from doppler shifts can distinguish the mass outflow in a typical T Tauri star from that in a bipolar outflow?
201752
T Tauri stars have bipolar outflows, to the best of my knowledge.  They form Herbig-Haro Objects when the collide with slower matter from the interstellar medium.  They might not always show up with T Tauri stars because of nearby nebula, but my astronomy professor (James Kaler, UIUC) assures me that they are there.\n\nIf you're talking about mass outflows that the T Tauri stars outputs in addition to the bipolar flows, then I'm sure Doppler shifting can be used.  The speeds for the regular outflows should be pretty similar to that of the T Tauri itself, whereas the bipolar flows (depending on orientation to earth, of course) should be much higher.  I hope this helped!
664758
Not possible. The one which contains more mass may be able to leach matter from the smaller one if it is close enough. All of the matter from the smaller one must pass the EVENT HORIZON of the larger one. No two stars ever actually touch, but may rob matter from one of smaller mass.
672020
I googled "biggest star" and the first hit was the one below. The answer is the Pistol Star, which I never heard of before. Wikipedia also mentions Eta Carinae, which I have heard of before.
275713
Maybe the program 'Cartes du Ciel' can help you. You can download it for free in English at:\n\nhttp://www.stargazing.net/astropc/index.html
391876
The North Star (Polaris) is at the end of the handle of the Little Dipper. The two stars at the end of the Big Dipper's bowl point to it.\n\nMost of the other stars of the Little Dipper are fairly dim, so you could have trouble making it out unless you're well away from urban light pollution. Polaris itself is almost as bright as the brightest stars in the Big Dipper, and should be easy to see. So you're probably just not looking in the right place.
431684
Well, the helium is all accumulating in the core where the fusion takes place.  In most starts there is little or no convection between the core an the outer envelope.  \n\nLower mass stars do fuse more slowly and live longer.  Indeed, by losing mass, Cygnus' X-1 companion will have a longer lifetime than it would otherwise. \n\nIf you read about interacting binaries you will learn more about this phenomenon.  Note that for a star to have filled its Roche lobe and start losing mass, it nearly always already has to be off the main sequence (and starting to puff up) and closing in on the end of its life, though one can imagine a circumstance where a compact companion has come closer to the surviving star and begins stripping matter from it while it is still on the main sequence.\n\nTry looking up "blue stragglers" and "cataclysimic binaries" for more information on this.
585529
it is true, most of the visible star systems in our galaxy are binary (not 98%, more like 80% but that's still a lot). however, our sun is very unique in that it is just a single star system. We know this because the eccentricity (how much of a deviation from a perfect circle, with e=0 being a circle and 0<e<1 being an ellipse) of the planets within the solar system (sans Pluto) and really really close to e=0.\n\nAs you head to the outer planets, we see that the eccentricities increase substantially (but are still small, like e=.09 or something). This is obviously due to large bodies afflicting their gravitational pull. It was this theory that led to the discovery of Uranus, Neptune, and Pluto.\n\nNow we come to Pluto. Pluto's orbit is strange because a lot of energy came into play to put it in that orbit. The likelihood is due to the fact that Pluto was one of Neptune's moons or a rogue mass body from the early formation of the solar system. \n\nThe decision was reached to that because we know from endless observations that there is nothing close by that can produce enough of a gravitational pull to cause Pluto's orbit to be that offset. Even if it were dead, we would've still noticed it by now (if it were present) due to strong gravitational pulls from a single source. But none have been found. \n\nThe only reason why this belief is even more cemented now is due to the discovery of extrasolar planets within binary star systems that have insane eccentricities. This does not cement the theory, but adds a significant amount of evidence that our solar system is an anomaly in the vastness of space.
429273
Sirius B is one of the most massive white dwarf known.  Its volume is about the same as Earth, but the mass is comparable to that of the Sun. Since the mass of the Sun is approximately 333000 times that of the Earth, and that Earth has a density of 5.5, we have a specific density of 1800000 for Sirius B. That means 1 cubic cm of Sirius B should have a mass of 1800000 g,\nor 1800 kg, or 1.8 tonne (about 2 tons). So, this is not quite the 50 tons you were told.\nThat said, one may have been talking about the *core* of the star, where density is evidently a lot higher than the average for the whole star.
