Astronomy XXX

[reerer]

Modern astronomers use parallax to determine the distance to a star. Parallax is based on the stars of the stellar universe that are stationary where the change in the angular position of a stationary star is measured after the observed on the earth propagates the distance of the earth's orbital diameter (six months) but the distance to a 4.22 light year (4 x 10^16 meters) star is more than 10^7 times larger than the earth's orbital diameter (1.4 x 10^10 m); consequently, the parallax reference distance of the earth's orbital distance is to short of a distance to produce a change in the angular position of a stationary 4.22 ly star using the Hubble that has a resolution of .1 arcsec.

 

[John Cuthber]

You have demonstrated that other techniques must also be used.

Well spotted.

Here's a link to some of the other ways we measure stellar distance

http://www.ast.cam.ac.uk/~mjp/

 

 

[beecee]

1 hour ago, reerer said:

Modern astronomers use parallax to determine the distance to a star. Parallax is based on the stars of the stellar universe that are stationary where the change in the angular position of a stationary star is measured after the observed on the earth propagates the distance of the earth's orbital diameter (six months) but the distance to a 4.22 light year (4 x 10^16 meters) star is more than 10^7 times larger than the earth's orbital diameter (1.4 x 10^10 m); consequently, the parallax reference distance of the earth's orbital distance is to short of a distance to produce a change in the angular position of a stationary 4.22 ly star using the Hubble that has a resolution of .1 arcsec.

 

Good work! The Parallax or triangulation method though is limited to around stellar objects with about 500 L/years. Beyond that cosmologists/astronomers use various other methods.

[1] Colour and apparent magnitude or brightness. See the  "Hertzsprung- Russell diagram" for more information, if you are really interested.

(2) Cepheid Variables: These are stars that brighten and dim periodically: The brighter they are,  the longer the period to dimming and then brightening again. Thus their brightness can be reasonably accurately inferred. Again if you are truly interested in this fascinating methodology see  https://en.wikipedia.org/wiki/Cepheid_variable

(3) Type 1a Supernova: These are White Dwarfs in binary systems. Briefly a White Dwarf has a set mass and when and if it sucks off mass from its companion star, will go supernova, and based on the set mass, and magnitude of the supernova, can be used as standard candles. Again if your interest is genuine then see...https://en.wikipedia.org/wiki/Type_Ia_supernovaIn 

 

It must be remembered though that distances between objects in the universe are constantly changing, due to the expansion of the universe as evidenced with cosmological redshift. The following is informative in that regard.....http://www.astro.ufl.edu/~guzman/ast7939/projects/project01.html

 

I hope that helps. 

Edited October 26, 2017 by beecee

[Strange]

7 minutes ago, beecee said:

The Parallax or triangulation method though is limited to around stellar objects with about 500 L/years.

It can go much further than that:

Quote

The Hubble telescope WFC3 now has the potential to provide a precision of 20 to 40 microarcseconds, enabling reliable distance measurements up to 5,000 parsecs (20,000 ly) for small numbers of stars.^[4][5] 

https://en.wikipedia.org/wiki/Cosmic_distance_ladder

But I wouldn't expect much sensible response from the OP. He appears to have copied this from someone who was trolling another science forum. I doubt he even understands most of the words he copies and pastes.

[Janus]

2 hours ago, reerer said:

Modern astronomers use parallax to determine the distance to a star. Parallax is based on the stars of the stellar universe that are stationary where the change in the angular position of a stationary star is measured after the observed on the earth propagates the distance of the earth's orbital diameter (six months) but the distance to a 4.22 light year (4 x 10^16 meters) star is more than 10^7 times larger than the earth's orbital diameter (1.4 x 10^10 m); consequently, the parallax reference distance of the earth's orbital distance is to short of a distance to produce a change in the angular position of a stationary 4.22 ly star using the Hubble that has a resolution of .1 arcsec.

 

1. The distance you give for the Earth orbital diameter is off by a factor of 21.  To 2 significant digits, the radius is 1.5 x10¹¹ meters, the diameter is twice that.

2. The Earth's orbital diameter divided by  by 4.22 ly gives 0.0000075.  The arc tangent of which is 0.0043 degrees or 1.55 arc seconds, 15 times larger than the Hubble resolution, more than enough to be measured.

