Starship Asterisk*

mark swain wrote:http://antwrp.gsfc.nasa.gov/apod/ap070223.html

What are the chances of debris from the above nebular and those as close.
Entering our solar system, or even worse?

mark swain wrote:http://antwrp.gsfc.nasa.gov/apod/ap070223.html
What are the chances of debris from the above nebular and those as close. Entering our solar system, or even worse?

mark swain wrote:The star that created this nebular, http://antwrp.gsfc.nasa.gov/apod/ap070223.html Did so several thousand years ago.
I can see the Debris from our own nebular, as our solar system was once the same. How much Debris from our own nebular got flung out into space? I was just thinking that there are hundreds of these nova/nebular In that past 100 thousand years or even further back, that could send debris( or even worse White dwarfs) our way..;.?

mark swain wrote:I can see the Debris from our own nebular, as our solar system was once the same.

mark swain wrote:I can see the Debris from our own nebular, as our solar system was once the same. How much Debris from our own nebular got flung out into space?

mark swain wrote:I was just thinking that there are hundreds of these nova/nebular In that past 100 thousand years or even further back, that could send debris( or even worse White dwarfs) our way..;.?

Chris Peterson wrote:

mark swain wrote:The star that created this nebular, http://antwrp.gsfc.nasa.gov/apod/ap070223.html Did so several thousand years ago.
I can see the Debris from our own nebular, as our solar system was once the same. How much Debris from our own nebular got flung out into space? I was just thinking that there are hundreds of these nova/nebular In that past 100 thousand years or even further back, that could send debris( or even worse White dwarfs) our way..;.?

The center of mass of the system doesn't move, so the stellar remnant (whether it becomes a white dwarf or not) remains in place. And only a fraction of the original mass is typically lost. So there's nothing but dust- typically in the micrometer size range. Such dust poses no threat, and only passes through the Solar System in very tiny amounts. It's hard to catch, but scientifically valuable when it is caught since it carries clues about other stellar environments.

http://antwrp.gsfc.nasa.gov/apod/ap991127.html wrote:
<<Explanation: Runaway stars are massive stars traveling rapidly through interstellar space. Like a ship plowing through the interstellar medium, runaway star HD 77581 has produced this graceful arcing bow wave or "bow shock" - compressing the gaseous material in its path. Located near the centre of this European Southern Observatory photograph, HD 77581 itself is so bright that it saturates the sensitive camera and produces the spiky cross shape. This star is over 6,000 light-years away in the constellation Vela, and appears to move at over 50 miles per second. What force could set this star in motion? A clue to the answer may lie in its optically invisible companion star, an X-ray bright pulsar known as Vela X-1. This pulsar is clearly the remnant of a supernova explosion ... which seems to have given this massive star and its companion a mighty kick!>>

http://antwrp.gsfc.nasa.gov/apod/ap061124.html wrote:
<<Explanation: Runaway star Alpha Cam has produced this graceful arcing bow wave or bow shock - moving at over 60 kilometers per second and compressing the interstellar material in its path. The bright star above and left of center in this wide (3x2 degree) view, Alpha Cam is about 25-30 times as massive as the Sun, 5 times hotter (30,000 kelvins), and over 500,000 times brighter. About 4,000 light-years away in the long-necked constellation Camelopardalis, the star also produces a strong wind. The bow shock stands off about 10 light-years from the star itself.

What set this star in motion? Astronomers have long thought that Alpha Cam was flung out of a nearby cluster of young hot stars due to gravitational interactions with other cluster members or perhaps by the supernova explosion of a massive companion star.>>

• I'm walkin' in nova rain,
  Comets flyin' and I feel the pain,
  Wishin' you were here by me,
  To end this misery
  And I wonder--
  I wah-wah-wah-wah-wonder,
  Why,
  Why, why, why, why, why she ran away,
  Yes, and I wonder,
  A-where she will stay-ay,
  My little runaway,
  Run, run, run, run, runaway.
  ----------------------------------------------
  Runaway stars
  
  <<A runaway star is one which is moving through space with an abnormally high velocity compared to other stars around it. The velocity is supersonic relative to the surrounding interstellar medium. The proper motion of a runaway star often points exactly away from a stellar association, whose member it therefore once must have been before it was hurled out.
  
