Starship Asterisk*

Ann wrote:
Many astronomers speculate that the neutron star (or possible black hole) that ought to have been left behind by Supernova 1987A may simply have been "kicked out of the system", flung away from the glowing gaseous remnants, by the explosion itself.

neufer wrote:

icehouse wrote:Where's the black hole that accompanied the supernova?

Supposedly it is hidden in the blackground.

Thus, it is supposed that Geminga is a sort of neutron star: the decaying core of a massive star that exploded as a supernova about 300,000 years ago.
...
The proper motion of Geminga is 178.2 mas/year which corresponds to a projected velocity of 205 kilometers per second.[1] This is very fast for a star, comparable to Barnard's star.

Cygnus X-1 (abbreviated Cyg X-1)[11] is a well known galactic X-ray source[12] in the constellation Cygnus. It was discovered in 1964 during a rocket flight and is one of the strongest X-ray sources seen from Earth, producing a peak X-ray flux density of 2.3 × 10−23 Wm−2Hz−1 (2.3 × 103 Jansky).[13][14] Cygnus X-1 was the first X-ray source widely accepted to be a black hole candidate and it remains among the most studied astronomical objects in its class. It is now estimated to have a mass about 8.7 times the mass of the Sun[6] and has been shown to be too compact to be any known kind of normal star or other likely object besides a black hole. If so, the radius of its event horizon is probably about 26 km.[15]

icehouse wrote:

neufer wrote:

icehouse wrote:Where's the black hole that accompanied the supernova?

Supposedly it is hidden in the blackground.

Really, so its just not visible, theoretically?

icehouse wrote:
I thought at least S. Hawking believes that there would be something to see?

icehouse wrote: It would play tricks on the mind/eye, but something wouldn't look right.
Everything looks perfectly normal. Or, do we believe there is no black hole?

http://en.wikipedia.org/wiki/Gravitational_microlensing wrote:
<<Gravitational microlensing allows the study of objects that emit little or no light. When a distant star or quasar gets sufficiently aligned with a massive compact foreground object, the bending of light due to its gravitational field, as discussed by Einstein in 1915, leads to two distorted unresolved images resulting in an observable magnification. The time-scale of the transient brightening depends on the mass of the foreground object as well as on the relative proper motion between the background 'source' and the foreground 'lens' object.

Since microlensing observations do not rely on radiation received from the lens object, this effect therefore allows astronomers to study massive objects no matter how faint. It is thus an ideal technique to study the galactic population of such faint or dark objects as brown dwarfs, red dwarfs, planets, white dwarfs, neutron stars, black holes, and Massive Compact Halo Objects. Moreover, the microlensing effect is wavelength-independent, allowing to study source objects that emit any kind of electromagnetic radiation.

Microlensing by an isolated object was first detected in 1993. Since then, microlensing has been used to constrain the nature of the dark matter, detect extrasolar planets, study limb darkening in distant stars, constrain the binary star population, and constrain the structure of the Milky Way's disk. Microlensing has also been proposed as a means to find dark objects like brown dwarfs and black holes, study starspots, measure stellar rotation, look for cosmic strings, study globular clusters, and probe quasars, including their accretion disks.

Microlensing is caused by the same physical effect as strong lensing and weak lensing, but it is studied using very different observational techniques. In strong and weak lensing, the mass of the lens is large enough (mass of a galaxy or a galaxy cluster) that the displacement of light by the lens can be resolved with a high resolution telescope such as the Hubble Space Telescope. With microlensing, the lens mass is too low (mass of a planet or a star) for the displacement of light to be observed easily, but the apparent brightening of the source may still be detected. In such a situation, the lens will pass by the source in a reasonable amount of time, seconds to years instead of millions of years. As the alignment changes, the source's apparent brightness changes, and this can be monitored to detect and study the event. Thus, unlike with strong and weak gravitational lenses, a microlensing event is a transient phenomenon.

Unlike with strong and weak lensing, no single observation can establish that microlensing is occurring. Instead the rise and fall of the source brightness must be monitored over time using photometry. This function of brightness versus time is known as a light curve.

Light curve of gravitational microlensing event with its model fitted (red)

---

Simulated strong lensing (black hole going past a background galaxy).

In practice, because the alignment needed is so precise and difficult to predict, microlensing is very rare. Events, therefore, are generally found with surveys, which photometrically monitor tens of millions of potential source stars, every few days for several years. Dense background fields suitable for such surveys are nearby galaxies, such as the Magellanic Clouds and the Andromeda galaxy, and the Milky Way bulge. In each case, the lens population studied comprises the objects between Earth and the source field: for the bulge, the lens population is the Milky Way disk stars, and for external galaxies, the lens population is the Milky Way halo, as well as objects in the other galaxy itself.>>

neufer wrote:

icehouse wrote:Where's the black hole that accompanied the supernova?

