Double stars I discovered!

On May 28, 10:50 pm, wrote:
On May 28, 1:31 pm, "Mike Dworetsky"



wrote:

Thank you, those links are pretty useful!
In an earlier post on this thread I said I discovered a 10.5-11-ish
magnitude companion to the 8th magnitude red star BD+16 3495 in
Hercules:http://www.freewebs.com/aa_spaceagen...63495_ahad.jpg

If we now compare the POSS I image of this star goin back to 1950s:http://tinyurl.com/pbh5xqagainstthe POSS II image plate in the
1990s:http://tinyurl.com/pklvqp
We note that the secondary companion has shifted closer toward the
primary by a significant margin (1950's vs 1990s)!! Could this be due
to orbital motion? Or is it a high proper motion foreground star that
is simply passing BD+16 3495 due to our line of sight?!

---------------------------------------------------------------------------*------------

Well spotted. Probably the latter, given that it has moved wrt the brighter
star and the other 3 faint background objects. That would be an incredible
amount of orbital motion for only 30-40 years, for such a large separation.
Possibly it is a high proper motion background star, given its faintness.
Could be a halo star (which often have very high pm and RV compared to disk
population)? +16 3495 has a relatively small proper motion as previously
noted. If it is a true M0 V as Simbad suggests with M0 D, then it must be
only a few parsecs away.

--
Mike Dworetsky

(Remove pants sp*mbl*ck to reply)- Hide quoted text -

- Show quoted text -

Sounds plausible.
We cannot rule out binarity entirely, however.
Consider the binary star 61 Cygni, consisting of a pair of red dwarfs,
somewhat similar to BD+16 3495 and just a few parsecs away from us.
Angular separation (rho) is ~30 arc-seconds and the orbital period (P)
is ~650 years. If we assume a circular orbit in the plane of the sky,
then the full orbit circumference would be 2 * Pi * 30 = 188 arc-
seconds.

In the 40 year interval between POSS I and POSS II surveys, we expect
the secondary star to travel (40/650 * 188 = ~ 12 arc-seconds.

This appears to be the sort of angular distance that the secondary
star in my BD+16 3495 pair has covered between 1950s and 1990s (POSS I
& II).

The other interesting thing to note is the match in red coloration of
both stars in the pair; red dwarf binaries seem to occur in relative
abundance for some reason in the Solar neighborhood, e.g. Groombridge
34 A/B, Kruger 60 A/B, 61 Cygni A/B, Struve 2398 A/B, etc.

Abdul Ahad

Hiya

Look, you can't make things be because you want them to be, you've got
to have some data.

Now, the red star that moves is in the Tycho catalogue and has a
proper motion logged for it. The brighter star, the BD star, also has
a proper motion in that catalogue.

Now, even if somehow this was one of the nearest stars to us and the
fact had been missed, what you say still cannot work, because even if
there was relative motion due orbital motion, both stars would have
very similar proper motions as they would also be moving through space
together if they were a gravitationally bound pair. For the fainter
star to be in orbit about the brighter star, both stars have to be in
motion together as well through space, one cannot leave the other
behind.

And the proper motions of the two stars are quite distinct.

The brighter star is classed as spectral type M0, shows no proper
motion to speak of, probably a moderately distant red giant. The
moved star appears to be somewhat red but not greatly so, might be a
foreground red dwarf (from the proper motion), might be a foreground K
dwarf, in fact a G dwarf isn't impossible either. That would lead to
a far bigger magnitude difference than actually exists for the pair.

But that last paragraph itself is speculative, based on unclear data.

What is clear is the object that is BD etc has moved little if any at
all since being photographed in 1898, whilst the other has moved about
13 arcseconds since being photographed in 1898.

In your 61 Cygni example, if you look into it, you will find that that
has not only had motion of one star about the other (actually 61 Cygni
is one of those fast enough and close enough that people can actually
calculate that both stars are moving around a barycentre and solve for
that, not one star around the other) but 61 Cygni has also has both
stars moving in space with proper motion.

You cannot make two stars be binaries without a fair amount of
evidence, and even then only the ones with orbital solutions are very
safe. Common proper motion pairs exist too, which of these are
binaries and which are common proper motion and which are just joint
members of moving streams, all are overlap and borderline type areas.

On May 29, 9:39*pm, wrote:
On May 28, 10:50 pm, wrote:





On May 28, 1:31 pm, "Mike Dworetsky"

wrote:

Thank you, those links are pretty useful!
In an earlier post on this thread I said I discovered a 10.5-11-ish
magnitude companion to the 8th magnitude red star BD+16 3495 in
Hercules:http://www.freewebs.com/aa_spaceagen...63495_ahad.jpg

If we now compare the POSS I image of this star goin back to 1950s:http://tinyurl.com/pbh5xqagainstthePOSS II image plate in the
1990s:http://tinyurl.com/pklvqp
We note that the secondary companion has shifted closer toward the
primary by a significant margin (1950's vs 1990s)!! Could this be due
to orbital motion? Or is it a high proper motion foreground star that
is simply passing BD+16 3495 due to our line of sight?!

---------------------------------------------------------------------------**------------

Well spotted. *Probably the latter, given that it has moved wrt the brighter
star and the other 3 faint background objects. *That would be an incredible
amount of orbital motion for only 30-40 years, for such a large separation.
Possibly it is a high proper motion background star, given its faintness.
Could be a halo star (which often have very high pm and RV compared to disk
population)? *+16 3495 has a relatively small proper motion as previously
noted. *If it is a true M0 V as Simbad suggests with M0 D, then it must be
only a few parsecs away.

