions than confrontations.

My apologies for sounding preachy.

[Sputnick]

Since we're talking nonsense ..

My 2 cents on "nonsense".

Pejorative labels are unhelpful in any discussion.

I believe that the consensus is that there exists a mechanism to account for the streams and that mechanism is a companion galaxy. Manifestations of similar streams around other galaxies and companions are supportive evidence. Possible angular momentum changes caused by the ingestion of a companion galaxy may be further evidence, although no one else has signed up for that one yet. Possible explanations as to why a companion galaxy is not visible in this view appear to have reasonable basis, although they are certainly not inarguable. To call this "nonsense" is unwarranted.

Your belief of stream creation by the galaxy itself without a companion galaxy has not been refuted as being impossible by any mechanism we know about. However, to this point, there does not seem to be any evidence of which I am aware that supports this. Nevertheless, until someone is able to rule it out, calling your belief "nonsense" is also unwarranted.

In matters of opinion and conjecture, especially on a forum like this, words like "nonsense" should be reserved for statements (EDIT: that) have been or can be unequivocally debunked as false, e.g., a flat earth, a geocentric solar system, and similar thoughts. Use of descriptors such as possible, likely (highly, more, less, un-), supported/unsupported by evidence, etc., etc. will result in this forum being more about discussions than confrontations.

My apologies for sounding preachy.

Exactly, nonsense is nonsense, and I apologized, and I think it's nonsense that the offense was further furthered (just speaking nonsense here .. whimsical humour, nonsensical.)

However, I take exception to ignoring of the statements which make the total vanishing act of the supposed companion galaxies, shall we say, extremely perplexing, unexplainable, highly suspect. I cannot provide any quotes, but they are there. There is and seems to always have been among scientists an acceptance and promotion of the easy explanation which leads to lack of serious pursuit of less attractive options .. partly because we as humans enjoy the companionship of our peers, and we don't want to be ejected for rocking the boat. This is a sad situation, and were it not reinforced, our flat earth might not have become surrounded by an orbiting garbage dump resulting from our attempts to reach and understand space. Ye are not the only preacher here, Iampete.

[astrolabe]

Hello All,

In the interest of this topic and maybe to others similar to it, there is going to be a workshop/seminar in Padova, Italy on Aug. 25-28 this year to discuss what are called "non-axisymmetrical phenomenon in galaxies".

The workshop intends to bring together ideas and the measurements of the different methods used in the past 20 years to determine rates of pattern speed and rotation of different shaped galaxies as well as dark halos.

The workshop is titled: "Tumbling, Twisting, and Winding Galaxies: Pattern Speeds Along the Hubble Sequence". I'll be interested to see what the theorists come up with.

[BMAONE23]

Looking at the full image for location http://antwrp.gsfc.nasa.gov/apod/ap080619.html, then the enlarged image for clarity, it appears that there is a small Hand shaped asterism at about the 11:00 position consisting of 5 small stars (the fingertips) and an ovid shape in the palm. Perhaps the ovid shape is the remnant galactic core of the canibalized galaxy. It does fall within the center of one of the star trails.

[Qev]

If I were in space, and hurled a spinnng gyroscope in such a way that I caused it to tumble as it flew, I make a guess that it's anybody's guess as to when it becomes "free falling".

I don't think it quite works like that. You can't "set a gyroscope tumbling" without applying a constant torque, unless I've completely forgotten how angular momentum works...

Do you mean to tell me that if I threw a Gyroscope it space, using my
fingers to spin the whole assembly against the spin of the wheel, that the gyroscope would not tumble?

Yes, that's correct. Angular momentum has to be conserved, and it's a vector quantity... direction counts. You can apply a force (torque, actually) to alter the orientation of a gyroscope's rotational axis, but the instant you stop applying that torque, it's going to remain in whatever its last orientation was (in addition to other effects).

[Sputnick]

Hello All,

In the interest of this topic and maybe to others similar to it, there is going to be a workshop/seminar in Padova, Italy on Aug. 25-28 this year to discuss what are called "non-axisymmetrical phenomenon in galaxies".

The workshop intends to bring together ideas and the measurements of the different methods used in the past 20 years to determine rates of pattern speed and rotation of different shaped galaxies as well as dark halos.

The workshop is titled: "Tumbling, Twisting, and Winding Galaxies: Pattern Speeds Along the Hubble Sequence". I'll be interested to see what the theorists come up with.

Ahh .. I should let them know that if they were willing to pay expenses I would appear as a speaker. I've always wanted to visit Italy, and I could take my moped and camping gear, sleep out under the stars and watch the galaxies tumble .. maybe tumble with Sophia Loren .. Ahhhhh. (I hope she's still alive.)

[henk21cm]

Yes, that's correct. Angular momentum has to be conserved, and it's a vector quantity... direction counts.

There is a anecdote about a gyroscope and Jean Perrin. I read the story as a younster in a book by George Gamov. The nice illustration in Gamovs book lacks in the following quote.

<< Quote: Another trick perpetrated in the French capital was due to the physicist Jean Perrin (who won a year later the 1926 Nobel Prize for his work on the thermal motion of molecules). Perrin mischievously packed a powerful aviation gyroscope into a suitcase, set the gyro spinning and left the suitcase at a Paris railway station. An unsuspecting porter picked up the apparently forgotten luggage, marched off with it and then made the mistake of trying to turn a corner. The case – or, rather, its contents – refused to follow. When the porter attempted to force the unwilling bag to point in the new direction he wanted to travel, it simply rotated on its handle at a bizarre angle and twisted the bewildered man's wrist. Dropping his strange load in alarm, the porter ran off yelling "Le diable soi-même doit être la dedans!" (The Devil himself must be inside!) :etouQ>>

[Sputnick]

<< Quote: Another trick perpetrated in the French capital was due to the physicist Jean Perrin (who won a year later the 1926 Nobel Prize for his work on the thermal motion of molecules). Perrin mischievously packed a powerful aviation gyroscope into a suitcase, set the gyro spinning and left the suitcase at a Paris railway station. An unsuspecting porter picked up the apparently forgotten luggage, marched off with it and then made the mistake of trying to turn a corner. The case – or, rather, its contents – refused to follow. When the porter attempted to force the unwilling bag to point in the new direction he wanted to travel, it simply rotated on its handle at a bizarre angle and twisted the bewildered man's wrist. Dropping his strange load in alarm, the porter ran off yelling "Le diable soi-même doit être la dedans!" (The Devil himself must be inside!) :etouQ>>[/quote]

So that's why my head can't change direction easily .. I'm spinny!