 

 

[beecee]

1 hour ago, Strange said:

It can go much further than that:

Yep, OK, but I would imagine as distances get further, other methodologies are more preferred?

 

Quote

 

https://en.wikipedia.org/wiki/Cosmic_distance_ladder

But I wouldn't expect much sensible response from the OP. He appears to have copied this from someone who was trolling another science forum. I doubt he even understands most of the words he copies and pastes.

 

As is evident in a couple of threads started by the same person.

[Strange]

3 minutes ago, beecee said:

Yep, OK, but I would imagine as distances get further, other methodologies are more preferred?

Indeed. But you need some overlap between the various methods to build a reliable distance ladder.

[pzkpfw]

(Banned or suspended from: physicsforums.com https://www.physicsforums.com/threads/does-modern-astronomy-have-a-problem.929551/ )
 

[T. McGrath]

1 hour ago, beecee said:

Good work! The Parallax or triangulation method though is limited to around stellar objects with about 500 L/years. Beyond that cosmologists/astronomers use various other methods.

[1] Colour and apparent magnitude or brightness. See the  "Hertzsprung- Russell diagram" for more information, if you are really interested.

(2) Cepheid Variables: These are stars that brighten and dim periodically: The brighter they are,  the longer the period to dimming and then brightening again. Thus their brightness can be reasonably accurately inferred. Again if you are truly interested in this fascinating methodology see  https://en.wikipedia.org/wiki/Cepheid_variable

(3) Type 1a Supernova: These are White Dwarfs in binary systems. Briefly a White Dwarf has a set mass and when and if it sucks off mass from its companion star, will go supernova, and based on the set mass, and magnitude of the supernova, can be used as standard candles. Again if your interest is genuine then see...https://en.wikipedia.org/wiki/Type_Ia_supernovaIn 

 

It must be remembered though that distances between objects in the universe are constantly changing, due to the expansion of the universe as evidenced with cosmological redshift. The following is informative in that regard.....http://www.astro.ufl.edu/~guzman/ast7939/projects/project01.html

 

I hope that helps. 

Parallax is without a doubt the most accurate means of measuring cosmological distances, but as you correctly pointed out, it does have its limitations.

Beyond parallax the methods used to measure distance becomes less reliable.  Classical Cepheid variables are perhaps the second best source for measuring distance, providing you can distinguish them from anomalous Cepheid variables, RR Lyrae variables, or double-mode Cepheid variables.  That should get you out to just about a million parsecs.

Beyond about a million parsecs there is only two methods used to measure cosmological distances, Type Ia SNe and red-shift.  Both have issues.  Red-shift is great for determining how fast an object is moving relative to us, but not so good for determining distances except in the most general terms.

Back in the 1990s we use to think the Type Ia SNe was our "Standard Candle," with a peak absolute magnitude of -19.46.  However, we have since discovered "superluminous" Type Ia SNe in 2006 and subsequently, and we developed a whole new classification of supernovae in 2013 - Type Iax.  Furthermore, there is between 18% and 48% chance that those supernovae that were classified Type Ia SNe prior to 2013 are in error and should actually be the much dimmer Type Iax SNe.  Which brings into question not just the age of the universe but the existence of Dark Energy and this whole "acceleration" process.  Dark Energy could simply be a mistake based upon our erroneous assumption that all Type Ia SNe were the same.  The exact same mistake Edwin Hubble made in 1927 when he attempted to calculate the age of the universe using Cepheid variables as his "Standard Candle."

 

[beecee]

1 hour ago, pzkpfw said:

(Banned or suspended from: physicsforums.com https://www.physicsforums.com/threads/does-modern-astronomy-have-a-problem.929551/ )
 

Interesting...one could not be blamed for thinking this is one of those common garden  variety, anti science trolls. 

1 hour ago, T. McGrath said:

Parallax is without a doubt the most accurate means of measuring cosmological distances, but as you correctly pointed out, it does have its limitations.

Beyond parallax the methods used to measure distance becomes less reliable.  Classical Cepheid variables are perhaps the second best source for measuring distance, providing you can distinguish them from anomalous Cepheid variables, RR Lyrae variables, or double-mode Cepheid variables.  That should get you out to just about a million parsecs.