--
Mike Dworetsky

(Remove pants sp*mbl*ck to reply)- Hide quoted text -

- Show quoted text -

Sounds plausible.
We cannot rule out binarity entirely, however.
Consider the binary star 61 Cygni, consisting of a pair of red dwarfs,
somewhat similar to BD+16 3495 and just a few parsecs away from us.
Angular separation (rho) is ~30 arc-seconds and the orbital period (P)
is ~650 years. If we assume a circular orbit in the plane of the sky,
then the full orbit circumference would be 2 * Pi * 30 = 188 arc-
seconds.

In the 40 year interval between POSS I and POSS II surveys, we expect
the secondary star to travel (40/650 * 188 = ~ 12 arc-seconds.

This appears to be the sort of angular distance that the secondary
star in my BD+16 3495 pair has covered between 1950s and 1990s (POSS I
& II).

The other interesting thing to note is the match in red coloration of
both stars in the pair; red dwarf binaries seem to occur in relative
abundance for some reason in the Solar neighborhood, e.g. Groombridge
34 A/B, Kruger 60 A/B, 61 Cygni A/B, Struve 2398 A/B, etc.

Abdul Ahad

Hiya

Look, you can't make things be because you want them to be, you've got
to have some data.

Now, the red star that moves is in the Tycho catalogue and has a
proper motion logged for it. *The brighter star, the BD star, also has
a proper motion in that catalogue.

Now, even if somehow this was one of the nearest stars to us and the
fact had been missed, what you say still cannot work, because even if
there was relative motion due orbital motion, both stars would have
very similar proper motions as they would also be moving through space
together if they were a gravitationally bound pair. *For the fainter
star to be in orbit about the brighter star, both stars have to be in
motion together as well through space, one cannot leave the other
behind.

And the proper motions of the two stars are quite distinct.

The brighter star is classed as spectral type M0, shows no proper
motion to speak of, probably a moderately distant red giant. *The
moved star appears to be somewhat red but not greatly so, might be a
foreground red dwarf (from the proper motion), might be a foreground K
dwarf, in fact a G dwarf isn't impossible either. *That would lead to
a far bigger magnitude difference than actually exists for the pair.

But that last paragraph itself is speculative, based on unclear data.

What is clear is the object that is BD etc has moved little if any at
all since being photographed in 1898, whilst the other has moved about
13 arcseconds since being photographed in 1898.

In your 61 Cygni example, if you look into it, you will find that that
has not only had motion of one star about the other (actually 61 Cygni
is one of those fast enough and close enough that people can actually
calculate that both stars are moving around a barycentre and solve for
that, not one star around the other) but 61 Cygni has also has both
stars moving in space with proper motion.

You cannot make two stars be binaries without a fair amount of
evidence, and even then only the ones with orbital solutions are very
safe. *Common proper motion pairs exist too, which of these are
binaries and which are common proper motion and which are just joint
members of moving streams, all are overlap and borderline type areas.- Hide quoted text -

- Show quoted text -

You're right. We do need more data to confirm or deny if this is a
genuine binary pair or simply a foreground vs background stellar
alignment. The specific data we need is *parallax*. For both stars.
Does Tycho catalog list this?


As for the lack of moton of primary across the sky, suppose if all the
motion of this star was directed along its radial velocity line? So
that it appears stationary in the sky, with no tangential component to
its PM? In that case, we would have exactly the kind of scenario which
we are seeing, where we see the primary stationary in the middle, with
the secondary moving about it much like in this diagram:

http://www.dibonsmith.com/cyg_del.gif

On May 29, 11:54*pm, wrote:
On May 29, 9:39*pm, wrote:





On May 28, 10:50 pm, wrote:

On May 28, 1:31 pm, "Mike Dworetsky"

wrote:

Thank you, those links are pretty useful!
In an earlier post on this thread I said I discovered a 10.5-11-ish
magnitude companion to the 8th magnitude red star BD+16 3495 in
Hercules:http://www.freewebs.com/aa_spaceagen...63495_ahad.jpg

If we now compare the POSS I image of this star goin back to 1950s:http://tinyurl.com/pbh5xqagainstthePOSSII image plate in the
1990s:http://tinyurl.com/pklvqp
We note that the secondary companion has shifted closer toward the
primary by a significant margin (1950's vs 1990s)!! Could this be due
to orbital motion? Or is it a high proper motion foreground star that
is simply passing BD+16 3495 due to our line of sight?!

---------------------------------------------------------------------------***------------

Well spotted. *Probably the latter, given that it has moved wrt the brighter
star and the other 3 faint background objects. *That would be an incredible
amount of orbital motion for only 30-40 years, for such a large separation.
Possibly it is a high proper motion background star, given its faintness.
Could be a halo star (which often have very high pm and RV compared to disk
population)? *+16 3495 has a relatively small proper motion as previously
noted. *If it is a true M0 V as Simbad suggests with M0 D, then it must be
only a few parsecs away.

--
Mike Dworetsky

(Remove pants sp*mbl*ck to reply)- Hide quoted text -

- Show quoted text -

Sounds plausible.
We cannot rule out binarity entirely, however.
Consider the binary star 61 Cygni, consisting of a pair of red dwarfs,
somewhat similar to BD+16 3495 and just a few parsecs away from us.
Angular separation (rho) is ~30 arc-seconds and the orbital period (P)
is ~650 years. If we assume a circular orbit in the plane of the sky,
then the full orbit circumference would be 2 * Pi * 30 = 188 arc-
seconds.

In the 40 year interval between POSS I and POSS II surveys, we expect
the secondary star to travel (40/650 * 188 = ~ 12 arc-seconds.

This appears to be the sort of angular distance that the secondary
star in my BD+16 3495 pair has covered between 1950s and 1990s (POSS I
& II).