  Two possible mechanisms may give rise to a runaway star:
  
  * In the first scenario, a close encounter between two binary systems may result in the disruption of both systems, with some of the stars being ejected at high velocities.
  * In the second scenario, a supernova explosion in a multiple star system can result in the remaining components moving away at high speed.
  
  While both mechanisms are theoretically possible, astronomers generally favour the supernova hypothesis as more likely in practice.
  
  One example of a related set of runaway stars is the case of AE Aurigae, 53 Arietis and Mu Columbae, all of which are moving away from each other at velocities of over 100 km/s (for comparison, the Sun moves through the galaxy at about 20 km/s faster than the local average). Tracing their motions back, their paths intersect near to the Orion Nebula about 2 million years ago. Barnard's Loop is believed to be the remnant of the supernova that launched the other stars.
  .......................................................

  Code: Select all

  
  Explanation: Is star AE Aurigae on fire? Although surrounded by what may look like smoke, the object known as the "flaming star" creates energy primarily by nuclear fusion, like other stars. Fire, typically defined as the rapid molecular acquisition of oxygen, happens only when sufficient oxygen is present and is not important in such high-energy, low-oxygen environments such as stars. The material that appears as smoke is mostly interstellar hydrogen, but does contain smoke-like dark filaments of carbon-rich dust grains. The AE Aurigae region was imaged by the KPNO 0.9-meter telescope and is shown above in false but representative colors. The star AE Aurigae itself is very bright, young, blue, and known as a runaway star since it appears to have been ejected from the Orion Nebula region about 2.7 million years ago.

  .......................................................
  <<AE Aurigae (AE Aur) is a runaway star in the constellation Auriga; it lights the Flaming Star Nebula. AE Aurigae is a blue O-type main sequence dwarf with a mean apparent magnitude of +5.99. It is classified as an Orion type variable star and its brightness varies irregularly between magnitudes +5.78 and +6.08. It is approximately 1460 light-years from Earth. It is a runaway star that might have been ejected during a collision of two binary star groups. This collision, which also is credited with ejecting Mu Columbae and 53 Arietis, has been traced to the Trapezium cluster in the Orion Nebula two million years ago.>>
  
  <<53 Arietis is a variable star of Beta Cephei type, alternatively denoted UW Arietis, in the constellation Aries. Its mean apparent magnitude is 6.13 and its spectral type is O or early B. It is a runaway star, thought to have been produced as a consequence of one of a pair of binary stars colliding. Tracing its motion back shows it was ejected from the Trapezium cluster in the Orion nebula approximately two million years ago.>>
  
  <<Mu Columbae (μ Col / μ Columbae) is a star in the constellation of Columba. It is one of the few O-class stars that is visible to the unaided eye. The star is known to lie approximately 1,300 light years from our solar system (with an error margin of a few hundred light years). This is a relatively fast rotating star that completes a full revolution approximately every 1.5 days. (Compare this to our Sun, which at only 22% of this star's diameter rotates only once every 25.4 days.) This rate of rotation is fairly typical for stars of this class. Based on measurements of proper motion and radial velocity, astronomers know that this star and AE Aurigae are moving away from each other at a relative velocity of over 200 km/s. Their common point of origin intersects with Iota Orionis in the Trapezium cluster, some two and half million years in the past. The most likely scenario that could have created these runaway stars is a collision between two binary star systems, with the stars being ejected along different trajectories radial to the point of intersection.>>
  
  Another example is the X-ray object Vela X-1, where photodigital techniques reveal the presence of a typical supersonic bow shock hyperbola.>>

neufer wrote:One example of a related set of runaway stars is the case of AE Aurigae, 53 Arietis and Mu Columbae, all of which are moving away from each other at velocities of over 100 km/s (for comparison, the Sun moves through the galaxy at about 20 km/s faster than the local average).

http://astroprofspage.com/archives/981 wrote:Arcturus is only 37 light years away. It is moving very quickly, though, relative to the Sun (nearly 122 km/s). Arcturus’ motion is also not in the same direction as most other stars in the area.

apodman wrote:

neufer wrote:One example of a related set of runaway stars is the case of AE Aurigae, 53 Arietis and Mu Columbae, all of which are moving away from each other at velocities of over 100 km/s (for comparison, the Sun moves through the galaxy at about 20 km/s faster than the local average).