Beyond about a million parsecs there is only two methods used to measure cosmological distances, Type Ia SNe and red-shift.  Both have issues.  Red-shift is great for determining how fast an object is moving relative to us, but not so good for determining distances except in the most general terms.

Back in the 1990s we use to think the Type Ia SNe was our "Standard Candle," with a peak absolute magnitude of -19.46.  However, we have since discovered "superluminous" Type Ia SNe in 2006 and subsequently, and we developed a whole new classification of supernovae in 2013 - Type Iax.  Furthermore, there is between 18% and 48% chance that those supernovae that were classified Type Ia SNe prior to 2013 are in error and should actually be the much dimmer Type Iax SNe.  Which brings into question not just the age of the universe but the existence of Dark Energy and this whole "acceleration" process.  Dark Energy could simply be a mistake based upon our erroneous assumption that all Type Ia SNe were the same.  The exact same mistake Edwin Hubble made in 1927 when he attempted to calculate the age of the universe using Cepheid variables as his "Standard Candle."

 

Nice summary. I'm pretty sure most people, even lay people would realize that when speaking of large cosmic distances millions and billions of L/years, that large error bars would accompany those. I also remember reading a report re "superluminous" Type 1a, but havn't heard much since.

The DE component certainly is still being debated, particularly as to its nature, but to my lay person's mind, it seems a rather reasonable process, and the interesting point that the acceleration stage started around 5 billion years ago.

Edited October 27, 2017 by beecee

[T. McGrath]

1 hour ago, beecee said:

Interesting...one could not be blamed for thinking this is one of those common garden  variety, anti science trolls. 

Nice summary. I'm pretty sure most people, even lay people would realize that when speaking of large cosmic distances millions and billions of L/years, that large error bars would accompany those. I also remember reading a report re "superluminous" Type 1a, but havn't heard much since.

The DE component certainly is still being debated, particularly as to its nature, but to my lay person's mind, it seems a rather reasonable process, and the interesting point that the acceleration stage started around 5 billion years ago.

Superluminous SNe have been measured with an absolute magnitude of -23, 50 times brighter than your typical Type Ia SNe, but they are much rarer than the "sub-Chandrasekhar" Type Iax SNe.  Superluminous Type Ia would throw off our distance by making it appear closer than it really is, which does not appear to be our problem.  Our issue with an accelerating universe is because these so-called Type Ia SNe are appearing further away than they should.  Which would be the result if you were looking at a Type Iax SNe with an absolute magnitude of -14.2 but calculated its distance based upon an absolute magnitude of -19.46.

We can distinguish the difference between Type Ia SNe and Type Iax SNe, but only with sufficient data.  We need more than just the light-curve.  A full spectrum is required, for example, in order to determine the velocity of the SNe ejecta.  The ejecta of all Type Iax SNe is less than 10,000 kps, while the ejecta of all Type Ia SNe exceeds 10,000 kps.  There are additional ways the two different SNe can be distinguished, but only if we have the data.  Unfortunately in many cases astronomers only obtain the light-curve and no spectrum, then make an assumption based upon that light-curve and its red-shift on the type of SNe it can be.

I'm not sure if there is a means to distinguish the difference between a "Super-Chandrasekhar" superluminous Type Ia SNe and a normal Type Ia SNe.  There has been some suggestions that these superluminous Type Ia SNe are the result of the rapid spin rate of the progenitor.  While that makes sense, I am not sure how we would be able to determine the rotation of the progenitor after the fact.

Sources:
'Super-Chandrasekhar' Type Ia Supernovae at Nebular Epochs - Monthly Notices of the Royal Astronomical Society, Volume 432, Issue 4, 11 July 2013, Pages 3117–3130
Superluminous Supernovae at Redshifts of 2.05 and 3.90 - Nature 491, Pages 228–231, November 2012 (free preprint)
Type Iax Supernovae: A New Class of Stellar Explosion - The Astronomical Journal, Volume 767, Number 1, March 25, 2013
Gone in a flash: Supernovae in the survey era - Astronomy & Geophysics, Volume 54, Issue 6, Pages 6.17–6.21, December 2013
A Luminous Peculiar Type Ia Supernova SN 2011hr: More Like SN 1991T or SN2007if? - arXiv 1512.03995, January 2016

 

Edited October 27, 2017 by T. McGrath

[John Cuthber]

What's the resolution like on radio telescope arrays these days?