The other interesting thing to note is the match in red coloration of
both stars in the pair; red dwarf binaries seem to occur in relative
abundance for some reason in the Solar neighborhood, e.g. Groombridge
34 A/B, Kruger 60 A/B, 61 Cygni A/B, Struve 2398 A/B, etc.

Abdul Ahad

Hiya

Look, you can't make things be because you want them to be, you've got
to have some data.

Now, the red star that moves is in the Tycho catalogue and has a
proper motion logged for it. *The brighter star, the BD star, also has
a proper motion in that catalogue.

Now, even if somehow this was one of the nearest stars to us and the
fact had been missed, what you say still cannot work, because even if
there was relative motion due orbital motion, both stars would have
very similar proper motions as they would also be moving through space
together if they were a gravitationally bound pair. *For the fainter
star to be in orbit about the brighter star, both stars have to be in
motion together as well through space, one cannot leave the other
behind.

And the proper motions of the two stars are quite distinct.

The brighter star is classed as spectral type M0, shows no proper
motion to speak of, probably a moderately distant red giant. *The
moved star appears to be somewhat red but not greatly so, might be a
foreground red dwarf (from the proper motion), might be a foreground K
dwarf, in fact a G dwarf isn't impossible either. *That would lead to
a far bigger magnitude difference than actually exists for the pair.

But that last paragraph itself is speculative, based on unclear data.

What is clear is the object that is BD etc has moved little if any at
all since being photographed in 1898, whilst the other has moved about
13 arcseconds since being photographed in 1898.

In your 61 Cygni example, if you look into it, you will find that that
has not only had motion of one star about the other (actually 61 Cygni
is one of those fast enough and close enough that people can actually
calculate that both stars are moving around a barycentre and solve for
that, not one star around the other) but 61 Cygni has also has both
stars moving in space with proper motion.

You cannot make two stars be binaries without a fair amount of
evidence, and even then only the ones with orbital solutions are very
safe. *Common proper motion pairs exist too, which of these are
binaries and which are common proper motion and which are just joint
members of moving streams, all are overlap and borderline type areas.- Hide quoted text -

- Show quoted text -

You're right. We do need more data to confirm or deny if this is a
genuine binary pair or simply a foreground vs background stellar
alignment. The specific data we need is *parallax*. For both stars.
Does Tycho catalog list this?

As for the lack of moton of primary across the sky, suppose if all the
motion of this star was directed along its radial velocity line? So
that it appears stationary in the sky, with no tangential component to
its PM? In that case, we would have exactly the kind of scenario which
we are seeing, where we see the primary stationary in the middle, with
the secondary moving about it much like in this diagram:

http://www.dibonsmith.com/cyg_del.gif- Hide quoted text -

- Show quoted text -

The other point you mentioned is the secondary has moved about 13
arcseconds since being photographed in 1898. So if we have photographs
taken in 1898, 1950s and 1990s (the last two in the POSS surveys)..can
we duduce if the motion has been in a straight line or a curve? If the
movements are non-linear, then that would be indicative of orbital
motion. If the motion is a perfect straight line, then this would rule
out elliptical orbital motion.

On May 29, 9:39*pm, wrote:
On May 28, 10:50 pm, wrote:





On May 28, 1:31 pm, "Mike Dworetsky"

wrote:

Thank you, those links are pretty useful!
In an earlier post on this thread I said I discovered a 10.5-11-ish
magnitude companion to the 8th magnitude red star BD+16 3495 in
Hercules:http://www.freewebs.com/aa_spaceagen...63495_ahad.jpg

If we now compare the POSS I image of this star goin back to 1950s:http://tinyurl.com/pbh5xqagainstthePOSS II image plate in the
1990s:http://tinyurl.com/pklvqp
We note that the secondary companion has shifted closer toward the
primary by a significant margin (1950's vs 1990s)!! Could this be due
to orbital motion? Or is it a high proper motion foreground star that
is simply passing BD+16 3495 due to our line of sight?!

---------------------------------------------------------------------------**------------

Well spotted. *Probably the latter, given that it has moved wrt the brighter
star and the other 3 faint background objects. *That would be an incredible
amount of orbital motion for only 30-40 years, for such a large separation.
Possibly it is a high proper motion background star, given its faintness.
Could be a halo star (which often have very high pm and RV compared to disk
population)? *+16 3495 has a relatively small proper motion as previously
noted. *If it is a true M0 V as Simbad suggests with M0 D, then it must be
only a few parsecs away.

--
Mike Dworetsky

(Remove pants sp*mbl*ck to reply)- Hide quoted text -

- Show quoted text -

Sounds plausible.
We cannot rule out binarity entirely, however.
Consider the binary star 61 Cygni, consisting of a pair of red dwarfs,
somewhat similar to BD+16 3495 and just a few parsecs away from us.
Angular separation (rho) is ~30 arc-seconds and the orbital period (P)
is ~650 years. If we assume a circular orbit in the plane of the sky,
then the full orbit circumference would be 2 * Pi * 30 = 188 arc-
seconds.

In the 40 year interval between POSS I and POSS II surveys, we expect
the secondary star to travel (40/650 * 188 = ~ 12 arc-seconds.

This appears to be the sort of angular distance that the secondary
star in my BD+16 3495 pair has covered between 1950s and 1990s (POSS I
& II).

The other interesting thing to note is the match in red coloration of
both stars in the pair; red dwarf binaries seem to occur in relative
abundance for some reason in the Solar neighborhood, e.g. Groombridge
34 A/B, Kruger 60 A/B, 61 Cygni A/B, Struve 2398 A/B, etc.