Supposedly it is hidden in the blackground.

owlice wrote:

Until a few years ago, astronomers placed the Cygnus Loop, and therefore the Veil Nebula, more than 2,500 light years distant. In 1999, astronomers using the Hubble Space Telescope revised that estimate to 40 percent closer, or 1,470 light years. Nevertheless, uncertainties and assumptions used in making that estimate left some researchers unpersuaded. In 2003, a team of researchers used data from the FUSE satellite to measure accurately the distance to a star lying behind the Loop; this value, of 1,860 light-years, places an upper boundary on the distance to the Loop and provides an independent confirmation of the shorter distance scale.

Source: http://www.daviddarling.info/encycloped ... ebula.html

Unless one is planning to visit, I suspect exact distance doesn't matter all that much.

Until a few years ago, astronomers placed the Cygnus Loop, and therefore the Veil Nebula, more than 2,500 light years distant. In 1999, astronomers using the Hubble Space Telescope revised that estimate to 40 percent closer, or 1,470 light years. Nevertheless, uncertainties and assumptions used in making that estimate left some researchers unpersuaded. In 2003, a team of researchers used data from the FUSE satellite to measure accurately the distance to a star lying behind the Loop; this value, of 1,860 light-years, places an upper boundary on the distance to the Loop and provides an independent confirmation of the shorter distance scale.

icehouse wrote:Where's the black hole that accompanied the supernova?

Joe wrote:Would anyone consider that the Veil Nebula is the remnants of an exploded electric Double Layer that was surrounding the progenitor stellar object ?

owlice wrote:
Dang; I've been outed!

rstevenson wrote:

mikekangas wrote:If the nebula is at an estimated distance of 1500 light years, why did it take 5000 years for the light from the supernova to reach earth?

mikekangas wrote:Well, I read the original wrong. My bad. I see it would take 6500 years for the nebula to expand to its current size.

mikekangas wrote:Well, maybe I shouldn't post here It has taken 5000 years for it to expand to its present size.
What we are seeing is what it looked like 1500 years ago.

I often find that if I talk to myself for a while, I can figure out most anything.

http://www.abacon.com/berk/ica/research.html wrote:

Why Children Talk to Themselves
Scientific American, pp. 78-83.
Berk, L. E. (1994, November).

<<As any parent, teacher, sitter or casual observer will notice, young children talk to themselves - sometimes as much or even more than they talk to other people. Depending on the situation, this private speech can account for 20 to 60 percent of the remarks a child younger than 10 years makes.

In Russia more than six decades ago, Lev S. Vygotsky, a prominent psychologist, first documented the importance of private speech. In fear, Soviet psychologists turned on one another. Some declared Vygotsky a renegade, and several of his colleagues and students split from his circle. The Communist party scheduled a critical "discussion" in which Vygotsky's ideas would be the major target. But in 1934, before Vygotsky could replicate and extend his preliminary studies or defend his position to the party, he died of tuberculosis. Two years later the Communist party banned his published work.

"The most significant moment in the course of intellectual development," Vygotsky wrote, "...occurs when speech and practical activity, two previously completely independent lines of development, converge." Vygotsky proposed that early social communication precipitates private speech. He maintained that social communication gives rise to all uniquely human, higher cognitive processes.

By communicating with mature members ( ) of society ,
children learn to master activities and think in ways that have meaning in their culture.

As the child gains mastery over his or her behavior, private speech need not occur in a fully expanded form; the self, after all, is an extremely understanding listener. Consequently, children omit words and phrases that refer to things they already know about a given situation. They state only those aspects that still seem puzzling. Once their cognitive operations become well practiced, children start to "think words" rather than saying them. Gradually, private speech becomes internalized as silent, inner speech - those conscious dialogues we hold with ourselves while thinking and acting. Nevertheless, the need to engage in private speech never disappears. Whenever we encounter unfamiliar or demanding activities in our lives, private speech resurfaces. It is a tool that helps us overcome obstacles and acquire new skills.>>

orin stepanek wrote:

owlice wrote:

owlice wrote:I'm pretty sure APOD has, indeed, shown the Witch's Broom on Halloween as, I suspect, neufer will demonstrate.

Heh! If he does demonstrate it, that'll be a very cool trick indeed, as I'm wrong about the Witch's Broom having ever been a Halloween APOD. I just checked; it's never been.

I was pretty sure that the Specter In the Eastern Veil was.