[beecee]

9 hours ago, T. McGrath said:

Superluminous SNe have been measured with an absolute magnitude of -23, 50 times brighter than your typical Type Ia SNe, but they are much rarer than the "sub-Chandrasekhar" Type Iax SNe.  Superluminous Type Ia would throw off our distance by making it appear closer than it really is, which does not appear to be our problem.  Our issue with an accelerating universe is because these so-called Type Ia SNe are appearing further away than they should.  Which would be the result if you were looking at a Type Iax SNe with an absolute magnitude of -14.2 but calculated its distance based upon an absolute magnitude of -19.46.

We can distinguish the difference between Type Ia SNe and Type Iax SNe, but only with sufficient data.  We need more than just the light-curve.  A full spectrum is required, for example, in order to determine the velocity of the SNe ejecta.  The ejecta of all Type Iax SNe is less than 10,000 kps, while the ejecta of all Type Ia SNe exceeds 10,000 kps.  There are additional ways the two different SNe can be distinguished, but only if we have the data.  Unfortunately in many cases astronomers only obtain the light-curve and no spectrum, then make an assumption based upon that light-curve and its red-shift on the type of SNe it can be.

I'm not sure if there is a means to distinguish the difference between a "Super-Chandrasekhar" superluminous Type Ia SNe and a normal Type Ia SNe.  There has been some suggestions that these superluminous Type Ia SNe are the result of the rapid spin rate of the progenitor.  While that makes sense, I am not sure how we would be able to determine the rotation of the progenitor after the fact.

Sources:
'Super-Chandrasekhar' Type Ia Supernovae at Nebular Epochs - Monthly Notices of the Royal Astronomical Society, Volume 432, Issue 4, 11 July 2013, Pages 3117–3130
Superluminous Supernovae at Redshifts of 2.05 and 3.90 - Nature 491, Pages 228–231, November 2012 (free preprint)
Type Iax Supernovae: A New Class of Stellar Explosion - The Astronomical Journal, Volume 767, Number 1, March 25, 2013
Gone in a flash: Supernovae in the survey era - Astronomy & Geophysics, Volume 54, Issue 6, Pages 6.17–6.21, December 2013
A Luminous Peculiar Type Ia Supernova SN 2011hr: More Like SN 1991T or SN2007if? - arXiv 1512.03995, January 2016

 

Interesting detailed summary...as I'm past my bed time I'll check your links in the morning.

[Janus]

22 hours ago, John Cuthber said:

What's the resolution like on radio telescope arrays these days?

The Very Large Array in New Mexico has a resolution of 0.2 arcseconds at the 3 cm wavelength.

[swansont]

On 10/26/2017 at 5:55 PM, Strange said:

 But I wouldn't expect much sensible response from the OP. He appears to have copied this from someone who was trolling another science forum. I doubt he even understands most of the words he copies and pastes.

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Moderator Note

Regardless, this sort of observation is off-topic.

 

On 10/26/2017 at 7:13 PM, pzkpfw said:

(Banned or suspended from: physicsforums.com https://www.physicsforums.com/threads/does-modern-astronomy-have-a-problem.929551/ )

!

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This is what should go in your comment to the staff when you report the post, rather than appearing in the thread.

 

[reerer]

  The resolution required to determine the distance to a 4.22 ly star is calculated using,

 

 

A/B = cos θ..............................................................................................................................111

 

 

where A is the earth orbital diameter, B is the distance to a 4.22 ly star and θ is the telescopic resolution which forms,

 

 

A/B = (1.4 x 10¹⁰ m) / (4 x 10¹⁶ meters) = 3.5 x 10^-7 degrees..................................................112

 

when A/B → 0,

 

 

A/B = θ......................................................................................................................................113

 

 

The resolution required to determine the distance to a 4.22 ly star is:

 

 

θ  = 3.5 x 10^-7 degree or .00126 arcsec....................................................................................114

 

 