Abdul Ahad

Hiya

Look, you can't make things be because you want them to be, you've got
to have some data.

Now, the red star that moves is in the Tycho catalogue and has a
proper motion logged for it. *The brighter star, the BD star, also has
a proper motion in that catalogue.

Now, even if somehow this was one of the nearest stars to us and the
fact had been missed, what you say still cannot work, because even if
there was relative motion due orbital motion, both stars would have
very similar proper motions as they would also be moving through space
together if they were a gravitationally bound pair. *For the fainter
star to be in orbit about the brighter star, both stars have to be in
motion together as well through space, one cannot leave the other
behind.

And the proper motions of the two stars are quite distinct.

The brighter star is classed as spectral type M0, shows no proper
motion to speak of, probably a moderately distant red giant. *The
moved star appears to be somewhat red but not greatly so, might be a
foreground red dwarf (from the proper motion), might be a foreground K
dwarf, in fact a G dwarf isn't impossible either. *That would lead to
a far bigger magnitude difference than actually exists for the pair.

But that last paragraph itself is speculative, based on unclear data.

What is clear is the object that is BD etc has moved little if any at
all since being photographed in 1898, whilst the other has moved about
13 arcseconds since being photographed in 1898.

In your 61 Cygni example, if you look into it, you will find that that
has not only had motion of one star about the other (actually 61 Cygni
is one of those fast enough and close enough that people can actually
calculate that both stars are moving around a barycentre and solve for
that, not one star around the other) but 61 Cygni has also has both
stars moving in space with proper motion.

You cannot make two stars be binaries without a fair amount of
evidence, and even then only the ones with orbital solutions are very
safe. *Common proper motion pairs exist too, which of these are
binaries and which are common proper motion and which are just joint
members of moving streams, all are overlap and borderline type areas.- Hide quoted text -

- Show quoted text -

The other point you mentioned is the secondary has moved about 13
arcseconds since being photographed in 1898. So if we have
photographs
taken in 1898, 1950s and 1990s (the last two in the POSS
surveys)..can
we duduce if the motion has been in a straight line or a curve? If
the
movements are non-linear, then that would be indicative of orbital
motion. If the motion is a perfect straight line, then this would
rule
out elliptical orbital motion.

You're right. We do need more data to confirm or deny if this is a
genuine binary pair or simply a foreground vs background stellar
alignment. The specific data we need is *parallax*. For both stars.
Does Tycho catalog list this?

Not in general. While Hipparcos stars (which have a measured parallax
and parallax error) that are just in the Tycho catalog obviously have
parallaxes, the Tycho stars don't have measured parallaxes.

wrote in message
...
On May 29, 9:39 pm, wrote:
On May 28, 10:50 pm, wrote:





On May 28, 1:31 pm, "Mike Dworetsky"

wrote:

Thank you, those links are pretty useful!
In an earlier post on this thread I said I discovered a 10.5-11-ish
magnitude companion to the 8th magnitude red star BD+16 3495 in
Hercules:http://www.freewebs.com/aa_spaceagen...63495_ahad.jpg

If we now compare the POSS I image of this star goin back to
1950s:http://tinyurl.com/pbh5xqagainstthePOSS II image plate in the
1990s:http://tinyurl.com/pklvqp
We note that the secondary companion has shifted closer toward the
primary by a significant margin (1950's vs 1990s)!! Could this be due
to orbital motion? Or is it a high proper motion foreground star that
is simply passing BD+16 3495 due to our line of sight?!

---------------------------------------------------------------------------**------------

Well spotted. Probably the latter, given that it has moved wrt the
brighter
star and the other 3 faint background objects. That would be an
incredible
amount of orbital motion for only 30-40 years, for such a large
separation.
Possibly it is a high proper motion background star, given its
faintness.
Could be a halo star (which often have very high pm and RV compared to
disk
population)? +16 3495 has a relatively small proper motion as
previously
noted. If it is a true M0 V as Simbad suggests with M0 D, then it must
be
only a few parsecs away.

--
Mike Dworetsky

(Remove pants sp*mbl*ck to reply)- Hide quoted text -

- Show quoted text -

Sounds plausible.
We cannot rule out binarity entirely, however.
Consider the binary star 61 Cygni, consisting of a pair of red dwarfs,
somewhat similar to BD+16 3495 and just a few parsecs away from us.
Angular separation (rho) is ~30 arc-seconds and the orbital period (P)
is ~650 years. If we assume a circular orbit in the plane of the sky,
then the full orbit circumference would be 2 * Pi * 30 = 188 arc-
seconds.

In the 40 year interval between POSS I and POSS II surveys, we expect
the secondary star to travel (40/650 * 188 = ~ 12 arc-seconds.

This appears to be the sort of angular distance that the secondary
star in my BD+16 3495 pair has covered between 1950s and 1990s (POSS I
& II).

The other interesting thing to note is the match in red coloration of
both stars in the pair; red dwarf binaries seem to occur in relative
abundance for some reason in the Solar neighborhood, e.g. Groombridge
34 A/B, Kruger 60 A/B, 61 Cygni A/B, Struve 2398 A/B, etc.

Abdul Ahad

Hiya

Look, you can't make things be because you want them to be, you've got
to have some data.

Now, the red star that moves is in the Tycho catalogue and has a
proper motion logged for it. The brighter star, the BD star, also has
a proper motion in that catalogue.

Now, even if somehow this was one of the nearest stars to us and the
fact had been missed, what you say still cannot work, because even if
there was relative motion due orbital motion, both stars would have
very similar proper motions as they would also be moving through space
together if they were a gravitationally bound pair. For the fainter
star to be in orbit about the brighter star, both stars have to be in
motion together as well through space, one cannot leave the other
behind.

