# Thread: The Sun, in an Open Cluster

1. ## The Sun, in an Open Cluster

"Thomas" <TMA1@yahoo.ca> wrote in message news:<48drc.2849\$J02.1602@edtnps84>...

That would make a nice target for an extrasolar probe. We'd need to
figure on getting the probe capable of travelling up to around 50% of
c thought, otherwise the travel period would be *sooo* long.

Imagine a route that takes it to all three stars over a 10 year
period, add the 4.5 years it takes to get signals back. I think that
would be an amazing mission. not one for our lifetimes i guess...

Some astronomers speculate that A & B may have rocky planets in their
respective habitable zones, the calculations suggesting that the two
stars wouldn't seriously peturb orbits closer to the star.

As Star A is 1.1 times Sol's mass it's main sequence life time would
be just around 8 billion years and star B has around 12 billion, if
i'm following the mathematics right.

2. ## The Sun, in an Open Cluster

"> > My second goal when posting is to try not to embarrass myself when

Sam is the judge of whether he should apologize NOT YOU.

Apology accepted.

explanation of
your idea. It makes for unambiguous communication. Something I strive for
all
the time.

3. ## The Sun, in an Open Cluster

Brian Tung wrote:

You may already know this, but the Yale Bright Star Catalog lists both
proper motion and radial velocity, along with position (of course) and
parallax. It should be straightforward to get a cartesian vector from
that.

The initial position in spherical coordinates is

P0 = (ra, dec, s)

where s, the distance in parsecs, is 1 / parallax. The position after
time t is

P1 = (ra + pra, dec + pdec, s + v)

where (pra, pdec) is the displacement due to proper motion and v is the
displacement due to radial velocity. Convert P0 and P1 to rectangular
coordinates and subtract to get the velocity vector (the displacement in
rectangular coordinates over time t).

- Ernie http://mywebpages.comcast.net/erniew

4. ## The Sun, in an Open Cluster

Ernie Wright wrote:

Yes, but I was hoping not to have to do all that pesky work.

Brian Tung <brian@isi.edu>
The Astronomy Corner at http://astro.isi.edu/
My Own Personal FAQ (SAA) at http://astro.isi.edu/reference/faq.txt

5. ## The Sun, in an Open Cluster

"Jeremiah J. Burton" <jburton@nospamhewittenergygroup.com> wrote in message news:<a51605754cd16be8707815112e416939@news.terane ws.com>...

It is astronomically unlikely (sorry for the pun!) that ANY of our
neighboring stars are kith and kin of the Sun. In the 4.7 billion
years since the Sun's birth (current best estimate) the Sun has
motions, factor in the gravitational doe-si-does that each member of
the open cluster gives each of its neighbors as they are "born", add
billions of years of being pushed by supernovas, include a few Milky
Way / minor galaxy collisions, and consider the numerous huge gas
clouds the Sun has sauntered through. The Sun may be surrounded by
cousins, but its brothers and sisters are spread throughout the
Galaxy.

When considering the question of galactic motion, I recalled a ship in
the Pacific that lost a container of tennis shoes in a storm. The
rotation of the currents in the Pacific mimic the rotation of the
stars about the galactic core. Many of the shoes washed up along the
shores of the Pacific Northwest, where folks arranged swap meets to
match shoes (color, size, style, L & R).

Now consider the rotation of the Pacific over a century. Over a
millennium. Over a million years. Islands have come and gone. The
continents themselves have shifted. What is the chance a million
years hence of finding two of the lost shoes on the same beach? After
dozens of rotations the Pacific has done a pretty good job of
shuffling the deck. Likewise, the Galaxy has thoroughly randomized
the locations of the stars in the original open cluster of the Sun's
birth.

The European Southern Observatory (motto: "ESO. Astronomy made in
Europe") recently released a study that investigated galactic motion.
Here is the summary:

"A team of astronomers from Denmark, Switzerland and Sweden [2] has
achieved a major breakthrough in our understanding of the Milky Way,
the galaxy in which we live.

After more than 1,000 nights of observations spread over 15 years,
they have determined the spatial motions of more than 14,000
solar-like stars residing in the neighbourhood of the Sun.

