The milky way a classic spiral galaxy
Download
1 / 45

The Milky Way – A Classic Spiral Galaxy - PowerPoint PPT Presentation


  • 90 Views
  • Uploaded on

The Milky Way – A Classic Spiral Galaxy. Here’s the mystery story we’ll unfold… Fuzzy blobs in the sky – new solar systems, or “galaxies”? Observational tests Herschel’s map of the “universe” (Galaxy!) Dust, globular clusters, and the discovery of the Milky Way as our Galaxy

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about ' The Milky Way – A Classic Spiral Galaxy' - inari


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.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
The milky way a classic spiral galaxy
The Milky Way – A Classic Spiral Galaxy

Here’s the mystery story we’ll unfold…

  • Fuzzy blobs in the sky – new solar systems, or “galaxies”?

  • Observational tests

  • Herschel’s map of the “universe” (Galaxy!)

  • Dust, globular clusters, and the discovery of the Milky Way as our Galaxy

  • Structural components of our galaxy



Fuzzy blobs what were they
FuzzyBlobs – what were they?

  • Ever since the 1700’s, telescopes had shown these faint, oblong fuzzy blobs with central concentrations

  • 1. Nearby solar systems in formation, with a sun at the center??

  • 2. Or, giant pancake systems of stars (Galaxies – greek for “milk”)??



Henrietta leavitt harvard observatory in capetown
Henrietta Leavitt – Harvard Observatory in Capetown

  • She studied the Large Magellanic Cloud – what looked like a super star cluster of millions or billions of stars

  • Found stars with the right color and light curves to be classified as Cepheids

  • Like, Delta Cephei, Eta Aquilae, and other well known nearby examples

  • But here, she found an interesting pattern…



This makes cepheids excellent distance indicators
This Makes Cepheids Excellent Distance Indicators!

  • Take a bunch of photos and measure the brightness, construct the light curve

  • Measure the period of pulsation

  • Pick off the Luminosity from the Cepheid P-L Relation

  • Calculate how far away the star must be to have that luminosity look like the apparent brightness we see here from Earth


Discovery of the milky way as a galaxy
Discovery of the Milky Way as a Galaxy…

  • Edwin Hubble used the new 100” Mt. Wilson telescope in the 1920’s to image The Andromeda Nebula

  • Could see the brightest individual stars. Among them, variables of the right color and light variation to show them as Cepheids

  • Therefore, this was not a nearby nebula around a new star, it was an entire galaxy.

  • Herschel’s map then could be seen as a map of our own Milky Way Galaxy




But where are we in this huge star system
But… where are WE in this huge star system?

  • Globular Clusters are the clue

  • So first… what ARE globular clusters (globulars, as we say in the business)

  • Tight spherical cluster of a hundred thousand to a million stars, like this one…









  • Hubble found globulars in Andromeda; they were roughly spherically distributed, and centered on the center of the galaxy.

  • In our own sky, we’d known for over a hundred years that globulars are strongly concentrated in the summer sky; hardly any in the winter sky. Ergo - We must be far from the center!


Sun s orbit
Sun’s orbit spherically distributed, and centered on the center of the galaxy.


How old is the milky way
How old is the Milky Way? spherically distributed, and centered on the center of the galaxy.

  • Globular clusters again are the clue…

  • As we saw, we can age date any star cluster…

  • The main sequence is a mass sequence; higher mass stars live shorter lives.

  • We use stellar evolution models and take advantage of the fact that all stars in a cluster are born at the same time

  • The turnoff point tells you the age of the cluster


Glob cl hr diagram age of mw
Glob Cl HR diagram – age of MW spherically distributed, and centered on the center of the galaxy.


Sun in mw edge on
Sun in mw edge on spherically distributed, and centered on the center of the galaxy.


Solar neighborhood 25 nearest stars
Solar neighborhood; 25 nearest stars spherically distributed, and centered on the center of the galaxy.


Solar bubble
Solar bubble spherically distributed, and centered on the center of the galaxy.


Solar neighborhood spiral arm
Solar neighborhood spiral arm spherically distributed, and centered on the center of the galaxy.


Rho ophiuchi
Rho ophiuchi spherically distributed, and centered on the center of the galaxy.


Mw arms near us orange
MW arms near us orange spherically distributed, and centered on the center of the galaxy.


Shock wave spiral arm
Shock wave spiral arm spherically distributed, and centered on the center of the galaxy.


Canis major stream
Canis Major stream spherically distributed, and centered on the center of the galaxy.


Infalling mw gas
Infalling MW gas spherically distributed, and centered on the center of the galaxy.


Let s take a trip to the center of the milky way galaxy
Let’s take a trip to the center of the Milky Way Galaxy… spherically distributed, and centered on the center of the galaxy.

  • We’ll have to use pictures taken at long wavelengths, which can penetrate through the vast amounts of dust between here and there… Infrared, and radio wavelengths


Sagittarius mw above kofa mtns
Sagittarius MW above Kofa Mtns spherically distributed, and centered on the center of the galaxy.


2mass mw stars only
2MASS MW stars only spherically distributed, and centered on the center of the galaxy.


2mass mw allsky incl lmc smc
2MASS MW; allsky incl LMC,SMC spherically distributed, and centered on the center of the galaxy.


2mass milky way nucleus shows
2MASS Milky Way; nucleus shows spherically distributed, and centered on the center of the galaxy.


Mw core sequence wide field
MW core sequence; wide field spherically distributed, and centered on the center of the galaxy.


Mw core 2
MW core 2 spherically distributed, and centered on the center of the galaxy.


Mw core 3
MW core 3 spherically distributed, and centered on the center of the galaxy.


Mw core 4
MW core 4 spherically distributed, and centered on the center of the galaxy.


Mw core 5
MW core 5 spherically distributed, and centered on the center of the galaxy.


Mw core 6
MW core 6 spherically distributed, and centered on the center of the galaxy.


Mw core
MW core spherically distributed, and centered on the center of the galaxy.


Mw core 7
MW core 7 spherically distributed, and centered on the center of the galaxy.


Summary
Summary spherically distributed, and centered on the center of the galaxy.

  • Pop I,II show MW formed spheroid first, then disk more gradually.

  • Star formation in disk right through today

  • Giant black hole in nucleus of Galaxy


ad