While 100 km/s is an impressive velocity for a star, we should point out that it is still only 1/3000 of the speed of light. If a star were ejected at this velocity by an explosion in a multiple star system at the 700 light year distance of the Helix Nebula, it would take 2,100,000 (700x3000) years to get from there to here if it were headed our way. So, Mark, it's not quite time to duck and cover yet.

http://astroprofspage.com/archives/981 wrote:Arcturus is only 37 light years away. It is moving very quickly, though, relative to the Sun (nearly 122 km/s).
Arcturus’ motion is also not in the same direction as most other stars in the area.

• Alpha Boötes is made for walking, and that's just what it'll do
  one of these days Alpha Boötes are gonna walk all over you

apodman wrote:Arcturus is the closest fast-moving star to our solar system, and it's not on a collision course.
So, once again, not yet time to duck and cover.

http://en.wikipedia.org/wiki/Arcturus wrote:
<<Arcturus is notable for its high proper motion, larger than any first magnitude star in the stellar neighborhood other than α Centauri. It is now almost at its closest point to the Sun (i.e., Arcturus radial velocity ~ −5 km/s) , and is moving rapidly (122 km/s) relative to the solar system. Arcturus is thought to be an old disk star, and appears to be moving with a group of 52 other such stars. Its mass is hard to exactly determine, but may be about the same as the Sun, and is no more than 1.5 solar masses. Arcturus is likely to be considerably older than the Sun, and much like what the Sun will be in its red giant phase.>>

neufer wrote:But what if the system center of mass lies outside of the exploding star?

neufer wrote:... the problem would be with a nearby two million year old supernova ... sending some runaway star near enough to our Oort Cloud to induce a surge of comets.

Chris Peterson wrote:

neufer wrote:But what if the system center of mass lies outside of the exploding star?

Well, that's possible if you're talking about the center of mass of the entire stellar system, and it consists of multiple stars. But I was talking about "system" in the physical sense, applied to the exploding star itself. And after it explodes, its center of mass is going to pretty much be doing whatever it was before the explosion (recognizing that there are some asymmetries in supernovas, so there might be some fairly small velocity offset applied- but certainly no white dwarfs are going to come hurling out of a supernova).

http://www.iop.org/EJ/abstract/0004-637X/561/2/930 wrote:
The Distance to the Vela Pulsar Gauged with Hubble Space Telescope Parallax Observations*
P. A. Caraveo et al 2001 ApJ 561 930-937 doi: 10.1086/323377 Help

ABSTRACT. The distance to the Vela pulsar (PSR B0833-45) has been traditionally assumed to be 500 pc. Although affected by a significant uncertainty, this value stuck to both the pulsar and the supernova remnant. In an effort to obtain a model-free distance measurement, we have applied high-resolution astrometry to the pulsar V ~ 23.6 optical counterpart. Using a set of five Hubble Space Telescope Wide Field Planetary Camera 2 observations, we have obtained the first optical measurement of the annual parallax of the Vela pulsar. The parallax turns out to be 3.4 ± 0.7 mas, implying a distance of 294 pc, i.e., a value significantly lower than previously believed. This affects the estimate of the pulsar absolute luminosity and of its emission efficiency at various wavelengths and confirms the exceptionally high value of Ne toward the Vela pulsar. Finally, the complete parallax database allows for a better measurement of the Vela pulsar proper motion [μα cos(δ) = -37.2 ± 1.2 mas yr-1; μδ = 28.2 ± 1.3 mas yr-1 after correcting for the peculiar motion of the Sun], which, at the parallax distance, implies a transverse velocity of approx 65 km s-1. Moreover, the proper-motion position angle appears especially well aligned with the axis of symmetry of the X-ray nebula as seen by Chandra. Such an alignment allows us to assess the space velocity of the Vela pulsar to be 81 km s-1.

