A Space & astronomy forum. SpaceBanter.com

Go Back   Home » SpaceBanter.com forum » Astronomy and Astrophysics » Astronomy Misc
Site Map Home Authors List Search Today's Posts Mark Forums Read Web Partners

What if hypervelocity star came near Sun?



 
 
Thread Tools Display Modes
  #1  
Old November 23rd 06, 06:12 AM posted to alt.astronomy,rec.arts.sf.science,sci.astro,sci.space.policy,soc.history.what-if
tracy
external usenet poster
 
Posts: 6
Default What if hypervelocity star came near Sun?

According to this article, the mysterious super-high speed stars are
more numerous and fastest than previously though. What if one of these
"hypervelocity" stars came through Sun's neighborhood? How dangerous
it could be for life on Earth?

What would be safe distance a star moving at about 700 - 1000 km/s
could get near Sun without disrupting the planetary system?



http://space.newscientist.com/channe...ays-stars.html


Puny black holes can eject Milky Way's stars

NewScientist.com news service

David Shiga




Tiny black holes near the galaxy's centre can fling stars out of the
Milky Way at break-neck speeds, a new study suggests. Previously, only
the supermassive black hole there was thought to be able to produce
these "hypervelocity" stars.

The researchers say the small black holes could actually be ejecting
more stars than the central black hole does on its own, and that
observing the stars could shed light on the elusive population of
mini-black holes themselves.

Physicist Jack Hills at Los Alamos National Laboratory in New Mexico,
US, predicted in 1988 that the monster black hole at our galaxy's
centre should disrupt pairs of stars, capturing one and launching the
other out of the galaxy altogether. Since 2004, astronomers have found
nine stars travelling at high speed out of our galaxy - all
presumably flung there by the giant black hole, which weighs about 3.6
million times the mass of the Sun.

But a new study suggests that many of the ejected stars are getting
kicked out by a swarm of much smaller black holes at the galaxy's
centre. The study was carried out by Ryan O'Leary and Avi Loeb, both at
the Harvard Smithsonian Center for Astrophysics in Cambridge,
Massachusetts, US.

Close encounters

The smaller black holes are about 10 times more massive than the Sun.
Some studies suggest as many as 25,000 small black holes may orbit the
supermassive black hole at the galaxy's centre, having migrated there
from other parts of the galaxy after being nudged out of their original
orbits by passing stars.

When one of these little black holes near the galactic centre passes
very close to a star, it can sometimes fling the star out of the
galaxy, while itself moving closer to the supermassive black hole, the
study says.

This process could eject stars at an even greater rate than the
disruption of binary stars by the supermassive black hole itself, Loeb
says. "The rate could account for a substantial fraction or maybe most
of the events we have seen so far," he told New Scientist.

If so, studying the sheer number of hypervelocity stars, as well as
their trajectories and speeds, could help astronomers determine how
many black holes are there and how they are distributed in space, Loeb
says.

These have proven to be elusive subjects of study because existing
telescopes do not have the resolution to see within a fraction of a
light year of the central supermassive black hole, where these little
black holes are thought to be concentrated most heavily.

Speed limit

Margaret Geller, an astronomer at the Smithsonian Astrophysical
Observatory who was on the team that found the first hypervelocity star
in 2004, says encounters with small black holes could account for some
of the ejected stars.

She says it is not likely to account for all such stars, however. "It's
tough for them to get the highest velocity objects," she told New
Scientist.

The fastest known hypervelocity star is moving at 709 kilometres per
second with respect to the galaxy. The star would have been slowed by
the galaxy's gravity on its way out, so it must have been moving at
about 1200 kilometres per second initially. But Loeb argues that small
black holes can eject stars at up to 2000 kilometres per second, fast
enough to explain all known hypervelocity stars.

He and Geller agree that searching for even faster stars would be a
good way to test the small black hole mechanism. The supermassive black
hole could fling stars out with starting velocities of 4000 kilometres
per second, faster than anything the small black holes could account
for, Loeb says.

"If the velocity distribution does extend to high speeds, then it
argues for the other mechanism," he says.

