What is Stellar: Definition and 169 Discussions

A stellar collision is the coming together of two stars caused by stellar dynamics within a star cluster, or by the orbital decay of a binary star due to stellar mass loss or gravitational radiation, or by other mechanisms not yet well understood.
Astronomers predict that events of this type occur in the globular clusters of our galaxy about once every 10,000 years. On 2 September 2008 scientists first observed a stellar merger in Scorpius (named V1309 Scorpii), though it was not known to be the result of a stellar merger at the time.Any stars in the universe can collide, whether they are 'alive', meaning fusion is still active in the star, or 'dead', with fusion no longer taking place. White dwarf stars, neutron stars, black holes, main sequence stars, giant stars, and supergiants are very different in type, mass, temperature, and radius, and so react differently.A gravitational wave event that occurred on 25 August 2017, GW170817, was reported on 16 October 2017 to be associated with the merger of two neutron stars in a distant galaxy, the first such merger to be observed via gravitational radiation.

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  1. A

    R136a defies Laws of Stellar Evolution

    At 265 SM, and age 1.7 Million years, at 163,000 Light Years Away in the R136 cluster, is R136a. But, it shouldn't be alive now. It should have exploded given the model of Solar Mass Evolution at 200,000-375,000 Years old of age. It's in it's Wolf-Rayet phrase, but it still shouldn't be alive...
  2. Ravyan Asro

    Pros and cons for a career in stellar astronomy

    I am really interested in learning more about the space and the universe. And studying about stars interests me the most. So, I have decided for a career in stellar astronomy. However, stellar astronomy is a very huge field of space science and a rarely chosen career. I have a thousand of...
  3. Chronos

    Notes on Star Formation: A Primer for Stellar Formation

    Here; http://arxiv.org/abs/1511.03457, Notes on Star Formation, is a primer for those with an unnatural desire for a graduate level textbook discussion of stellar formation. Fair warning, it is not for the math challenged.
  4. D

    Calculating Planet Mass from Stellar and Orbital Speed

    Homework Statement Stellar mass 3.8 x 10^30 kg Star's orbital speed: 90 m/s Planet's orbital speed: 95,000 m/s Whats the mass of the planet in kilograms [/B]Homework EquationsThe Attempt at a Solution
  5. J

    Luminosity & Stellar Lifetimes

    Homework Statement Quasars have a luminosity on the order of 10^12 times more than our Sun. Our Sun is expected to last 5 billion years. Using this number estimate (in seconds) how long our Sun would last if it started using energy at the rate of a Quasar. Homework Equations None The Attempt...
  6. vmr101

    Solve these equations numerically - Stellar Abundance Ratios

    1. Question from a textbook. I have written down the differential equations for part a) and shown part b), but I am unsure of how to tackle part c). 2. This is the Question from the book http://www.m-rossi.com/img/asp3012-1.png Any advice would be grateful. Thank you
  7. jk1956

    Stellar aberration measurement

    Hi everyone, I am interested in measuring stellar aberration as a challenge to myself; I am more of a physicist than an astronomer. I have a fair knowledge of telescopes and imaging. I would appreciate if somebody can give me instructions or point to some references on: which star to select...
  8. H

    Transformation equation of velocity contradicts stellar aberration?

    Let S be the frame where the Sun is at rest. Imagine light from the North Star reaches the centre of the Sun, and let's define the equatorial plane as the plane that is perpendicular to this light and cuts the Sun into two hemisphere. Suppose a distant star A is on this equatorial plane and its...
  9. excelsior

    Reading Recommendation - Sun / Stellar Evolution

    My apologies for starting a thread on a seemingly easy and searchable topic. But, alas, I've searched here, Amazon, google, Goodreads etc and wanted to get some recommendations. Specifically book suggestions on The Sun and / or Stellar evolution. I've ran across several intriguing textbooks...
  10. C

    MHB Integral calculus: stellar stereography

    Hi there, I have a question I'm stuck on. It is: Astronomers use a technique called stellar stereography to determine the density of stars in a star cluster from the observed (two-dimensional) density that can be analysed from a photograph. Suppose that in a spherical cluster of radius R the...
  11. EpicAll Rounder

    What is Stellar Flux and How Does it Affect Solar Wind?

    I have a little problem about Stellar Flux. I've searched google and bing for info but to no avail. Please help me understand Stellar Flux. Thanks, Epicall Rounder
  12. avito009

    Why is stellar ash found in the core of a White Dwarf so dense?

    A normal star's core consists of Hydrogen but a white dwarf is itself the core and it consists of stellar ash. So the degeneracy pressure is exerted when this stellar ash becomes very dense (In other words when the white dwarf becomes very dense). Am I right? The density of a white dwarf is so...
  13. avito009

    What prevents a star from collapsing after stellar death?

    When the star stops burning because heavier elements like Iron are formed in its core. Then the gas pressure stops and as you know the gas pressure helps keep a star in equilibrium because it provides pressure against the force of gravity. So Iron does not give off energy. So what stops the star...
  14. AotrsCommander

    How to estimate/calculate stellar wind from a star?

