ASTR 1102 002 2008 Fall Semester Joel E Tohline Alumni Professor Office 247 Nicholson Hall Slides from Lecture02 Course Syllabus corrected Final Exam time Evaluation of Coursework Corrected final exam time Chapter 17 The Nature of Stars Describe Population of stars Location Coordinate position Distance Motion Across the photo sky Toward away from us Intrinsic properties Mass Color Brightness Age Describe Population of fans Location Coordinate position Distance Motion Across the photo sky Toward away from us Intrinsic properties Mass weight Color clothes Brightness Age Location Determine exact location of every fan Coordinate position Distance Location Determine exact location of every fan Coordinate position x y coordinate on photo Distance distance from photographic lens Location Determine exact location of every fan Coordinate position x y coordinate on photo Distance distance from photographic lens straightforward Location Determine exact location of every fan Coordinate position x y coordinate on photo Distance distance from photographic lens not so straightforward Location or using GPS system Coordinate position latitude longitude Distance altitude above sea level e g Google Earth Google Earth Location Determine exact location of every star Coordinate position Distance Location Determine exact location of every star Coordinate position declination right ascension Distance from Earth Straightforward Analogous to latitude longitude e g Google Sky Location Determine exact location of every star Coordinate position declination right ascension Distance from Earth Textbook Box 2 1 pp 30 31 Google Sky Location Determine exact location of every star Coordinate position declination right ascension Distance from Earth not so straightforward Determining Distances to Astronomical Objects Not at all straightforward Only direct method is Stellar Parallax See textbook discussion associated with Figs 17 1 and 17 2 Other indirect methods will be discussed later Parallax Stellar Parallax Individual Stars Location in Space Coordinate angular position on the sky Distance from Earth Motion through Space Motion across the sky proper motion Motion toward away from us radial velocity Intrinsic properties Brightness luminosity magnitude Color surface temperature Mass Age Individual Stars Location in Space Coordinate angular position on the sky Distance from Earth Motion through Space Motion across the sky proper motion Motion toward away from us radial velocity Intrinsic properties Brightness luminosity magnitude Color surface temperature Mass Age Location Coordinate position Distance Motion Across the photo sky Toward away from us Location Coordinate position Distance Motion Across the photo sky Toward away from us Location Coordinate position Distance Motion Across the photo sky Toward away from us Which object in this photo is moving Motion Across the Sky proper motion http www psi edu esquerdo jim astfov gif Location Coordinate position Distance Motion Across the photo sky Toward away from us Determining Motion of Astronomical Objects toward away Surprisingly straightforward Doppler effect See textbook discussion in Chapter 5 5 9 Doppler Effect 5 9 The measured frequency wavelength of light changes if the light source is moving toward or away from you Light is blue shifted if the object is moving toward you Light is red shifted if the object is moving away from you Direct analogy with the behavior of sound waves Individual Stars Location in Space Coordinate angular position on the sky Distance from Earth Motion through Space Motion across the sky proper motion Motion toward away from us radial velocity Intrinsic properties Brightness luminosity magnitude Color surface temperature Mass Age Prominent and Obscured Objects Prominent and Obscured Objects NOTE Transient Events in time also occur NOTE Transient Events in time also occur NOTE Transient Events in time also occur NOTE Transient Events in time also occur NOTE Transient Events in time also occur Individual Stars Location in Space Coordinate angular position on the sky Distance from Earth Motion through Space Motion across the sky proper motion Motion toward away from us radial velocity Intrinsic properties Brightness luminosity magnitude Color surface temperature Mass Age