Review of Midterm HR Diagram Concept compare two

HR Diagram Concept compare two attributes humans … height and weight Inventors Hertzsprung and

Temperatures Kelvin Scale temperature 0 Kelvin 3 K 50 K 273 K 288 K

Spectral Sequence Spectral Type strength of H lines … type A through type P

Spectral Features in Stars and BDs Class O Spectrum Color Temp (K) H weak

Spectral Type Game Star Sun Sirius Proxima Procyon Kapteyn’s Star Arcturus Betelgeuse Sirius B

Slides: 11

Download presentation

Review of Midterm

HR Diagram Concept compare two attributes humans … height and weight Inventors Hertzsprung and Russell (working independently) around 1910 method for organizing stars Stars compare two attributes LUMINOSITY and TEMPERATURE or ABSOLUTE MAG and SPECTRAL TYPE (or COLOR) NEED DISTANCE !!!

Bright Stars Nearby Stars

Temperatures Kelvin Scale temperature 0 Kelvin 3 K 50 K 273 K 288 K 310 K 373 K ~ 2000 K 2900 K 5800 K 10000 K ~ 50000 K 15 million K object wavelength / color motion stops Universe Pluto frozen H 2 O Earth you boiling H 2 O coolest M 9 stars cool stars Sun Vega, Sirius hottest O 3 stars Sun’s core (black) radio far infrared far infrared near infrared / near infrared yellow blue-white / ultraviolet gamma rays photometry/spectroscopy to get blackbody … wavelength … temp

Spectral Sequence Spectral Type strength of H lines … type A through type P then learned about atomic structure H line strengths depend on TEMPERATURE O…B…A…F…G…K…M hot medium cool

OBAFGKM

Spectral Features in Stars and BDs Class O Spectrum Color Temp (K) H weak He ionized/neutral blue 31500 -49000 B H strong He neutral blue-white 10000 -31500 A H strongest metals ionized white 7500 -10000 F H weak metals ionized yellow-white 6000 -7500 G H very weak metals ionized/neutral yellow 5300 -6000 K H barely seen metals neutral orange 3800 -5300 M H ~ gone molecules red 2100 -3800 L H gone metal hydrides/alkalis magenta? 1200 -2100 T methane bands infrared? < 1200 Jupiter H 2, H 2 O, NH 3, CH 4 dark 124

Spectral Sequence Spectral Type strength of H lines … type A through type P then learned about atomic structure H line strengths depend on TEMPERATURE O…B…A…F…G…K…M hot medium cool Subtype need finer divisions 0 through 9 Luminosity but wait ! … not all stars of a given color are the same Class I supergiant 100 -1000 Rsun II bright giant III giant 10 -100 Rsun IV subgiant dwarf 0. 1 -10 Rsun NORMAL STARS V VI subdwarf

Sun Among Stars

Spectral Type Game Star Sun Sirius Proxima Procyon Kapteyn’s Star Arcturus Betelgeuse Sirius B Spectral Type G 2 V A 1 V M 5. 0 V F 5 IV-V M 0. 5 VI K 1. 5 III M 2 I DA 2