For the first time, the changing dynamics of the Milky Way since its
birth can now be studied in detail and with a stellar sample
sufficiently large to allow a sound analysis. The astronomers find
that our home galaxy has led a much more turbulent and chaotic life
than previously assumed."

For a popular account, check out the CNN story at:
http://www.cnn.com/2004/TECH/space/04/06/crazy.sun/

The official press release, along with a WAY COOL animation
demonstrating galactic rotation, is at:
http://www.eso.org/outreach/press-re.../pr-08-04.html

neighbourhood: Ages, metallicities and kinematic properties of ~14,000
F and G dwarfs", by B. Nordström et al., is available in PDF format
here:
http://www.edpsciences.org/papers/aa...ses/aa0959.pdf

The research is scheduled to be published in the European research
journal Astronomy & Astrophysics:
http://www.edpsciences.org/aa

¤ Clear skies & a star to steer by! >Michael ¤

6. ## The Sun, in an Open Cluster

Thomas <TMA1@yahoo.ca> wrote:

Well, that's your opinion. Not mine however.

Jim
--
Find me at http://www.ursaminorbeta.co.uk
"Brace yourself, this might make your eyes water."

7. ## The Sun, in an Open Cluster

Starry-Nite wrote:

Cool!

The catalog based on the work described in this paper is also available

http://cdsweb.u-strasbg.fr/viz-bin/Cat?V/117

- Ernie http://mywebpages.comcast.net/erniew

8. ## The Sun, in an Open Cluster

Brian Tung wrote:

I was asked recently for a 3D model of the solar neighborhood, so I had
most of the code I needed already.

Comparing what I got today with the data Michael Foerster posted about,
I got pretty good directions from the Yale data, but the magnitudes were
off, by as much as a factor of 2, presumably because the parallaxes in
Yale aren't as reliable. Pretty sure Yale predates Hipparcos.

An interesting diversion, at least. UVW data is in fields 42-44 of the
Nordstrom catalog. The summary page is

http://cdsweb.u-strasbg.fr/viz-bin/Cat?V/117

- Ernie http://mywebpages.comcast.net/erniew

9. ## The Sun, in an Open Cluster

Serendipity... A few hours after my previous post I saw a new story in
the journal Science on recent solar origin research , based on work at
Arizona State by Jeff Hester.

You can find the original news release at:
http://www.asu.edu/asunews/research/...h_creation.htm

It seems that the interstellar cloud that gave birth to the Sun was
even more violent than expected. Using data from the Spitzer,
Chandra, and Hubble space telescopes (Save The Hubble!), the team
found that characteristics of the star forming nebula indicate that
among our Sun?s brother and sister stars were a few giant stars.
These giants first cooked the nebula with intense UV radiation, and
then further shook up the neighborhood with supernova explosions.

"People have long imagined that the Sun formed in (a) more quiescent
type of environment," Hester noted, "but we believe that we have
compelling evidence that this is not the case."

It seems that we started in an even rougher neighborhood than first
imagined. In regards to this thread, the original open cluster
containing the Sun and its brethren was a short-lasting feature
(relatively speaking).

¤ Clear skies & a star to steer by! >Michael ¤

10. ## The Sun, in an Open Cluster

Serendipity... A few hours after my previous post I saw a new story in
the journal Science on recent solar origin research , based on work at
Arizona State by Jeff Hester.

You can find the original news release at:
http://www.asu.edu/asunews/research/...h_creation.htm

It seems that the interstellar cloud that gave birth to the Sun was
even more violent than expected. Using data from the Spitzer,
Chandra, and Hubble space telescopes (Save The Hubble!), the team
found that characteristics of the star forming nebula indicate that
among our Sun?s brother and sister stars were a few giant stars.
These giants first cooked the nebula with intense UV radiation, and
then further shook up the neighborhood with supernova explosions.

"People have long imagined that the Sun formed in (a) more quiescent
type of environment," Hester noted, "but we believe that we have
compelling evidence that this is not the case."

It seems that we started in an even rougher neighborhood than first
imagined. In regards to this thread, the original open cluster
containing the Sun and its brethren was a short-lasting feature
(relatively speaking).

¤ Clear skies & a star to steer by! >Michael ¤

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