http://antwrp.gsfc.nasa.gov/apod/ap000609.html wrote:
Explanation: This stunning image from the orbiting Chandra X-ray Observatory is centered on the Vela pulsar -- the collapsed stellar core within the Vela supernova remnant some 800 light-years distant. The Vela pulsar is a neutron star. More massive than the Sun, it has the density of an atomic nucleus. About 12 miles in diameter it spins 10 times a second as it hurtles through the supernova debris cloud. The pulsar's electric and magnetic fields accelerate particles to nearly the speed of light, powering the compact x-ray emission nebula revealed in the Chandra picture. The cosmic crossbow shape is over 0.2 light-years across, composed of an arrow-like jet emanating from the polar region of the neutron star and bow-like inner and outer arcs believed to be the edges of tilted rings of x-ray emitting high energy particles. Impressively, the swept back compact nebula indicates the neutron star is moving up and to the right in this picture, exactly along the direction of the x-ray jet. The Vela pulsar (and associated supernova remnant) was created by a massive star which exploded over 10,000 years ago. Its awesome x-ray rings and jet are reminiscent of another well-known pulsar powered system, the Crab Nebula.

http://antwrp.gsfc.nasa.gov/apod/ap030703.html wrote:
Explanation: The Vela pulsar is a neutron star born over 10,000 years ago in a massive supernova explosion. Above, false-color x-ray images from the Chandra Observatory reveal details of this remnant pulsar's x-ray bright nebula along with emission from a spectacular jet of high-energy particles. In this time-lapse series of pictures, the jet seems to dance around very much like an out-of-control firehose, shooting along the pulsar's direction of motion (toward the top right corner) to a length of about half a light-year while whipping back and forth at about half the speed of light. Highly magnetized and spinning over 10 times a second, the Vela pulsar is thought of as a cosmic high-voltage generator, powering the x-ray nebula and dynamic cosmic jet. A mere 800 light-years away the pulsar itself is located near the lower left corner in the four panels.

apodman wrote:

neufer wrote:... the problem would be with a nearby two million year old supernova ... sending some runaway star near enough to our Oort Cloud to induce a surge of comets.

Yes. If such a star were giving off visible light, we would know about it. And if it were sending out photons in a non-visible part of the spectrum, we would also know about it. Even a neutron star should be detectable a couple of ways: it is hot, and should be sending out photons at infrared wavelengths; and, it is magnetized and rotating, and so should be sending out something high-frequency, maybe x-rays? I don't know the actual frequency range offhand. Do we know of any types of objects with stellar mass that could be headed our way and not be detectable by currently available means? How about a high speed small black hole - do we know a mechanism or scenario that could fling one? Even that should be detectable by some sort of distortion or lensing effect on our view of objects beyond it, even if it were on such a direct course that it had zero proper motion (always stayed in the same spot in the stellar background). Of course, there's always the "golden bb" - something (maybe a cool brown dwarf) outside our detection range coming incredibly fast with great aim.

neufer wrote:No...but a spinning magnetic neutron star with asymmetric jets
(heavy protons out one direction, radiant electrons out the other???)
might well launch itself out of an isolated supernova.

Chris Peterson wrote:

neufer wrote:No...but a spinning magnetic neutron star with asymmetric jets
(heavy protons out one direction, radiant electrons out the other???)
might well launch itself out of an isolated supernova.

I guess anything is possible. But I've never heard of such a thing. Every supernova remnant I've seen has whatever is left of the original star sitting pretty near the middle. And that makes some sense, given the mass of the object and the sort of reaction required to accelerate it significantly. I'm not sure how to interpret the Vela information- it is unclear to me that the currently observed motion is the result of the supernova, as opposed to whatever its original relative velocity was. In any case, we're only talking about tens of kilometers per second, which is certainly very slow on any cosmic scale. Not what I'd call hurtling... <g>

http://antwrp.gsfc.nasa.gov/apod/ap070213.html wrote:
Explanation: The above image captures much of that filamentary and gigantic shock in visible light, spanning almost 100 light years and appearing twenty times the diameter of the full moon. Remaining at the center of the Vela Supernova Remnant is a pulsar, a star as dense as nuclear matter that completely rotates more than ten times in a single second.

