Relativity and Astronomy?

What, if any, special relativity effect evidence themselves in
astronomical data? For instance, according to the HyperPhysics site
Super Novae are in theory visible out to 8 billion light years. And
according to Hubell's law Super Novae light sources at that distance
will have a velocity relative to an earth observer of 0.6c. This
corresponds to a relativistic time dilation factor of 1.25, so the
tail of super novae luminosity curves should be on average stretched
out by 25% for the farthest observable super novae. What kind of data
of this type is available?

Also, is doppler shifting due to the difference in velocities of
approaching and receding arms of galaxies detectable at 8 billion
light years and greater?

Pat

In article ,
(Pat Dolan) writes:

What, if any, special relativity effect evidence themselves in
astronomical data? For instance, according to the HyperPhysics site
Super Novae are in theory visible out to 8 billion light years.

When the distances are this large, you need to specify which of the many
distances you mean.

And
according to Hubell's law Super Novae light sources at that distance
will have a velocity relative to an earth observer of 0.6c. This
corresponds to a relativistic time dilation factor of 1.25, so the
tail of super novae luminosity curves should be on average stretched
out by 25% for the farthest observable super novae. What kind of data
of this type is available?

When distances are this large, forget about using special relativity to
do anything related to the "Hubble velocity". One has to use general
relativity.

The time dilation factor is simply 1+z, where z is the redshift. This
is valid in all cosmological models based on GR, even though the actual
velocity at that distance (again, both terms have to be defined) can
vary depending on the parameters of the model.

Also, is doppler shifting due to the difference in velocities of
approaching and receding arms of galaxies detectable at 8 billion
light years and greater?

This, on the other hand, is a "conventional velocity". It is detectable
as long as one can get separate spectra of both sides of the galaxy, or
measure the broadening of the spectral line due to rotation. Some
observer can probably say what the redshift record is here.

In article ,
(Pat Dolan) writes:

What, if any, special relativity effect evidence themselves in
astronomical data? For instance, according to the HyperPhysics site
Super Novae are in theory visible out to 8 billion light years.

When the distances are this large, you need to specify which of the many
distances you mean.

And
according to Hubell's law Super Novae light sources at that distance
will have a velocity relative to an earth observer of 0.6c. This
corresponds to a relativistic time dilation factor of 1.25, so the
tail of super novae luminosity curves should be on average stretched
out by 25% for the farthest observable super novae. What kind of data
of this type is available?

When distances are this large, forget about using special relativity to
do anything related to the "Hubble velocity". One has to use general
relativity.

The time dilation factor is simply 1+z, where z is the redshift. This
is valid in all cosmological models based on GR, even though the actual
velocity at that distance (again, both terms have to be defined) can
vary depending on the parameters of the model.

Also, is doppler shifting due to the difference in velocities of
approaching and receding arms of galaxies detectable at 8 billion
light years and greater?

This, on the other hand, is a "conventional velocity". It is detectable
as long as one can get separate spectra of both sides of the galaxy, or
measure the broadening of the spectral line due to rotation. Some
observer can probably say what the redshift record is here.

Phillip Helbig---remove CLOTHES to reply
wrote:
In article ,
(Pat Dolan) writes:

[...]
according to Hubell's law Super Novae light sources at that distance
will have a velocity relative to an earth observer of 0.6c. This
corresponds to a relativistic time dilation factor of 1.25, so the
tail of super novae luminosity curves should be on average stretched
out by 25% for the farthest observable super novae. What kind of data
of this type is available?

When distances are this large, forget about using special relativity to
do anything related to the "Hubble velocity". One has to use general
relativity.

The time dilation factor is simply 1+z, where z is the redshift. This
is valid in all cosmological models based on GR, even though the actual
velocity at that distance (again, both terms have to be defined) can
vary depending on the parameters of the model.

Let me add that this time dilation of supernova light curves is,
in fact, observed: see Goldhaber et al., Astrophys. J. 558 (2001) 359,
available on the Web at http://arxiv.org/abs/astro-ph/0104382 .

Steve Carlip

Phillip Helbig---remove CLOTHES to reply
wrote:
In article ,
(Pat Dolan) writes:

[...]
according to Hubell's law Super Novae light sources at that distance
will have a velocity relative to an earth observer of 0.6c. This
corresponds to a relativistic time dilation factor of 1.25, so the
tail of super novae luminosity curves should be on average stretched
out by 25% for the farthest observable super novae. What kind of data
of this type is available?

When distances are this large, forget about using special relativity to
do anything related to the "Hubble velocity". One has to use general
relativity.

The time dilation factor is simply 1+z, where z is the redshift. This
is valid in all cosmological models based on GR, even though the actual
velocity at that distance (again, both terms have to be defined) can
vary depending on the parameters of the model.

Let me add that this time dilation of supernova light curves is,
in fact, observed: see Goldhaber et al., Astrophys. J. 558 (2001) 359,
available on the Web at http://arxiv.org/abs/astro-ph/0104382 .

Steve Carlip

"PD" == Pat Dolan writes:

PD What, if any, special relativity effect evidence themselves in
PD astronomical data? For instance, according to the HyperPhysics
PD site Super Novae are in theory visible out to 8 billion light
PD years.

As Philip Herbig and Steve Carlip have pointed out, this is a general
relativistic effect. If you are interested in special relativistic
effects, my nominations would be synchrotron radiation and
superluminal motion.

Synchrotron radiation results from relativistic electrons moving in a
magnetic field. It is generally accepted to be the emission mechanism
for many radio sources.

Superluminal motion is effectively an optical illusion resulting from
relativistic material traveling toward the observer, e.g.,
URL:http://www.astr.ua.edu/keel/agn/3c279.html.

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"PD" == Pat Dolan writes:

PD What, if any, special relativity effect evidence themselves in
PD astronomical data? For instance, according to the HyperPhysics
PD site Super Novae are in theory visible out to 8 billion light
PD years.

As Philip Herbig and Steve Carlip have pointed out, this is a general
relativistic effect. If you are interested in special relativistic
effects, my nominations would be synchrotron radiation and
superluminal motion.

Synchrotron radiation results from relativistic electrons moving in a
magnetic field. It is generally accepted to be the emission mechanism
for many radio sources.

Superluminal motion is effectively an optical illusion resulting from
relativistic material traveling toward the observer, e.g.,
URL:http://www.astr.ua.edu/keel/agn/3c279.html.

--
Lt. Lazio, HTML police | e-mail:
No means no, stop rape. | http://patriot.net/%7Ejlazio/
sci.astro FAQ at http://sciastro.astronomy.net/sci.astro.html