And the proper motions of the two stars are quite distinct.

The brighter star is classed as spectral type M0, shows no proper
motion to speak of, probably a moderately distant red giant. The
moved star appears to be somewhat red but not greatly so, might be a
foreground red dwarf (from the proper motion), might be a foreground K
dwarf, in fact a G dwarf isn't impossible either. That would lead to
a far bigger magnitude difference than actually exists for the pair.

But that last paragraph itself is speculative, based on unclear data.

What is clear is the object that is BD etc has moved little if any at
all since being photographed in 1898, whilst the other has moved about
13 arcseconds since being photographed in 1898.

In your 61 Cygni example, if you look into it, you will find that that
has not only had motion of one star about the other (actually 61 Cygni
is one of those fast enough and close enough that people can actually
calculate that both stars are moving around a barycentre and solve for
that, not one star around the other) but 61 Cygni has also has both
stars moving in space with proper motion.

You cannot make two stars be binaries without a fair amount of
evidence, and even then only the ones with orbital solutions are very
safe. Common proper motion pairs exist too, which of these are
binaries and which are common proper motion and which are just joint
members of moving streams, all are overlap and borderline type areas.-
Hide quoted text -

- Show quoted text -

You're right. We do need more data to confirm or deny if this is a
genuine binary pair or simply a foreground vs background stellar
alignment. The specific data we need is *parallax*. For both stars.
Does Tycho catalog list this?


As for the lack of moton of primary across the sky, suppose if all the
motion of this star was directed along its radial velocity line? So
that it appears stationary in the sky, with no tangential component to
its PM? In that case, we would have exactly the kind of scenario which
we are seeing, where we see the primary stationary in the middle, with
the secondary moving about it much like in this diagram:

http://www.dibonsmith.com/cyg_del.gif

--------------------------------------------------------------------------------------

The point being made is that a claim of a *possible* wide binary is all very
well, but without solid proof of a physical connection (either via proximity
statistics, such as Aitken's criterion, or by measured common proper motion,
radial velocity and parallax), it is better to hold such a claim in abeyance
until that evidence exists.

The catalogues of variable stars are full of suspected variables that turned
out to be dubious observations rather than genuine discoveries. So it is
better for the science to be conservative about such things, otherwise we
would all spend too much time investigating phantoms.

None of this should stop you from pursuing your own investigations, but
trying to get them into a big catalogue (Washington Double Star Cat) wastes
the time of everyone else. Some day there will be another better
positional/proper motion satellite (a sort of Hipparcos II), or an improved
hybrid of ground-based/space-based data frames, which may resolve these
matters. Until then, we just have to be patient.

For example, while what you suggest is physically possible (a nearby star
happens to be aimed straight at us or away from us) but unlikely. And the
rate of motion of the secondary of your "binary" is so high as to make it
unlikely that the two are connected.

No, Tycho Catalogue does not list parallax unless the star was also in the
Hipparcos Catalogue, though I believe it lists proper motion (derived from
the Astrographic Catalogue, etc in many cases). Tycho was primarily a
photometry exercise for fainter stars.

--
Mike Dworetsky

(Remove pants sp*mbl*ck to reply)

wrote in message
...
On May 29, 9:39 pm, wrote:
On May 28, 10:50 pm, wrote:





On May 28, 1:31 pm, "Mike Dworetsky"

wrote:

Thank you, those links are pretty useful!
In an earlier post on this thread I said I discovered a 10.5-11-ish
magnitude companion to the 8th magnitude red star BD+16 3495 in
Hercules:http://www.freewebs.com/aa_spaceagen...63495_ahad.jpg

If we now compare the POSS I image of this star goin back to
1950s:http://tinyurl.com/pbh5xqagainstthePOSS II image plate in the
1990s:http://tinyurl.com/pklvqp
We note that the secondary companion has shifted closer toward the
primary by a significant margin (1950's vs 1990s)!! Could this be due
to orbital motion? Or is it a high proper motion foreground star that
is simply passing BD+16 3495 due to our line of sight?!

---------------------------------------------------------------------------**------------

Well spotted. Probably the latter, given that it has moved wrt the
brighter
star and the other 3 faint background objects. That would be an
incredible
amount of orbital motion for only 30-40 years, for such a large
separation.
Possibly it is a high proper motion background star, given its
faintness.
Could be a halo star (which often have very high pm and RV compared to
disk
population)? +16 3495 has a relatively small proper motion as
previously
noted. If it is a true M0 V as Simbad suggests with M0 D, then it must
be
only a few parsecs away.

--
Mike Dworetsky

(Remove pants sp*mbl*ck to reply)- Hide quoted text -

- Show quoted text -

Sounds plausible.
We cannot rule out binarity entirely, however.
Consider the binary star 61 Cygni, consisting of a pair of red dwarfs,
somewhat similar to BD+16 3495 and just a few parsecs away from us.
Angular separation (rho) is ~30 arc-seconds and the orbital period (P)
is ~650 years. If we assume a circular orbit in the plane of the sky,
then the full orbit circumference would be 2 * Pi * 30 = 188 arc-
seconds.

In the 40 year interval between POSS I and POSS II surveys, we expect
the secondary star to travel (40/650 * 188 = ~ 12 arc-seconds.

This appears to be the sort of angular distance that the secondary
star in my BD+16 3495 pair has covered between 1950s and 1990s (POSS I
& II).

The other interesting thing to note is the match in red coloration of
both stars in the pair; red dwarf binaries seem to occur in relative
abundance for some reason in the Solar neighborhood, e.g. Groombridge
34 A/B, Kruger 60 A/B, 61 Cygni A/B, Struve 2398 A/B, etc.

