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6

As HDE 226868 noted in his answer, the Sun is not going to go supernova. That's something only large stars experience at the end of their main sequence life. Our Sun is a dwarf star. It's not big enough to do that. It will instead expand to be a red giant when it burns out the hydrogen at the very core of the Sun. It will continue burning hydrogen as a red ...


6

Here is the very study you are looking for by Bailer-Jones (2014). Using the re-reduction of the Hipparcos astrometry, he has integrated orbits for 50,000 stars to look for objects that might come or might have come close to the Sun. The K-dwarf Hip 85605 is the winner on that timescale, with a "90% probability of coming between 0.04 and 0.20pc between ...


4

Is there any resource that provides these current values? Yes. The JPL HORIZONS on-line solar system data and ephemeris computation service provides these values, and much more.


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According to wikipedia and other sources, a planet and a star always move in a circular orbit around the common center of mass of the both bodies ... This is not true. In the absence of other gravitational sources, a planet and a star move in elliptical orbits about the common center of mass. Ancient scientists assumed circular orbits, but only because ...


3

I thought I'd contribute an answer because there's a very recent paper on the subject: Measuring the solar radius from space during the 2012 Venus Transit It appeared in my RSS feeds this morning! A related writeup is online at the HMI website. To answer the question, this measurement uses the transit of Venus to fit the limb-darkening law of the Sun. ...


2

Tracy Cramer is correct. Early in the life of the universe it is thought that star formation in "metal-free" gas favoured larger stars. These had short lives and very quickly enriched the interstellar and intergalactic medium with nucleosynthesis products. In fact the enrichment of the interstellar medium (ISM) in our own Galaxy is thought to have mainly ...


1

Solar flares are observed at wavelengths right across the electromagnetic spectrum, not just H alpha. The basic model for a solar flare starts with the magnetic field in the corona. You can think of the topology of the magnetic field to consist of loops that poke up out of the photosphere and extend into the corona. However, the photosphere of the Sun is ...


1

In the transition from a higher electron energy level to a lower one, say $m\mapsto n$, a hydrogen atom emits a photon of wavelength $\lambda$ satisfying $$\frac{1}{\lambda} = R_\infty\left[\frac{1}{n^2}-\frac{1}{m^2}\right]\text{,}$$ where $R_\infty = 1.09737315685\,\mathrm{m}^{-1}$ is the Rydberg constant. For $n=1$, i.e. the destination energy level is ...


1

I would go to the Arctic circle, where you can experience an almost perpetual sunset, without having to drive around. Edited to answer the question: My interpretation of the diagram, is: The terminator at a certain time near sunset, is the one shown towards the east (darkness approaches), running NE/SW. As time progresses, it moves into the top horizontal ...


1

Whenever I see this question discussed, it seems that the heliopause, or some variation thereof, is given as an answer -- and then it's mentioned that the Oort Cloud extends beyond it. A more correct answer, therefore, should be that it ends at that distance at which objects are, for all practical purposes, no longer bound to the solar system barycenter. ...



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