    How do you estimate/calculate how much solar wind a star produces? (Can we even make a passable attempt?) I'm trying to work out whether a fictional exoplanet in orbit around R Coronae Borealis would need a magnetic field (as there appears to now be some debate on a cursory google search on...
  15. L

    Plasmatic Ionization in Stellar Nucleosynthesis

    So, I'm not a student in physics. Or astronomy. I'm actually a med student, just fairly curious. In stellar nucleosynthesis, plasma is required to fuse the particles from my understanding. In trying to record all the various reactions (PP Chain, Triple α Process, CNO Cycle), but I can't find...
  16. N

    Exploring the Evolution of Stars: A Database of Stellar History

    Just been looking around for any good resources or databases which show history of stars in the universe. I have mostly been looking into the size and chemical content of them (like those of population I, II, III). But just looking for some real data and numbers to go with it, like star sizes...
  17. E

    I'm sorry, I'm not sure what your question is. Could you please clarify?

    In an inertial reference frame - and zero gravity field - we believe that any passing photons go in Euclidean straight lines. If I have some constant velocity towards the path of a passing photon, it still goes in a straight line, just at a different angle. But if I am accelerating towards that...
  18. J

    Find the mean number density of particles in the stellar atmosphere.

    Homework Statement The atmosphere of a star has a mean radiation pressure of 0.33 N m-2and a mean gas pressure of 8300 N m-2. Calculate: a) the mean number density of particles in the stellar atmosphere, and b) the radiation pressure in a stellar atmosphere with twice the effective...
  19. AotrsCommander

    How to calculate absolute magnitude of a stellar body?

    I'm trying to find the appropriate formula (and abstractions to plug into it as necessary) to work out the absolute magnitude (from which I can dervive an apparent magnitude) of a solar body. I've found a lot of formula which relative absolute and apparent magnitude, but trying to find how to...
  20. K

    Speculation on the nature of collapsed stellar cores

    Neutron stars formed from supernova events are prohibited from becoming black holes because it is thought that the gravitational force is not enough to overcome Fermi degeneracy of the neutrons or quark gluon soup at the core of these objects, however, addition of more mass can overcome this...
  21. E

    How is it possible for binary stars to not show changes in aberration angles?

    I thought I understood how stellar aberration conformed to Special Relativity. The CHANGE in that angle comes from the CHANGE in our orbital velocity direction about the sun over six months. And it is the same for all stars. That is fine if there are no significant changes in a star’s state of...
  22. C

    MATLAB Stellar structure equations in Matlab?

    Does anyone have a Matlab file for solving the stellar structure equations that they wouldn't mind passing along? I'm trying to settle an argument with a friend that they can't really be used to describe nuetron stars and I don't have much programming experience. Thanks, Alex
  23. F

    Stellar structure of stars problem

    Homework Statement Consider a star of radius R, with density p that is constant, composed of classical, nonrelativistic, idealg gas of fully ionized hydrogen. a. Solve the equations of stellar structure for the pressure profile, P(r) with the boundary condition P(R)=0 b. Find the temperature...
  24. ckirmser

    Stellar Classification Limits: Temperature & Magnitude

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  25. M

    Experimental status of stellar structure

    A naive question from someone who knows nothing about the subject: I was wondering how much we can tell experimentally about what's going on inside a star. Can we determine, say, how the temperature or pressure vary as a function of the radius? Thanks in advance.
  26. DHF

    Can a Nuclear Device Ignite Jupiter's Atmosphere?

    A friend of mine is writing a Sci Fi tale set a few centuries in the future. While there will be futuristic technologies to make the plot go, she said she wants to try to make it realistic at least to the point where she inst violating the laws of physics. The part she asked me about involved...
  27. J

    Stellar or Solar system Astronomy?

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  28. shounakbhatta

    Conservation of mass - Stellar equation

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  29. J

    What can stellar kinematics tell us about the IMF?

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  30. T

    Stellar formation / Expansion / Education questions

    Regarding the creation of the universe and the current model: Is it assumed that the universe, at the time of creation was finite in size (or at least more finite than it is now) prior to the rapid expansion, or was the protoexistance finite in size in an infinite universe? So, did the...
  31. N

    What's the role of stellar interference in redshifts?

    So if there are as many galaxies in the Universe as is claimed what's the role of interstellar combination of light waves on the view of the sky we get here on Earth?
  32. S

    VPython project involving black-hole and stellar object.