Abdul Ahad

Hiya

Look, you can't make things be because you want them to be, you've got
to have some data.

Now, the red star that moves is in the Tycho catalogue and has a
proper motion logged for it. The brighter star, the BD star, also has
a proper motion in that catalogue.

Now, even if somehow this was one of the nearest stars to us and the
fact had been missed, what you say still cannot work, because even if
there was relative motion due orbital motion, both stars would have
very similar proper motions as they would also be moving through space
together if they were a gravitationally bound pair. For the fainter
star to be in orbit about the brighter star, both stars have to be in
motion together as well through space, one cannot leave the other
behind.

And the proper motions of the two stars are quite distinct.

The brighter star is classed as spectral type M0, shows no proper
motion to speak of, probably a moderately distant red giant. The
moved star appears to be somewhat red but not greatly so, might be a
foreground red dwarf (from the proper motion), might be a foreground K
dwarf, in fact a G dwarf isn't impossible either. That would lead to
a far bigger magnitude difference than actually exists for the pair.

But that last paragraph itself is speculative, based on unclear data.

What is clear is the object that is BD etc has moved little if any at
all since being photographed in 1898, whilst the other has moved about
13 arcseconds since being photographed in 1898.

In your 61 Cygni example, if you look into it, you will find that that
has not only had motion of one star about the other (actually 61 Cygni
is one of those fast enough and close enough that people can actually
calculate that both stars are moving around a barycentre and solve for
that, not one star around the other) but 61 Cygni has also has both
stars moving in space with proper motion.

You cannot make two stars be binaries without a fair amount of
evidence, and even then only the ones with orbital solutions are very
safe. Common proper motion pairs exist too, which of these are
binaries and which are common proper motion and which are just joint
members of moving streams, all are overlap and borderline type areas.-
Hide quoted text -

- Show quoted text -

The other point you mentioned is the secondary has moved about 13
arcseconds since being photographed in 1898. So if we have
photographs
taken in 1898, 1950s and 1990s (the last two in the POSS
surveys)..can
we duduce if the motion has been in a straight line or a curve? If
the
movements are non-linear, then that would be indicative of orbital
motion. If the motion is a perfect straight line, then this would
rule
out elliptical orbital motion.
-----------------------------------------------------------------------------------

The movement could be orbital along a straight line, but you would need to
see acceleration to call it orbital motion. At present there is
insufficient data on the rpoper motion (only three epochs?). My view
remains that this is very unlikely to be a true binary.

--
Mike Dworetsky

(Remove pants sp*mbl*ck to reply)

On May 29, 11:27 pm, wrote:
On May 29, 9:39 pm, wrote:



On May 28, 10:50 pm, wrote:

On May 28, 1:31 pm, "Mike Dworetsky"

wrote:

Thank you, those links are pretty useful!
In an earlier post on this thread I said I discovered a 10.5-11-ish
magnitude companion to the 8th magnitude red star BD+16 3495 in
Hercules:http://www.freewebs.com/aa_spaceagen...63495_ahad.jpg

If we now compare the POSS I image of this star goin back to 1950s:http://tinyurl.com/pbh5xqagainstthePOSSII image plate in the
1990s:http://tinyurl.com/pklvqp
We note that the secondary companion has shifted closer toward the
primary by a significant margin (1950's vs 1990s)!! Could this be due
to orbital motion? Or is it a high proper motion foreground star that
is simply passing BD+16 3495 due to our line of sight?!

---------------------------------------------------------------------------**------------

Well spotted. Probably the latter, given that it has moved wrt the brighter
star and the other 3 faint background objects. That would be an incredible
amount of orbital motion for only 30-40 years, for such a large separation.
Possibly it is a high proper motion background star, given its faintness.
Could be a halo star (which often have very high pm and RV compared to disk
population)? +16 3495 has a relatively small proper motion as previously
noted. If it is a true M0 V as Simbad suggests with M0 D, then it must be
only a few parsecs away.

--
Mike Dworetsky

(Remove pants sp*mbl*ck to reply)- Hide quoted text -

- Show quoted text -

Sounds plausible.
We cannot rule out binarity entirely, however.
Consider the binary star 61 Cygni, consisting of a pair of red dwarfs,
somewhat similar to BD+16 3495 and just a few parsecs away from us.
Angular separation (rho) is ~30 arc-seconds and the orbital period (P)
is ~650 years. If we assume a circular orbit in the plane of the sky,
then the full orbit circumference would be 2 * Pi * 30 = 188 arc-
seconds.

In the 40 year interval between POSS I and POSS II surveys, we expect
the secondary star to travel (40/650 * 188 = ~ 12 arc-seconds.

This appears to be the sort of angular distance that the secondary
star in my BD+16 3495 pair has covered between 1950s and 1990s (POSS I
& II).

The other interesting thing to note is the match in red coloration of
both stars in the pair; red dwarf binaries seem to occur in relative
abundance for some reason in the Solar neighborhood, e.g. Groombridge
34 A/B, Kruger 60 A/B, 61 Cygni A/B, Struve 2398 A/B, etc.

Abdul Ahad

Hiya

Look, you can't make things be because you want them to be, you've got
to have some data.

Now, the red star that moves is in the Tycho catalogue and has a
proper motion logged for it. The brighter star, the BD star, also has
a proper motion in that catalogue.

Now, even if somehow this was one of the nearest stars to us and the
fact had been missed, what you say still cannot work, because even if
there was relative motion due orbital motion, both stars would have
very similar proper motions as they would also be moving through space
together if they were a gravitationally bound pair. For the fainter
star to be in orbit about the brighter star, both stars have to be in
motion together as well through space, one cannot leave the other
behind.

