Astr 601Astr 601(Astrophysics course)(Astrophysics course)

Galactic Structure & Cluster of stars & Galactic Structure & Cluster of stars & Interstellar medium Interstellar medium

Number of hours (Th. 2h + Pr. 1h = Cr. 3h)

Dr. Alaa Eldin Fouad Mohamed AliDr. Alaa Eldin Fouad Mohamed AliKing Abd Aziz University, Faculty of Science,

Department of Astronomy.Second semester 2007/2008

What's the difference between astronomy and astrophysics?

Technically speaking, astronomy is the science of measuring the positions and characteristics of heavenly bodies, and astrophysics is the application of physics to understand astronomy. However, nowadays, the two terms are more or less interchangeable since all astronomers use physics to understand their findings

Traditionally astronomy has been more observational in scope while astrophysics is more analytical. Thus astronomers look through telescope while astrophysicists model data. The distinctions are much more blurred now and most astronomers/astrophysicists do both.

Course objectives, description and Philosophy:

The aim of this course, in brief, is to provide a broad introduction to the Milky Way galaxy, types of star clusters and interstellar medium. The specific major topics to be covered in this course are (a) Galactic structure and dynamics. (b) Cluster of stars . And (c) Interstellar gas and dust .

Astrophysics is the branch of astronomy concerned with the physical processes associated with the celestial bodies and the intervening regions of space. It deals principally with the energy of stellar systems and the relation between this energy and the evolution of the system.

Students should keep in mind that the course is the lectures - we will not follow the book directly, and the book is not a substitute for lecture attendance, which is simply expected of you.

Textbooks:1- Introductory Astronomy and AstrophysicsIntroductory Astronomy and Astrophysics, M. Zeilik and S.A. Gregory, Saunders College Publishing (1998). 2- An introduction to Modern AstrophysicsAn introduction to Modern Astrophysics, Bradley W. Carroll & Dale A. Ostlie (1996) Addison-Wesley Publishing Company, Inc.3- Astronomy: A physical PerspectiveAstronomy: A physical Perspective, Marc L. Kutner (2003), Cambridge University Press. 4- The Fullness of SpaceThe Fullness of Space , Gareth Wynn-Williams (1992) Cambridge University Press.

Examinations:The course grade will be determined on the basis of homework, midterm exam and final exam.

Grades:Grades will be based on homework problems & take home exam (30%), lab experiments (25%), midterm exam (20%) and final exam (25%).

Course syllabus:Lecture 1: The Milky WayThe structure of our galaxy (Disk, Bulge, Halo), Historical introduction (Herschel’s Galaxy, Kapteyn’s Galaxy, Shapley and center of the Galaxy, Dust clouds in the galaxy, Work of Trumpler on IS dust absorption, Rotation of the Galaxy, Galactic spiral arms, 21-cm radiation, HII regions, IS molecules) ⇒ Ch 14.1Lecture 2: The Milky Way compositionConstituents of the Galaxy (stars, IS gas, dust particles, cosmic rays, dark matter), Galactic coordinates ⇒ Ch 20 → Ch 22.2Lecture 3: Stellar populationStellar population (Pop I, Pop II, Pop III),⇒ Ch 13.C, Ch 14.3, Ch 20.2, Table 20.1Lecture 4: Stellar clustersOpen clusters (distribution, H-R diagram, photometric distance, ages)⇒ Ch 13.3C, Ch 14.2B, Ch 14.3, Ch 16.4 → Ch 22.2Lecture 5: Moving clusters ⇒ Ch 19.3Lecture 6: Globular clusterGlobular clusters (distribution, H-R diagram, photometric distance, ages)⇒Ch 14.2, Ch 14.3, Ch 16.4, Ch 19.3 → Ch 22.3Lecture 7: Galactic rotationGalactic Rotation (rotation from HI and CO clouds, curve for the Galaxy, the nature of dark matter), Galactic rotation (rotation parameters, mass model of the galaxy)⇒ Ch 14.4, Ch 16.2, Ch 16.3, Ch 19.4, Ch 20.1 → Ch 22.3

Lecture 8: Spiral structureSpiral structure (optical map of spiral structure, radio map of spiral structure, HII, OB associations and GMCs rotation tracers, the evolution of spiral structure, density wave model)⇒ Ch 20.2A, Ch 20.3Lecture 9: Galactic nucleus and Galactic bulgeGalactic nucleus and central bulge (If observation, radio observation, X‐ray observation, nature of the galactic nucleus)⇒ Ch 20.1C, Ch 20.2C → Ch 22.4Lecture 10: Interstellar gasInterstellar medium (Brief history, components of ISM), IS gas (Types, HII regions, HI clouds, dense molecular clouds, IS masers)⇒ Ch 15.2, Ch 20.1B, Ch 20.2 → Ch 12.1Lecture 11: Interstellar dustInterstellar dust (Dark nebulae and extinction,  IS polarization, reflection nebulae, the nature of  IS    grains)⇒ Ch 15.1 → Ch 12.1Lecture 12: Galactic cosmic rays and galactic magnetic field⇒ Ch 15.3, Ch 20.4 (A&B&C)Lecture 13: Evolution of the Galaxy* ⇒ Introductory astronomy and astrophysics (Zeilik & Gregory 1988)** → An introduction to modern astrophysics (Carroll & Ostlie 1996)

OverviewOverview

The center of the distribution of globular clusters shows the location of the Milky

Way’s center.• globular clusters• galactic nucleus• nuclear bulge• spiral arms• disk• note position of the

Sun, just over half way out.

This classification scheme is known as the Hubble Tuning Fork Scheme

Galaxies seem to take one of four different appearances

ELLIPTICALSType E0 Type E3 Type E7

Galaxies seem to take one of four different appearances

SPIRALS

The Milky Way is only one among billions of galaxies

The Swan Nebula (M17): Emission Nebula

Continuum Phenomena:Reflection and Dark Nebulae

• Dust scatters incident light• Not a line process, scatters

continuum

reflection

dark

dark

QSO Spectrum with IGM Absorption

http://apod.gsfc.nasa.gov/apod/image/9903/ngc1435_kitahara_big.jpg

http://apod.gsfc.nasa.gov/apod/image/0102/mz3_hst_big.jpg