    Homework Statement My partner and I are doing a project for our introductory Honor's Physics course, in which we must use VPython to explore a theoretical concept in physics. We were able to choose whichever topic we wished, although it had to be approved, and it had to be theoretical. Our...
  33. P

    Stellar structure - Helium burning

    1. The problem statement. Calculate the energy generated per unit mass, if helium burning produces equal amounts (mass fractions) of carbon and oxygen. mH = 1.672621581 x 10^-27 kg 2. The attempt at a solution Helium burning produces carbon according to the following reaction: 3He -> C...
  34. M

    Stellar Nebulae and angular momentum

    Maybe this is a simple question but, all the stuff I've been reading so far keeps talking about protostars and their angular momentum being a consequence of the surrounding nebula. Why do they inherit that in the first place? Is is just a consequence of the gravitational collapse?
  35. L

    Calculating Stellar radius from bolometric flux

    Homework Statement The monochromatic flux emitted from unit surface area of a black body is given by F_{\lambda}(T) = \frac{2h\pi c^{2}}{\lambda^{5}} \frac{1}{exp(hc/\lambda KT)-1} Wm^{-2}m^{-1} If the distance to star X is 620 parsecs, calculate: (a) the radius of star X, in...
  36. B

    On the Origin of Solar and Stellar Magnetic Fields

    On the Origin of Solar and Stellar Magnetic Fields There is recent evidence that the solar magnetic cycle has been interrupted. This is a link to Livingston and Penn’s paper that notes the magnetic field strength of newly formed sunspots is decreasingly linearly. Specifically, why the...
  37. E

    How are stellar EM radiation formed?

    How are stellar EM radiation formed?? I've read this in many books and sites... Any object above 0 K will emit EM radiation of all wavelengths... Now this is confusing me a lot... I mean, how for example a sun emit wavelength s of a Radio and it is the same sun which emits ultra violet and...
  38. A

    Stellar Nucleosynthesis - What makes it fascinating?

    I've just completed a research assignment on Stellar Nucleosynthesis, and I feel it needs something that will make it stand out. Our class were given the job of researching and investigating a topic that is related to Nuclear Power/Energy/Physics. To obtain top marks, it's essential that...
  39. E

    The stellar evolution. Low Mass stars

    Well, this topic is driving me crazy so any answers or replies should preferably be detailed and in an easy way.. My question is i want a sum up of the evolution of a low mass star... I will give my answer and tell me where are the dropouts.. Let me begin,With a protostar accreting hydrogen in...
  40. J

    What is the formula for calculating the lifetime of a star?

    Homework Statement I have to calculate the lifetime of a star that is 300,000 times as luminous as the sun and 24 solar masses. Homework Equations lifetime = k * m/l The Attempt at a Solution lifetime = 10^10 * (24/300000) lifetime = 800000 years I feel as if this is...
  41. T

    Understanding Stellar Lifespans: Comparing Luminosity & Mass

    Hi, all how would you go about finding out how much longer a star would live compared to another if you knew the one star was x times more luminous and y times more massive?
  42. Drakkith

    Metallicity and Stellar Formation

    What does metallicity have to do with stellar formation? Why does low metallicity in stars in the very early universe mean that they needed to be more massive than modern stars to form?
  43. J

    Convective motion and Stellar jitter

    Page 26 of http://www.maths.qmul.ac.uk/~rpn/ASTM735/Week7.pdf claims that stellar jitter can be caused by the convective motions in the stellar photosphere. Can someone explain that to me as I don't understand it?
  44. T

    Stellar aberation, a One way measurement of c?

    Why isn't Stellar aberation considered to be a one way measurement of c? if the angle of aberation (Theta) is 20.5 arcseconds and the Earth's orbital speed is 29.79 Kilometers/second normal to the arriving star light. The value of c should be: c= Vt/tan(Theta) = 29.79/9.94E-5 = 299737.98...
  45. R

    L-LOG-SUN - value on stellar data

    On the exoplanet database they have a value which I am not familiar with, can anyone help me understand what value they are displaying represents? Luminosity ? " compared to solar luminosity? Does LOG mean they performed a logarithm? see attached...
  46. L

    Stellar physics (number crunching)

    Decided to have a go at an extra credit assignment: Homework Statement I am given some data for ~9000 stars of 21 known spectral types along with their: measured parallax & uncertainty proper movements in right ascension & declination per year (B-V) color & relative mag (V). I am...
  47. R

    Where can I find a comprehensive online database for stellar data analysis?

    I am looking for a On line or downloadable stellar highly detailed database. Nasa had a excellent one but seemed to remove it from (NASA Star and Exoplanet Database (NStED). Wiki has lots of detail on there website but its star by star basis.I want to analyse large batches of stellar data...
  48. T

    Mediocre undergrad vs. stellar graduate GPA

    I have a mediocre (by my standards) GPA of 3.34 in the undergraduate math program. However, my graduate cumulative GPA in mathematics is very good at 3.96. I have one semester before I graduate with an MS in mathematics. I'm applying to Phd programs at Kent State University and Ohio State...
  49. C

    Stellar object ejects a jet Special Relativity

    Homework Statement A stellar object at some known large distance ejects a ‘jet’ at speed v towards an observer obliquely, making an angle θ with the line of sight. To the observer the jet appears to be ejected sideways at speed V . Prove V = c sin θ (c/v − cos θ )−1 , and show that this...
  50. R

    Using Rspec to Interpret Stellar Spectra

    Hello, PF. I'm a simple high school student who likes a challenge, and as such, I decided to put together a research project involving reading spectral lines from photographs I took. I got the lens, I got the camera, I got pictures, and now I'm stumped. Reading up on Rpsec, a lot of it's...
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