And the proper motions of the two stars are quite distinct.

The brighter star is classed as spectral type M0, shows no proper
motion to speak of, probably a moderately distant red giant. The
moved star appears to be somewhat red but not greatly so, might be a
foreground red dwarf (from the proper motion), might be a foreground K
dwarf, in fact a G dwarf isn't impossible either. That would lead to
a far bigger magnitude difference than actually exists for the pair.

But that last paragraph itself is speculative, based on unclear data.

What is clear is the object that is BD etc has moved little if any at
all since being photographed in 1898, whilst the other has moved about
13 arcseconds since being photographed in 1898.

In your 61 Cygni example, if you look into it, you will find that that
has not only had motion of one star about the other (actually 61 Cygni
is one of those fast enough and close enough that people can actually
calculate that both stars are moving around a barycentre and solve for
that, not one star around the other) but 61 Cygni has also has both
stars moving in space with proper motion.

You cannot make two stars be binaries without a fair amount of
evidence, and even then only the ones with orbital solutions are very
safe. Common proper motion pairs exist too, which of these are
binaries and which are common proper motion and which are just joint
members of moving streams, all are overlap and borderline type areas.- Hide quoted text -

- Show quoted text -

The other point you mentioned is the secondary has moved about 13
arcseconds since being photographed in 1898. So if we have
photographs
taken in 1898, 1950s and 1990s (the last two in the POSS
surveys)..can
we duduce if the motion has been in a straight line or a curve? If
the
movements are non-linear, then that would be indicative of orbital
motion. If the motion is a perfect straight line, then this would
rule
out elliptical orbital motion.


The WDS double star people have recently started another catalogue
called the Catalogue of Rectilinear Elements or something. It uses
the principles you mention yourself. The motion is not likely to be a
perfect straight line, because measurements aren't perfect, but it
should be straight enough. Given four data points only, you might
decide it is linear, you might decide it is curved. When you have
very little data it is possible to see anything. But yes, with the
positions from several epochs you can manage this. Use VizieR. Use
the positions from the AC2000.2, that will give you 1898.55. POSS I
positions for 1950s, use 2MASS or CMC14 positions for 2000s. If you
can get a POSS II position too, that is fine. And was there a Tycho2
positon too? That gives 1991.25 mean epoch.

You may have to search on the web for Rectilinear Catalogue, most of
the USNO websites have migrated recently.

On May 30, 7:17 am, "Mike Dworetsky"
wrote:
wrote in message

...
On May 29, 9:39 pm, wrote:



On May 28, 10:50 pm, wrote:

On May 28, 1:31 pm, "Mike Dworetsky"

wrote:

Thank you, those links are pretty useful!
In an earlier post on this thread I said I discovered a 10.5-11-ish
magnitude companion to the 8th magnitude red star BD+16 3495 in
Hercules:http://www.freewebs.com/aa_spaceagen...63495_ahad.jpg

If we now compare the POSS I image of this star goin back to
1950s:http://tinyurl.com/pbh5xqagainstthePOSSII image plate in the
1990s:http://tinyurl.com/pklvqp
We note that the secondary companion has shifted closer toward the
primary by a significant margin (1950's vs 1990s)!! Could this be due
to orbital motion? Or is it a high proper motion foreground star that
is simply passing BD+16 3495 due to our line of sight?!

---------------------------------------------------------------------------**------------

Well spotted. Probably the latter, given that it has moved wrt the
brighter
star and the other 3 faint background objects. That would be an
incredible
amount of orbital motion for only 30-40 years, for such a large
separation.
Possibly it is a high proper motion background star, given its
faintness.
Could be a halo star (which often have very high pm and RV compared to
disk
population)? +16 3495 has a relatively small proper motion as
previously
noted. If it is a true M0 V as Simbad suggests with M0 D, then it must
be
only a few parsecs away.

--
Mike Dworetsky

(Remove pants sp*mbl*ck to reply)- Hide quoted text -

- Show quoted text -

Sounds plausible.
We cannot rule out binarity entirely, however.
Consider the binary star 61 Cygni, consisting of a pair of red dwarfs,
somewhat similar to BD+16 3495 and just a few parsecs away from us.
Angular separation (rho) is ~30 arc-seconds and the orbital period (P)
is ~650 years. If we assume a circular orbit in the plane of the sky,
then the full orbit circumference would be 2 * Pi * 30 = 188 arc-
seconds.

In the 40 year interval between POSS I and POSS II surveys, we expect
the secondary star to travel (40/650 * 188 = ~ 12 arc-seconds.

This appears to be the sort of angular distance that the secondary
star in my BD+16 3495 pair has covered between 1950s and 1990s (POSS I
& II).

The other interesting thing to note is the match in red coloration of
both stars in the pair; red dwarf binaries seem to occur in relative
abundance for some reason in the Solar neighborhood, e.g. Groombridge
34 A/B, Kruger 60 A/B, 61 Cygni A/B, Struve 2398 A/B, etc.

Abdul Ahad

Hiya

Look, you can't make things be because you want them to be, you've got
to have some data.

Now, the red star that moves is in the Tycho catalogue and has a
proper motion logged for it. The brighter star, the BD star, also has
a proper motion in that catalogue.

Now, even if somehow this was one of the nearest stars to us and the
fact had been missed, what you say still cannot work, because even if
there was relative motion due orbital motion, both stars would have
very similar proper motions as they would also be moving through space
together if they were a gravitationally bound pair. For the fainter
star to be in orbit about the brighter star, both stars have to be in
motion together as well through space, one cannot leave the other
behind.

And the proper motions of the two stars are quite distinct.

