1 / 32

Stellar Measurements and Properties

Stellar Measurements and Properties. How many stars can you see on a given night?. 8,741 visible stars. But we don’t see half, due to our Hemispheric sight. 8,741/2 = 4,370 But that is the entire count and we only see half at any given time on earth. 4,370/ 2 = 2,185

donaldrusso
Download Presentation

Stellar Measurements and Properties

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. Stellar Measurements and Properties

  2. How many stars can you see on a given night? • 8,741 visible stars. • But we don’t see half, due to our Hemispheric sight. 8,741/2 = 4,370 • But that is the entire count and we only see half at any given time on earth. • 4,370/ 2 = 2,185 • Not yet…also limited by our technological advancements. • Answer about 1,500 – 2,000 depending on your limiting factors

  3. Limiting factors

  4. Absolute vs. Apparent magnitude • apparent magnitude of a celestial body is a measure of its brightness as seen by an observer on Earth. The brighter the object appears, the lower the value of its magnitude. • absolute magnitude measures a celestial object's true brightness from a set distance.

  5. Luminosity Luminosity - a measure of the total amount of energy radiated by a star or other celestial object per second. This is the power output of a star.

  6. Star Magnitude How Much Brighterthan a Sixth Magnitude Star Logarithmic scale of2.512 X between magnitude levels Starting at Sixth Magnitude 1 100 Times 2.51 x 2.51 x 2.51 x 2.51 x 2.51 2 39.8 Times 2.51 x 2.51 x 2.51 x 2.51 3 15.8 Times 2.51 x 2.51 x 2.51 4 6.3 Times 2.51 x 2.51 5 2.51 Times 2.51 x 6 Six Star Magnitude Table

  7. Photon: The smallest (quantum) unit of light/electromagnetic energy. Photons are regarded as particles with zero mass and no electric charge.

  8. Eclipsing Binary: Rare binary-star system that is aligned in such a way that from Earth we periodically observe one star pass in front of the other, eclipsing the other star

  9. Cepheid Variable • A Cepheid is usually a giant yellow star, pulsing regularly by expanding and contracting, resulting in a regular oscillation of its luminosity. • This type of star is helpful in determining distances. A.k.a: stellar “Ruler”

  10. Parallax • Astronomers can measure parallax by measuring the position of a nearby star with respect to more distant stars behind it. • Then measuring those distances again six months later when the Earth is on the opposite side of its orbit.

  11. D= 1 / P (where p= arc sec)

  12. Sample Stellar calculations • Star A has a parallax angle of 0.742 arcsec. • Star B has a parallax angle of 0.5 arcsec. • Which star is further? • How much further?

  13. Bright, Brighter, Brightest • Castor = 1.16 • Pollux = 1.58 • Which star is brighter? • How much brighter?

More Related