To measure the distance of a 4.22 ly star using the earth's orbital diameter as the parallax reference distance requires a telescopic resolution of .00126 arcsec which is 79 times more powerful than the Hubble (.1 arcsec). The Hipparcos telescope is used to justify the measurement of the distance to a 4.22 light year star since the Hipparcos is described with a resolution of .001 arcsec but the Hubble's mirror diameter is 7.9 feet which is eight times larger than the Hipparacos mirror diameter (11 inches) yet the Hipparcos is 100 times more powerful than the Hubble which is not physically possible. I predict that the maximum resolution of an optical reflection telescope is .1 arcsec since the Webb has the resolution of .1 arcsec and has a mirror diameter of 21 feet. The most powerful telescope known to man is the Hubble. The maximum distance to a star calculated using the Hubble is,

 

 

A/θ = B = (1.4 x 10¹⁰ m) (3600) / (.1 arcsec) = .5.04 x 10¹⁴m = .05327 light years....................115

 

_________________________________________________________________________________________________________

 

Is my mathematics correct?

 

[Strange]

21 minutes ago, reerer said:

Is my mathematics correct?

Where did you copy it from?

Why does it start from equation 111?

Why do you have the wrong value for the diameter of the Earth's orbit?

31 minutes ago, reerer said:

yet the Hipparcos is 100 times more powerful than the Hubble which is not physically possible

So it is a choice between thousands of scientists, engineers and others being involved in some pointless conspiracy or you do not understand physics.

Given your posts here, it is pretty obvious which it is.

44 minutes ago, reerer said:

To measure the distance of a 4.22 ly star using the earth's orbital diameter as the parallax reference distance requires a telescopic resolution of .00126 arcsec which is 79 times more powerful than the Hubble (.1 arcsec).

Wrong on two counts:

1. As noted your baseline is out by a factor of 20. (Your were told this before and you haven't corrected it.)

2. The resolution of Hubble is much greater than that: "The Hubble telescope WFC3 now has the potential to provide a precision of 20 to 40 microarcseconds" (The Hubble telescope WFC3 now has the potential to provide a precision of 20 to 40 microarcseconds). You have been told this before as well.

 

[Janus]

1 hour ago, reerer said:

  The resolution required to determine the distance to a 4.22 ly star is calculated using,

 

 

A/B = cos θ..............................................................................................................................111

 

 

where A is the earth orbital diameter, B is the distance to a 4.22 ly star and θ is the telescopic resolution which forms,

 

 

A/B = (1.4 x 10¹⁰ m) / (4 x 10¹⁶ meters) = 3.5 x 10^-7 degrees..................................................112

 

when A/B → 0,

 

 

A/B = θ......................................................................................................................................113

 

 

The resolution required to determine the distance to a 4.22 ly star is:

 

 

θ  = 3.5 x 10^-7 degree or .00126 arcsec....................................................................................114

 

 

 

 

 

_________________________________________________________________________________________________________

 

Is my mathematics correct?
 

 

No.

1. The radius of the Earth's orbit (as I've already pointed out) is 1.5 x 11 meters or ~10.5 times larger than the figure you gave.

2.  You wouldn't use cos, because is  the ratio of the adjacent side to the hypotenuse, and we are dealing the two sides of the triangle that are not the hypotenuse, and thus you need to use tan instead. 

3.  Your description of the relationship between the trig function and angle is wrong.  While the cos of theta is equal to  the length of the adjacent side divided by the hypotenuse, this ratio does not equal theta or any angle.  For example, the cos of 45 degrees  is 0.7071...  Which means that the the length of the adjacent side divided by the hypotenuse equals 0.7071... not 45. The tan of 45 degrees = 1, which makes the opposite and adjacent sides equal in length for a right angle triangle with two 45 degree angles. 

In fact, cos theta can only range between -1 and 1 no matter what angle theta is equal to.

To get the angle from the ratio of two sides, you have to take the inverse trig function of the ratio of the sides. (in the old days you would use a table, but today you use the cos-1, sin-1 or tan-1 function on a calculator. The other names for these are the arccos, arcsin, and arctan.)

To sum up, using the correct orbital radius, 1.5 x 1011 meters, divided by the distance of 4 x 10^16 meters gives 0.00000375.