  #2  
Old November 23rd 06, 07:02 AM posted to alt.astronomy,rec.arts.sf.science,sci.astro,sci.space.policy,soc.history.what-if
Sorcerer[_4_]
external usenet poster
 
Posts: 326
Default What if hypervelocity star came near Sun?


"tracy" wrote in message oups.com...
| According to this article, the mysterious super-high speed stars are
| more numerous and fastest than previously though. What if one of these
| "hypervelocity" stars came through Sun's neighborhood?

In hypothetical sentences introduced by 'if' and referring to
past time, where conditions are to be deemed 'unfulfilled',
the verb will regularly be found in the pluperfect subjunctive,
in both protasis and apodosis.
-- Donet, "Principles of Elementary Latin Syntax"



| How dangerous
| it could be for life on Earth?

About the same as a bacterium in a crematorium. It might even be fatal.


|
| What would be safe distance a star moving at about 700 - 1000 km/s
| could get near Sun without disrupting the planetary system?

The speed is irrelevant, presence is.
You don't seem to grasp the scale of the Universe or even the scale
of the Solar System.
Suppose you have a cluster of 4 pixels (dots) in the middle of your
monitor screen to represent the sun, like this:

---- o ---- (Sun, drawn too big)

Then
|
|
|
| -- . ---- (Mercury)
|
|
|
|
| -- . -- (Venus)
|
|
|
|
| -- ' -- (Earth and Moon)


Jupiter (still a dot -- . --- ) is about where your ceiling is.
Saturn is then in your kitchen, the NEAREST star is at the end of the street,
and the imaginary black hole at the galactic centre is in the next city.
You have a far better chance of winning the lottery than meeting another
star up close and personal.
Androcles

  #3  
Old November 23rd 06, 08:27 AM posted to sci.astro
Sao 67174
external usenet poster
 
Posts: 16
Default What if hypervelocity star came near Sun?

"tracy" ha scritto nel messaggio
oups.com...
According to this article, the mysterious super-high speed stars are
more numerous and fastest than previously though. What if one of these
"hypervelocity" stars came through Sun's neighborhood? How dangerous
it could be for life on Earth?

What would be safe distance a star moving at about 700 - 1000 km/s
could get near Sun without disrupting the planetary system?

http://space.newscientist.com/channe...ays-stars.html

Puny black holes can eject Milky Way's stars

NewScientist.com news service

David Shiga


CUT

Sorry for bad English.

Alfa Centaur sistem (three stars) it's at 4.4 l.y. (around 200,000
A.U.), it's not a problem for Solar Sistem, Barnard Star shall be
in the future a 3 l.y. and too it shall be not a problem for Solar Sistem,
then when a star is certainly dangerous for our sistem? When its
(minimal) distance from the Sun is 60 A.U., it can to send Neptune
in a parabolic orbit and disturb heavy the orbit of other
planets, so much that the life on the Earth can to be seriously
in danger, and this if the star has the same mass of the Sun, if
its mass is biggest it can to do the same from a biggest distance:
for to have a save life on the Earth a star with the same
mass of Sun must to be distant at minimum some hundred
of A.U., the Astronomer think that similar passages occured
in the last 4.5 billion of years around 10-20 time in the past.
The speed it's too important: it's better a quick
star that a slow star because more shall be the time at
a little distance from the Sun more are possibilities that
the planets should be perturbed, and an other factor it's
the inclination of its path respect Solar Sistem,
the inclination influence the duration of the meeting
with the Solar Sistem and then the following effects.
In all cases a star passing at some thousands od A.U.
fron the Sun it do a fall of comet toward the Sun
from Oort cloud with possibility that some fall on the
Earth, there are evidence that 2 stars in the recent
past accross the Oort cloud.
Sao 67174



  #4  
Old November 23rd 06, 09:57 AM posted to alt.astronomy,rec.arts.sf.science,sci.astro,sci.space.policy
Stan Engel
external usenet poster
 
Posts: 17
Default What if hypervelocity star came near Sun?


"tracy" wrote in message
oups.com...
According to this article, the mysterious super-high
speed stars are more numerous and fastest than
previously though.


