1 / 16

Understanding Stars

Understanding Stars. Our Sun. Our Sun. What is the structure of our sun? What makes the sun shine? How do we know? What tools do we use to study our nearest star?. What tools do we use?. Refracting telescopes- light passes through a lens to the eye

barney
Télécharger la présentation

Understanding Stars

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Understanding Stars Our Sun

  2. Our Sun • What is the structure of our sun? • What makes the sun shine? • How do we know? • What tools do we use to study our nearest star?

  3. What tools do we use? • Refracting telescopes- light passes through a lens to the eye • Good clarity, good power, good magnification, • High quality lenses needed, chromatic aberration • Reflecting telescopes- uses a mirror to focus light • Good clarity, good power, good magnification, glass not as high quality • Secondary mirror blocks some light • Radio Telescopes-focus incoming radio waves on an antenna, can be arranged in arrays • X-Ray telescopes- detect incoming X-rays, space telescopes, focus on learning about black holes • Gamma Ray telescopes - space telescopes to study visible light and gamma rays. • And others. . .

  4. How do we know? • Spectroscopy - the study of the properties of light • Detailed study of this in physics • Depends on the wavelength • Think a rainbow = continuous spectrum

  5. How do we know? • Absorption spectrum - when light is passed through cool gas under low pressure the gas will absorb some light and leave dark bands on the spectrum.

  6. How do we know? • Emission Spectrum - when light is passed through HOT gas under low pressure the gas will emit some light and these appear as bright bands on a dark spectrum. These act as finger prints to stars and tell us the chemical composition of stars.

  7. Structure of the Sun • Photosphere = visible surface • Interior • Atmospheric layers (2) • Chromosphere • Corona

  8. Photosphere • Visible surface of the sun • Appears to have a grainy texture. • Called granules • size of TX • last 10-20 min • Due to convection within the sun • Composed of 90% hydrogen, and <10% helium.

  9. Sunspots • Dark areas on surface (photosphere) • Dark due to lower temperature • Show sun activity and rotation of sun • More spots = higher solar activity, 11 year cycle

  10. Chromosphere • Layer of atmosphere, thin (few thousand km) • Visible during an eclipse • Magnetic field evidence of the sun present in this layer.

  11. Prominences • Arches or loops of chromospheric gases • Extend into corona • Ionized gases that are trapped by magnetic fields. • Show areas of intense activity

  12. Corona • Outermost portion of solar atmosphere • Origin of solar wind, aka space weather • Energy travels at speeds up to 800km/sec. • Solar flares

  13. Solar Flares • Explosive solar events • Release enormous amounts of energy in form of UV, radio, and X-rays • Cause an increase in intensity of solar wind due to atomic particles that are ejected

  14. NASA SDO example • SDO = Solar Dynamics Observatory • M5.6 class solar flare (Almost X class) • 7/2/2012

  15. Why does the sun shine? • Nuclear fusion (opposite of fission) in the interior or core. • Stars use nuclear fusion to combine light/low mass elements into heavier/higher mass elements. • Matter is converted to energy • 4 hydrogen combine to form one helium. • One proton in each hydrogen atom, atomic mass = 4.032 atomic mass units • One helium atom, atomic mass = 4.003 atomic mass units

  16. Why does the sun shine? • Stars use nuclear fusion to combine light/low mass elements into heavier/higher mass elements. • Results in a small loss of mass as the mass is converted into energy • Difference in atomic masses = 0.029 atomic mass units. • Energy! E = mc2

More Related