The brighter star is classed as spectral type M0, shows no proper
motion to speak of, probably a moderately distant red giant. The
moved star appears to be somewhat red but not greatly so, might be a
foreground red dwarf (from the proper motion), might be a foreground K
dwarf, in fact a G dwarf isn't impossible either. That would lead to
a far bigger magnitude difference than actually exists for the pair.

But that last paragraph itself is speculative, based on unclear data.

What is clear is the object that is BD etc has moved little if any at
all since being photographed in 1898, whilst the other has moved about
13 arcseconds since being photographed in 1898.

In your 61 Cygni example, if you look into it, you will find that that
has not only had motion of one star about the other (actually 61 Cygni
is one of those fast enough and close enough that people can actually
calculate that both stars are moving around a barycentre and solve for
that, not one star around the other) but 61 Cygni has also has both
stars moving in space with proper motion.

You cannot make two stars be binaries without a fair amount of
evidence, and even then only the ones with orbital solutions are very
safe. Common proper motion pairs exist too, which of these are
binaries and which are common proper motion and which are just joint
members of moving streams, all are overlap and borderline type areas.-
Hide quoted text -

- Show quoted text -

You're right. We do need more data to confirm or deny if this is a
genuine binary pair or simply a foreground vs background stellar
alignment. The specific data we need is *parallax*. For both stars.
Does Tycho catalog list this?

As for the lack of moton of primary across the sky, suppose if all the
motion of this star was directed along its radial velocity line? So
that it appears stationary in the sky, with no tangential component to
its PM? In that case, we would have exactly the kind of scenario which
we are seeing, where we see the primary stationary in the middle, with
the secondary moving about it much like in this diagram:

http://www.dibonsmith.com/cyg_del.gif

--------------------------------------------------------------------------------------

The point being made is that a claim of a *possible* wide binary is all very
well, but without solid proof of a physical connection (either via proximity
statistics, such as Aitken's criterion, or by measured common proper motion,
radial velocity and parallax), it is better to hold such a claim in abeyance
until that evidence exists.

The catalogues of variable stars are full of suspected variables that turned
out to be dubious observations rather than genuine discoveries. So it is
better for the science to be conservative about such things, otherwise we
would all spend too much time investigating phantoms.

None of this should stop you from pursuing your own investigations, but
trying to get them into a big catalogue (Washington Double Star Cat) wastes
the time of everyone else. Some day there will be another better
positional/proper motion satellite (a sort of Hipparcos II), or an improved
hybrid of ground-based/space-based data frames, which may resolve these
matters. Until then, we just have to be patient.

For example, while what you suggest is physically possible (a nearby star
happens to be aimed straight at us or away from us) but unlikely. And the
rate of motion of the secondary of your "binary" is so high as to make it
unlikely that the two are connected.

No, Tycho Catalogue does not list parallax unless the star was also in the
Hipparcos Catalogue, though I believe it lists proper motion (derived from
the Astrographic Catalogue, etc in many cases). Tycho was primarily a
photometry exercise for fainter stars.

--
Mike Dworetsky

(Remove pants sp*mbl*ck to reply)

Listen to what this guy has said about your binaries. Well stated,
clearly expressed, no personal inflection or rudeness either intended
or accidentally expressed.

Beware false experts, there are many. You can usually tell the
helpful people by the general tone of their statements and how much
meaningful information they point you towards is.

With the spread of the internet and access to much data there is a
flood of results and possibilities, some real, some simply mistaken,
some false, and some from charlatans, and the system can't keep up.
For you to have a chance of something concrete you have to use a
mindset that makes you as rigorous as possible with as much
information as possible. Just chasing after the same point and making
more and more special circumstances does not add information, it just
adds questions, and it is not a matter of who argues most, it is a
matter of the data.

There are various self advertisers and madmen out there who will
regularly tell everyone how great they are in numerous online
resources, and all their discoveries and findings. You usually find
that they rarely publish, and when they do it is either wrong or
indifferent or borrowed. I am relying on some of them to cause great
harm to some groups who will insist on not protecting themselves
properly from such people despite concrete evidence of specific
instances of strong misconduct being presented. In fact, I will laugh
when it happens.

If you are truly interested the first aspect is to apply some rules
and discipline to the matter. Listen to your own decisions and
statements and decide how you would feel if they were being made to
you by a salesman on your doorstep trying to convince you to part with
money.

This fellow here has given you sound advice, he's not dismissed you
out of hand, he's not been rude or superior just pointing at clever
things and saying he knows better in his infinite experience, he's
given you guidance. That's getting a bit rare nowadays, especially
with the self appointed greats living upon the internet.

Move on from these stars and look elsewhere. Proper motion catalogues
for objects with large proper motions, and reading the Webb Society
Double Star Section Circulars and the Journal of Double Star
Observations, both freely available online, and using the WDS website,
may help you target better.

Be thoughtful in your assessment, however, not all the papers in these
journals are valid. For instance you will see that ukastronomy has
published many "doubles" that readily directly contravene the rules he
applies to yourself in such a discouraging and dismissive manner.
Rules he was unaware of until he saw them used by others, and then
still screwed it up himself half the time, hence why I take offence to
the way he so arrogantly dismisses you.

That is another reason you should listen when someone does give you
good advice, and not try to find ways out by thinking too much and
special pleading. Helpful people are becoming exceedingly rare. Self
glorifying self important dilletantes are becoming the replacement.
Take advantage of the good whilst it still exists.

We cannot make this star into a binary for you. But pointers have
been given to you where instead you can use the energy you are using
to go and look for real binaries.

Interest is good, obsession and fixation can occur if you are not
careful. If things where too easy to find they would have already
been found.