According to the group charter, this is off-topic for
soc.history.what-if.

What if one of these "hypervelocity" stars came through
Sun's neighborhood?


It would be a bad thing. However, this is all off-topic.



--
Posted via a free Usenet account from http://www.teranews.com

  #5  
Old November 23rd 06, 11:56 AM posted to alt.astronomy,rec.arts.sf.science,sci.astro,sci.space.policy,soc.history.what-if
Matt Giwer
external usenet poster
 
Posts: 523
Default What if hypervelocity star came near Sun?

tracy wrote:
According to this article, the mysterious super-high speed stars are
more numerous and fastest than previously though. What if one of these
"hypervelocity" stars came through Sun's neighborhood? How dangerous
it could be for life on Earth?


What would be safe distance a star moving at about 700 - 1000 km/s
could get near Sun without disrupting the planetary system?


http://space.newscientist.com/channe...ays-stars.html
...


Lets cut it as this point and look at the requirements for an effect. First
passing through a solar system is very low probability. Second it has to pass
close enough to a planet to impart enough momentum to do something significant.
Those odds are also very low. Very significant is very very low.

But as to what would happen you need a serious program to deal with orbital
mechanics of the planets and then fly a few thousand through the solar system
and get a feel for the results.

Some simple consideration, on average "half" the planets are going to be on the
wrong side of the sun to be seriously affected. The closer to the sun the less
affected. Being tossed out of the solar system is much more likely than falling
into the sun but equally likely with a highly elliptic orbit.

There is really not good answer other than learn the orbital mechanics and
think it through for yourself. There is no way to give a decent answer without
the listener knowing the subject.

--
Consider Jews have said they will continue to try to murder Nasrallah, the
leader of Hezbollah, but he has not said he will try to murder the leader of
Israel. Who is the most civilized?
-- The Iron Webmaster, 3704
nizkor http://www.giwersworld.org/nizkook/nizkook.phtml
Mission Accomplished http://www.giwersworld.org/opinion/mission.phtml a12
  #6  
Old November 23rd 06, 04:28 PM posted to alt.astronomy,rec.arts.sf.science,sci.astro,sci.space.policy,soc.history.what-if
Frank Glover[_1_]
external usenet poster
 
Posts: 353
Default What if hypervelocity star came near Sun?

tracy wrote:
According to this article, the mysterious super-high speed stars are
more numerous and fastest than previously though. What if one of these
"hypervelocity" stars came through Sun's neighborhood? How dangerous
it could be for life on Earth?

What would be safe distance a star moving at about 700 - 1000 km/s
could get near Sun without disrupting the planetary system?



Depends on the mass of the star, just how fast, perhaps its angle
with respect to the plane of the eclptic and how much perturbation (you
can have detectable, but harmless changes) you consider disruptive.

All in all though, I'd say having another star (or stellar mass
object) pass within tens of billions of miles is not a good thing. Even
just stirring up the Oort Cloud or KBOs could result in signifigant
matter falling into the inner sloar system, and some of those rocks
could have our name on it....


--

Frank

You know what to remove to reply...

Check out my web page: http://www.geocities.com/stardolphin1/link2.htm

"To confine our attention to terrestrial matters would be to limit the
human spirit."
- Stephen Hawking
  #7  
Old November 23rd 06, 05:54 PM posted to alt.astronomy,rec.arts.sf.science,sci.astro,sci.space.policy,soc.history.what-if
[email protected]
external usenet poster
 
Posts: 51
Default What if hypervelocity star came near Sun?


Sorcerer kirjutas:
"tracy" wrote in message oups.com...
| According to this article, the mysterious super-high speed stars are
| more numerous and fastest than previously though. What if one of these
| "hypervelocity" stars came through Sun's neighborhood?

In hypothetical sentences introduced by 'if' and referring to
past time, where conditions are to be deemed 'unfulfilled',
the verb will regularly be found in the pluperfect subjunctive,
in both protasis and apodosis.
-- Donet, "Principles of Elementary Latin Syntax"



| How dangerous
| it could be for life on Earth?