The inverse tangent of which is 0.000215 degrees (another reason you wouldn't use cos here is that the inverse cos of  0.00000375 is 89.99985 degrees)

0.000215 degrees is 0.7735 arcsec.

However, 1.5 x 1011 is the radius of the Earth's orbit, and the actual measurement is made over the diameter, and will be twice as large . (Listed parallaxes are always listed as if they were based on the radius, so the listed parallax for 4.22 ly would be 773.5 milliarcseconds, even though the measurement made over the diameter would be twice as large.)

[swansont]

!

Moderator Note

I will make official the request to know where you copied the work from. 

 

[John Cuthber]

Strangely, he did so, here.

 

[reerer]

On ‎10‎/‎29‎/‎2017 at 4:35 AM, swansont said:

!

Moderator Note

I will make official the request to know where you copied the work from. 

 

Everything that I post, the author is me.

 

 

To measure the distance of a 4.22 ly star using the earth's orbital diameter as the parallax reference distance requires a telescopic resolution of .00126 arcsec which is 79 times more powerful than the Hubble (.1 arcsec). The Hipparcos telescope is used to justify the measurement of the distance to a 4.22 light year star since the Hipparcos is described with a resolution of .001 arcsec but the Hubble's mirror diameter is 7.9 feet which is eight times larger than the Hipparacos mirror diameter (11 inches) yet the Hipparcos is 100 times more powerful than the Hubble which is not physically possible. I predict that the maximum resolution of an optical reflection telescope is .1 arcsec since the Webb has the resolution of .1 arcsec and has a mirror diameter of 21 feet. The most powerful telescope known to man is the Hubble. The maximum distance to a star calculated using the Hubble is,

 

 

A/θ = B = (1.4 x 10¹⁰ m) (3600) / (.1 arcsec) = .5.04 x 10¹⁴m = .05327 light years....................115

 

 

The propagation of the Sun through the stellar universe is used to increase the value of the parallax reference distance A to form a Hubble resolution of .001 arcsec but parallax is based on the stars of the stellar universe that are stationary which also includes the Sun which proves the Hubble's resolution is .1 arcsec. Even with a resolution of .001 arcsecs the maximum distance to determine the distance to any of the stars of the celestial universe would be limited to 4.22 ly; consequently, if the distance to a 4.22 ly star cannot be determine than the distance to a star more than 350 light years from the earth also cannot be measured no matter what method is used. A dimming method is used to determine the distance to the 7,000 ly Eagle Nebula but the Hubble proves the intensity of a star does not vary.

 

_____________________________________________________________________________________________________________________________________________________________________________________________________________________

 

The photographic images of the Eagle Nebula obtained using the Spitzer UV space telescope were created using computer induced images since to determine the distance to the 7,000 ly Eagle Nebula using the earth orbital diameter A and the distance to a 7,000 ly Eagle Nebula B would require a resolution of A/B = (1.4 x 10¹⁰ m) / (6.6 x 10¹⁹ m) = 2.12 x 10^-10 degrees or 7.62 x 10^-7 arcsec. Yet the Hubble has a resolution of .1 arcsec and the Spitzer has a resolution of 1 arcsec; consequently, astronomers cannot determine the distance to the 7,000 ly Eagle Nebula. A dimming method is used to determine the distance to the 7,000 ly Eagle Nebula but the Hubble proves the intensity of a star does not vary. If my derivation are incorrect that I wrote, I admit that I am wrong which is hope will help in the discussion.

 

 

 

 

 

 

[Strange]

19 minutes ago, reerer said:

To measure the distance of a 4.22 ly star using the earth's orbital diameter as the parallax reference distance requires a telescopic resolution of .00126 arcsec which is 79 times more powerful than the Hubble (.1 arcsec).

Repeating this when the multiple errors have been posted out more than once is just silly.

20 minutes ago, reerer said:

Everything that I post, the author is me.

Then how come you don't understand any of it?

21 minutes ago, reerer said:

If my derivation are incorrect that I wrote, I admit that I am wrong which is hope will help in the discussion.

You have never admitted you are wrong despite the fact that every one of your threads are just full of errors and nonsense.

[hypervalent_iodine]

!

Moderator Note

I think we're done here also.