• [Finnegans Wake 5.17] Our cubehouse still rocks as earwitness to
  the thunder of his arafatas but we hear also through successive
  ages that shebby choruysh of unkalified muzzlenimiissilehims that
  would blackguardise the whitestone ever hurtleturtled out of heaven.

apodman wrote:Death Star? Anything with a simple Romulan cloaking device will do.
---
P.S. My conjecture on the detectability of a neutron star was quoted before my last edit.
It's still not quite right, but it's better. Should have mentioned "pulsar".

http://en.wikipedia.org/wiki/Neutron_star wrote:
<<The temperature inside a newly formed neutron star is from around 10^11 to 10^12 Kelvin. However, the huge number of neutrinos it emits carries away so much energy that the temperature falls within a few years to around 1 million Kelvin. Even at 1 million Kelvin, most of the light generated by a neutron star is in X-rays. In visible light, neutron stars probably radiate approximately the same energy in all parts of visible spectrum, and therefore appear white.

At present there are about 2000 known neutron stars in the Milky Way and the Magellanic Clouds, the majority of which have been detected as radio pulsars. The population of neutron stars is concentrated along the disk of the Milky Way although the spread perpendicular to the disk is fairly large. The reason for this spread is that neutron stars are born with high speeds (400 km/s) as a result of an imparted momentum-kick from an asymmetry during the supernova explosion process. The closest known neutron star is PSR J0108-1431 at a distance of about 85 parsecs (or 280 light years). Another nearby neutron star is RX J185635-3754 but observations using the Chandra X-ray Observatory in 2002 appear to show that its distance is greater—about 450 light-years.>>

Abstract: Among extinct radioactivities present in meteorites, 60Fe (t1/2 = 1.49 Myr) plays a key role as a high-resolution chronometer, a heat source in planetesimals, and a fingerprint of the astrophysical setting of solar system formation. A critical issue with 60Fe is that it could have been heterogeneously distributed in the protoplanetary disk, calling into question the efficiency of mixing in the solar nebula or the timing of 60Fe injection relative to planetesimal formation. If this were the case, one would expect meteorites that did not incorporate 60Fe (either because of late injection or incomplete mixing) to show 60Ni deficits (from lack of 60Fe decay) and collateral effects on other neutron-rich isotopes of Fe and Ni (coproduced with 60Fe in core-collapse supernovae and AGB-stars). Here, we show that measured iron meteorites and chondrites have Fe and Ni isotopic compositions identical to Earth. This demonstrates that 60Fe must have been injected into the protosolar nebula and mixed to less than 10 % heterogeneity before formation of planetary bodies.

harry wrote:There is a theory that our solar sytem was from a supernova that left a compact object which developed into our Sun and left the debri of planets and rocks.

There is also a theory that every few hundred million years our solar sytem passes through a Nebula. This topic was discussed sometime ago.

Chris Peterson wrote:

harry wrote:There is also a theory that every few hundred million years our solar system passes through a Nebula. This topic was discussed sometime ago.

Not exactly. There are clouds of material within our galaxy. These are short lived- certainly less than hundreds of millions of years. They form from the debris of exploded stars, and dissipate or collapse into new stars. The Solar System is quite close to some areas like this right now, and statistically there's no doubt it passes through some from time to time (not periodically, though). Not that this would be expected to have much effect on anything.

http://en.wikipedia.org/wiki/Nemesis_(star) wrote:
<<In 1984 paleontologists David Raup and Jack Sepkoski published a paper claiming that they had identified a statistical periodicity in extinction rates over the last 250 million years using various forms of time series analysis. They focused on the extinction intensity of fossil families of marine vertebrates, invertebrates, and protozoans, identifying 12 extinction events over the time period in question. The average time interval between extinction events was determined as 26 million years. At the time, two of the identified extinction events (Cretaceous-Tertiary and Late Eocene) could be shown to coincide with large impact events. Although Raup and Sepkoski could not identify the cause of their supposed periodicity, they suggested that there might be a non-terrestrial connection. Matese and Whitman have suggested that the supposed extinction periodicity might be caused by the solar system oscillating across the galactic plane of the Milky Way. These oscillations may lead to gravitational disturbances in the Oort cloud. However, the period of oscillation is not well-constrained observationally, and may differ from the needed 26 million years by as much as 40%.>>