About the same as a bacterium in a crematorium. It might even be fatal.


|
| What would be safe distance a star moving at about 700 - 1000 km/s
| could get near Sun without disrupting the planetary system?

The speed is irrelevant, presence is.


Actually, the speed is relevant.
The Solar System might - at a very low probability as explained by
previous poster below - experience a close encounter with a star.

It might be a disc star like Toliman or Sirius at a rather low relative
speed, or a halo star like Barnard Runner or Arcturus at higher
velocity, or a rare hypervelocity star ejected from Galactic core at
yet faster speed.

The faster the star is, the smaller the danger. After all, what
disrupts the Solar System is the gravity of the star. The gravitational
acceleration at a given distance is independent of the speed of the
disturbing star. But the faster the star, the less time it spends near
Solar System, and the less momentum the planets will accumulate.

You don't seem to grasp the scale of the Universe or even the scale
of the Solar System.
Suppose you have a cluster of 4 pixels (dots) in the middle of your
monitor screen to represent the sun, like this:

---- o ---- (Sun, drawn too big)

Then
|
|
|
| -- . ---- (Mercury)
|
|
|
|
| -- . -- (Venus)
|
|
|
|
| -- ' -- (Earth and Moon)


Jupiter (still a dot -- . --- ) is about where your ceiling is.
Saturn is then in your kitchen, the NEAREST star is at the end of the street,
and the imaginary black hole at the galactic centre is in the next city.
You have a far better chance of winning the lottery than meeting another
star up close and personal.
Androcles


  #8  
Old November 23rd 06, 06:36 PM posted to alt.astronomy,rec.arts.sf.science,sci.astro,sci.space.policy,soc.history.what-if
Sorcerer[_4_]
external usenet poster
 
Posts: 326
Default What if hypervelocity star came near Sun?


wrote in message ups.com...
|
| Sorcerer kirjutas:
| "tracy" wrote in message oups.com...
| | According to this article, the mysterious super-high speed stars are
| | more numerous and fastest than previously though. What if one of these
| | "hypervelocity" stars came through Sun's neighborhood?
|
| In hypothetical sentences introduced by 'if' and referring to
| past time, where conditions are to be deemed 'unfulfilled',
| the verb will regularly be found in the pluperfect subjunctive,
| in both protasis and apodosis.
| -- Donet, "Principles of Elementary Latin Syntax"
|
|
|
| | How dangerous
| | it could be for life on Earth?
|
| About the same as a bacterium in a crematorium. It might even be fatal.
|
|
| |
| | What would be safe distance a star moving at about 700 - 1000 km/s
| | could get near Sun without disrupting the planetary system?
|
| The speed is irrelevant, presence is.
|
| Actually, the speed is relevant.
| The Solar System might - at a very low probability as explained by
| previous poster below - experience a close encounter with a star.
|
| It might be a disc star like Toliman or Sirius at a rather low relative
| speed, or a halo star like Barnard Runner or Arcturus at higher
| velocity, or a rare hypervelocity star ejected from Galactic core at
| yet faster speed.
|
| The faster the star is, the smaller the danger. After all, what
| disrupts the Solar System is the gravity of the star.

| The gravitational
| acceleration at a given distance is independent of the speed of the
| disturbing star. But the faster the star, the less time it spends near
| Solar System, and the less momentum the planets will accumulate.

"Danger" is not a word that is relevant except to human beings.
ANY close encounter would be fatal, independent of velocity.
We are talking about another sun, not a puny comet colliding with
Jupiter.
http://www2.jpl.nasa.gov/sl9/gif/sl9_home.gif

