Phys 102 Astronomy EXAM 2: LIGHT AND STARS: GROUP

Transcription

1 Phys 102 Astronomy EXAM 2: LIGHT AND STARS: GROUP Name Key 1) 25 On the diagram below, a) show the constellation lines of Lyra, Cygnus, Aquila and Sagittarius, b) label the stars Vega, Sheliak, Sulaphat, Deneb, Alberio, Sadr, Altair and Tarazed, c) show the positions of Lagoon, Eagle, Ring, and Veil Nebulas and Cyg. X-1, and state the stage of stellar evolution taking place in each. Deneb CYGNUS Sadr LYRA Vega Sulaphat Sheliak Alberio Cyg X-1 Black Hole Star Death Ring Nebula in Lyra Planetary Nebula: Star death Veil Nebula in Cygnus Supernova Remnant: Star death Tarazed Altair AQUILA Eagle Nebula in Scutum Star formation SAGITTARIUS Lagoonl Nebula in Sagittarius Star formation Starry Night image of the view from Canton, New York, USA, 4:00 pm, November 6

2 2) 8 On the HR diagram below, Label the axes (the horizontal axis is not linear but the order is standard). Circle and label the regions of the main sequence, red giants, red supergiants and white dwarfs Label these!! O B A F G K M Spectral Class EXTRA CREDIT FOR MNEMONIC FOR THE ORDER OF SPECTRAL CLASSES: LEARN THE PACE OF THE UNIVERSE WHICH IS EVER CONSTANT, AND SEEK NOT TO RACE AHEAD OR YET TO DRAG BEHIND. A NEW DAY HAS BEEN ADDED TO YOUR EXPERIENCE. IT IS NOT PAST NOR IS IT LOST, BUT IS NOW YOURS FOREVER. BEYOND THIS LOVELY NIGHT COMES ANOTHER MORNING, ANOTHER NOON, AND YET ANOTHER NIGHT. IT WILL ALWAYS BE SO. THEREFORE, SET YOUR STRIDE FOR ETERNITY; ABANDON YOUR WILL IN FAVOR OF THE UNIVERSAL ORDER OF THINGS; AND KNOW ONLY ONE DUTY: TO LOOK IN WONDERMENT AT THE ENDLESS UNFOLDMENT OF INFINITE CREATION SAM CAMPBELL Page 2

3 3) 20 Use the constants σ = 5.67 x 10-8 W/m 2 K 4, L SOL =3.827 x W, and R SOL = 6.96 x 10 8 m and the equations below to complete the table. TEMPERATURE FROM SPECTRAL TYPE Tmax Tmin T = T max (subclass) 10 LUMINOSITY FROM MAGNITUDES. MSol RADIUS FROM LUMINOSITY L star = 10 M 25. Star R Star = L Star 4 4πσ T FIELD GUIDE TO THE STARS AND PLANETS CALCULATED STAR V M V r STAR Spectral T L RSTAR RSTAR/RSol ly Type K Solar Lums Watts meters ratio Enif (ε Peg) K2 I , x Alnitak (ζ Ori) O9.5 I 27,750 13, x x Aldebaran (α Tau) M1.5 I 3,425 17, x x ) 4 EXPLAIN what these numbers mean about these stars. They tell us the temperatures of the outer surfaces, how much energy they are emitting in Watts and how big they are. We can learn all this about the stars without leaving the lab (except to go to the observatory!). 5) 6 The Ghost Particle What fraction of the neutrinos that John Bachall predicted from the sun were detected by Ray Davis? How did they respond to this? He detected about 1/3 of the predicted neutrinos. He carefully checked his technique and Bachall his numbers but were convinced they were correct. What fraction of the neutrinos was the Sudbury Neutrino Observatory in Ontario able to detect? Why was it different from Ray Davis detection? At SNO they were able to detect all three types of neutrinos (e -,μ, and τ), whereas Davis had only detected one type (e - ). SNO detected all predicted. What did the SNO detection teach us about neutrinos and their mass?? In order to change into other types, neutrinos must experience time and therefore, they have to have mass so they don t move at the speed of light. Page 3