509374
This is something related to what is called the Doppler effect. You can experience it first hand when a police car is approaching and then going away: the sound of the siren is higher pitched when it is getting closer, and lower pitched when it goes away.\nThe same effect occurs with light.  A light emitter -- a star of a whole galaxy -- will seem to be bluer (higher frequency) if it is getting closer, or redder if it is moving away.  How much bluer or redder is called blue (or red) shift. If one knows what should be the neutral color of the light (and we do, thanks to the spectroscopic lines of emission) then the speed of the object can be derived by said amount of blue or red shift.  This is what allowed Edwin Hubble to deduct that the universe was in expansion, as most galaxies have a redshift that is greater the further they are.
219354
I admire mathematician's concise answers, but in this case some additional explanation may be due:\n\nWhen a wave is partially transmitted and partially reflected the two outgoing waves are shifted in phase from the incident wave. If energy or probability is to be conserved, the difference between the two phase shifts is pi/2 (90°). In this diagram each of the two possible outgoing  beams consist of components from two paths (R=Reflection,T=Transmission):\n\nOutgoing Horizontal: TRR + RRT\nOutgoing Vertical: TRT + RRR\n\nIn the first case the relative phase shift between the two components is 0 and in the second case it's pi (180°) ==> the two components are negatives of each other and interfere destructively.
591784
Through the study of other stars 'wobble' within our own galaxy, we have detected planets larger than Jupiter, we believe.  Though, this is through a calculation with the doppler effect.  So to play it safe, as far as we know now it is Jupiter.  But to say that this will always be true would be bold and naive.
355185
Infrared.  The more massive the main sequence star, the hotter it is.  The hotter an object is, the more energetic its peak wavelength is.
27748
Interesting. I vaguely remember a "great attractor" from chaos theory, but what I find when I look it up now is that it refers to a cluster of galaxies, "in the direction of Centaurus and Hydra" where nobody is sure why they're grouped like that.\n\nHere's a direct quote from another source though which I think directly addresses what you're asking about: The galaxy rotational problem refers to the phenomenon of the descrepency between the observed rotational motion of the matter of the galactic disc from the predictions of Newtonian dynamics. (See links below and search for "12.25.I".)\n\nI think in layman's terms what they're boggling about is the "bar" shape that occurs in most galaxies, our own apparently included. A recent issue of Scientific American had a very good theory on how that occurs and why.\n\nIf I'm getting the gist of it right, they're not sure why clusters of stars occur in a semi-pinwheel pattern, since based on observed mass there simply isn't enough to cause such a structure to form or remain stable.  The theory in SciAm had something to do with a coincidence of travelling wave patterns rather than any deep dark mysteries of physics, filiments, or anything else.\n\nSee http://www.sciam.com/, October 2005 issue, p. 43, "Ripples in a Galactic Pond." Very nice article and they explained it more clearly than anything I could put together.
26002
If the sun were part of a binary system, it would revolve around the barycenter of the binary system. We would be able to dected this movment by comparing the Sun's position to other nearby stars and to more distant stars. Since we don't dectect any such movement around the barycenter, that means that any such compainion star must be very very small, making the barycenter close to the sun's positon, or very far away, making the motion of the sun about the barycenter very slow. \n\nNeither of these conditions are true of any other binary star system we see, so no.
368482
sounds like it could have been sirius, in the constellation canis major. this is the brightest star in the northern hemisphere.
205073
the doppler effect means that if an object is moving away from us the light it is sending out is slightly more red than normal (the wave length is longer)-a red shift, if it is moving towards us the light from it is slightly more blue(wavelength is shorter)- a blue shift. Most of the galaxies we see in space are red shifted so everything is moving away from everything else. This proves that so far the universe is expanding. If gravity gets the better of us and all the galaxies begin to move in on each other then they would be blue shifted. This may well happen in the far off future- we can't tell yet, but Even if this was happening they wouldn't all meet in a 'big crunch' (the opposite of the big bang) for a few billion years so it's not really anything to worry about!
16380
Yes.\n\nAlthough not very much.\n\nThis technique is one of those used by us to detect planets in other solar systems. (Although these are a heck of a lot closer than the Adromeda Galaxy.) The offical name for this method is "astrometric detection."\n\nThe largest wobbles we can see occur when there is a relatively large planet very close to the star. Planets such as these are called "hot jupiters." \n\nFor someone else to detect a wobble from us they would need better instruments. Most of the wobble from the sun would come from Jupiter - its effect dwarfs that of all the other planets combined. But since Jupiter is, relatively speaking, far away from the Sun the extent of the wobbling is small.\n\nDetails on planets found thus far around other stars, using a variety of techniques, are included in these links. Note: the Extrasolar Planet Encyclopedia is an official resource for actual astronomers.