Perhaps this might give you some idea of the delicate balance
we have:
http://faculty.ifmo.ru/butikov/Proje...llection1.html
Pay particular attention to example 8. At first it looks stable,
but it isn't.
That should give you a pretty good idea of what happened
to Shoemaker-Levy.
Androcles



|
| You don't seem to grasp the scale of the Universe or even the scale
| of the Solar System.
| Suppose you have a cluster of 4 pixels (dots) in the middle of your
| monitor screen to represent the sun, like this:
|
| ---- o ---- (Sun, drawn too big)
|
| Then
| |
| |
| |
| | -- . ---- (Mercury)
| |
| |
| |
| |
| | -- . -- (Venus)
| |
| |
| |
| |
| | -- ' -- (Earth and Moon)
|
|
| Jupiter (still a dot -- . --- ) is about where your ceiling is.
| Saturn is then in your kitchen, the NEAREST star is at the end of the street,
| and the imaginary black hole at the galactic centre is in the next city.
| You have a far better chance of winning the lottery than meeting another
| star up close and personal.
| Androcles
|
  #9  
Old November 23rd 06, 09:27 PM posted to alt.astronomy,rec.arts.sf.science,sci.astro,sci.space.policy,soc.history.what-if
paulaireilly
external usenet poster
 
Posts: 6
Default What if hypervelocity star came near Sun?


Sorcerer wrote:
| How dangerous
| it could be for life on Earth?


Depends on the star and how close it passes. It's a very unlikely
event, but if it
is close enough to disrupt orbits, that would be bad. Similar to "If
someone fires
a bullet at random somewhere on your planet, how dangerous is that to
you?"
Or:
About the same as a bacterium in a crematorium. It might even be fatal.


|
| What would be safe distance a star moving at about 700 - 1000 km/s
| could get near Sun without disrupting the planetary system?


Depends on size of the star. Tens of AU or more.



Now here is why I posted. I agree with the essence of the following
bit,
but have a slight correction:

The speed is irrelevant, presence is.
You don't seem to grasp the scale of the Universe or even the scale
of the Solar System.
Suppose you have a cluster of 4 pixels (dots) in the middle of your
monitor screen to represent the sun, like this:

---- o ---- (Sun, drawn too big)

Then
|
|
|
| -- . ---- (Mercury)
|
|
|
|
| -- . -- (Venus)
|
|
|
|
| -- ' -- (Earth and Moon)


Jupiter (still a dot -- . --- ) is about where your ceiling is.


Earth is about 10 cm from the Sun on my screen. So Jupiter would be
about 52 cm away, not near the ceiling really.

Saturn is then in your kitchen,


Saturn is 1m away, approximately.

the NEAREST star is at the end of the street,


The nearest star other than the Sun is Proxima Centauri, about 4 *
10^16 m
away, and on this 1:1,500,000,000,000 scale that comes out to a bit
under
3 * 10^4 m away. 25 km or so... a bit further than the end of the
block.

This only reinforces the point the author was making.

and the imaginary black hole at the galactic centre is in the next city.


More like 200,000 km away. Imagine someone halfway to the Moon firing
a
BB at random; what is the chance he'll hit a particular dinner plate on
Earth?

You have a far better chance of winning the lottery than meeting another
star up close and personal.


Agreed, only by several orders of magnitude more so. At least, around
here.
(In the central parsec of the Galaxy, stars may well collide once in a
while...)

Androcles


  #10  
Old November 23rd 06, 11:44 PM posted to alt.astronomy,rec.arts.sf.science,sci.astro,sci.space.policy,soc.history.what-if
Sorcerer[_4_]
external usenet poster
 
Posts: 326
Default What if hypervelocity star came near Sun?


"paulaireilly" wrote in message oups.com...
| How dangerous
| it could be for life on Earth?

Paul, what is "it" and why are you asking?
Ignorant snipping will lead people to misunderstanding who said what,
don't you think?
Androcles

 




Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
What if hypervelocity star came near Sun? tracy Policy 81 December 4th 06 09:25 PM
Everyone That Sees The nightbat Star Officer Star Glow Cap Falls In LoveWith Them! nightbat Misc 0 September 26th 05 12:43 AM
Cluster and Double Star see star crack during massive 'starquake'(Forwarded) Andrew Yee Astronomy Misc 0 September 22nd 05 04:37 PM
Online star map / star chart / star atlas Excalibur Astronomy Misc 3 September 12th 03 07:25 PM
Online star map / star chart / star atlas Excalibur Amateur Astronomy 3 September 12th 03 07:25 PM


All times are GMT +1. The time now is 09:48 PM.


Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Copyright ©2004-2024 SpaceBanter.com.
The comments are property of their posters.