4 6) 12 But look to the night skies. It is a forest: stars in all stages of growth. The narrator (Michael Dorn, Star Trek TNG's Worf) states in A Star is Born, one episode of the Solar Empire series of TLC. While showing images of the star-studded reaches of the Milky Way, the narrator continues Here are the solar seeds, shoots, saplings, and decayed wood. Together they tell the 10-billion-year life story of our sun. What is the life story of the sun as told in the stars? C ITE EXAMPLES by name and constellation of solar seeds, saplings, mature trees and decayed wood (3 types) that have been observed with the Hubble Space Telescope and other instruments. Seeds: Eagle Nebula in Scutum, Lagoon Nebula in Sagittarius, Orion Nebula. Stars are being formed inside dense clouds of gas and dust. Saplings: Star clusters like the Pleiades in Taurus and H & Χ Persei (the double cluster) where stars are still in their sibling groups, or stellar litters. Mature Trees: Main sequence stars like the sun, Vega, and Altair Decayed Wood: Planetary nebulae like the Ring in Lyra, supernova remnants like the Veil in Cygnus or the Crab in Taurus, and black holes like Cyg X-1. These are where stars have died and left their constituent matter mostly gas and stellar cores to be taken up by another star-forming region. 6) 8 The woman shown is Annie Jump Cannon analyzing stellar spectra at the Harvard College Observatory. Describe the contributions to astronomy of the women of the HCO, in particular, those of Williamina Fleming ( ), Antonia Maury ( ), Annie Jump Cannon( ), and Cecilia Payne-Gaposchkin ( ) in the field of stellar classification. Maury: First classified spectra by complexity from A to O Fleming: Rearranged spectra by temperature to OBAFGKM Cannon: Added subclasses and classified lots of stars (>300,000!!) Payne: Determined the temperatures associated with each spectral class. ALL of these women classified lots of stars and made a huge contribution to the advancement of astronomy and spectroscopy. Page 4

5 7) 2 The wheelchair guy whose book Homer wished he d read is a) Kip Thorne of Cal Tech. b) Steven Hawking of Cambridge University c) Sir Martin Rees, Astronomer Royal. 8) 2 SOHO is a) a neighborhood on the south end of Manhattan Island. b) an expression of boredom. c) the Solar and Heliospheric Observatory orbiting the sun. 9) 2 If you fell into a star-sized (100 solar mass or so) black hole, a) you would be crushed by gravity very early in your trip. b) you would be spagetified by gravity very early in your trip. c) you would be able to send information to the outside until you reached the singularity. 10) 12 For the image shown, a) name the object and explain where it can be found in the sky, b) describe the stage of stellar evolution it represents, c) what created its appearance and c) explain what is happening at the points indicated. -- Eagle Nebula in Scutum between Aql & Sag -- Star formation -- Gas clouds are collapsing under gravity to form stars. Some stars have already formed. A B A: The comet-looking object is an EGG where the wind from a star above & right of B has stripped the gas from around the forming star. B: The gas is evaporating off the cloud due to the wind from a hot star to the upper right. 11) 12 Same as 10 for the image shown, -- Crab Nebula in Taurus -- Star death stellar remnant -- A star blew up in a supernova explosion in The gas is still moving outward from that event. A A: The gas from the original star is still moving away due to the explosion. B: The core of the original star has shrunk down to a neutron star that is a pulsar the first one identified and originally thought to be LGM! B Page 5

6 12) 12 Same as 10 for the image shown, -- Ring Nebula in Lyra -- Star death stellar remnant -- The outer layers of a sun-sized star that had gone through its red giant stage has been blown away from the core. A: The core of the ancient star is now a white dwarf. B: The gas of the outer layers of the star is expanding away from the core. A B 8 13) 8 In Compline, a chapter of Honey from Stone (Hungry Mind Publishers, reprint 1997 ) Chet Raymo states: In our own sun there are 700 oxygen atoms, 400 carbon atoms, and two calcium atoms for every million atoms of hydrogen; these heavier atoms were created in stars antecedent to our sun, stars that illuminated the younger galaxy with a brilliant blue light. One hundred septillion (10 26 ) hydrogen nuclei were processed in the interiors of Vega-like stars to create the pebble in my hand This carbonate pebble in the palm of my hand is the ash of starlight In view of the fact that the universe was initially almost devoid of elements heavier than hydrogen and helium, write out an explanation of this statement for a friend or relative who has not studied science how can a pebble be the ash of starlight? Does it change your view of yourself to know that you re the ash of starlight? The elements we re made of other than hydrogen (which was formed in the Big Bang) are all formed within stars from lighter elements. In small stars, hydrogen is fused into helium, carbon, oxygen, nigtrogen, calcium and other elements lighter than iron. These are the primary elements of life as biological molecules are made primarily from CNO and H. The hevier elements such as iron, iodine, barium, gold, silver, lead and up to uranium could only have been made in a supernova, the explosion of a giant star, that took place before the Sun and Earth formed from the interstellar cloud. Knowing that I am literally made from star stuff the ash of starlight connects me with the entire cosmos and makes even the darkest night my home. Page 6