Reach for the Stars Div. B

Transcription

1 Reach for the Stars Div. B Help session: March 6 th, 2016 Properties and evolution of stars especially star forming regions and supernova remnants Resources for test Two 8.5 x 11 inch two sided sheet Test on March 19, 2016 Test will include questions about a series of images projected onto the front of the room. 1

2 The room will be dimly lit (planetarium program is part of test) (red) flashlight strongly recommended. 2

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5 Study points Download planetarium software, Stellarium ( is good and free!!! Practice recognizing pattern of stars of constellations and stars listed on the rules sheet. Google the objects on the list and try to under stand how they fit into the birth and death of stars. Try to understand what a stars magnitude, luminosity and distance modulus means. Understand the inverse square law.. Memorization and conceptual understanding is required. 5

6 Test is in 2 parts Part 1 planetarium program Identical show repeated 3 times every hour Timed power point presentation Circles put around objects, constellations and stars name this Planets and the moon are off Part 2 Normal test, multiple choice, fill in blanks. Pictures shown as part of a timed power point presentation 6

7 Constellation and object in it Aquila Altair (star), W49 region (Weterhout 49) HII region Aquarius NGC7293, Helix Nebula Auriga Capella (star) Bootes Arcturus (star) Canis Major Sirius (star) What you may need to know Canis Minor Procyon (star) Carina* NGC3603 (giant molecular cloud, HII region), NGC3372 (great nebulae) Cassiopia Cas A, Tycho s SNR, NGC281, W3 Main Dorado* 30 Doradus, LMC Cygnus Deneb (a bright star), Cygnus X-1 Gemini Castor & Pollux (two stars in Gemini) Hydrus* NGC 602 (young open cluster of stars) Leo Regulus (star) Lyra Vega (star) Monoceros Rosette Nebula Ophiuchus Zeta Opiuchi, Keplar SNR Orion Betelgeuse, Rigel (stars) & M42 (Orion Nebula) Perseus Algol (variable star) Sagittarius Sgr A* Sagittaris A a radio source that is a massive black hole and center of our Milky way Galaxy M17, Omega or Swan or Horseshoe Nebulae or Lobster Nebulae M8 Lagoon Nebulae Scorpius Antares (red giant star that is the body of the scorpian) Taurus Aldebaran (star), M1 (the crab Nebula) Ursa Minor Polaris (North Star) Ursa Major Mizar & Alcor (second star(s) in the handle a binary) Virgo Spica (star) 7

8 W49A is an active star forming region lying at a distance of ~11 kiloparsecs from the Sun in the constellation of Aquila. W49A is clearly very young, with observations revealing several massive OB clusters lying within a giant molecular cloud that is still at an early stage of disruption. Large HII region. 8

9 NGC7293 A mere seven hundred light years from Earth, in the constellation Aquarius, a sun-like star is dying. Its last few thousand years have produced the Helix Nebula (NGC 7293), a well studied and nearby example of a Planetary Nebula, typical of this final phase of stellar evolution for a solar mass star.

10 NGC 3603 is a starburst region: a cosmic factory where stars form frantically from the nebula s extended clouds of gas and dust. Located light-years away from the Sun, it is the closest region of this kind known in our galaxy, providing astronomers with a local test bed for studying the intense star formation processes, very common in other galaxies, but hard to observe in detail because of their large distance. It is a large molecular cloud and HII region. 10

11 Carina Nebula (also known as the Great Nebula in Carina, the Eta Carinae Nebula, NGC 3372, as well as the Grand Nebula) is a large bright nebula that has within its boundaries several related open clusters of stars. It contains the large OB association, Carina OB1. 11

12 NGC281. NGC 281 is an H II region in the constellation of Cassiopeia and part of the Perseus Spiral Arm. It includes the open cluster, the multiple star, and several Bok globules. Colloquially, NGC 281 is also known as the Pacman Nebula for its resemblance to the video game character. Bok globules are dense dust and gas pockets likely containing new stars

13 Objects Tycho Super Nova Remnant (Type 1a) Cassiopeia Cas A (Cassiopeia A) Type II Super Nova remnant 13

14 "W3 is a Giant Molecular Cloud which lies around 6200 light years away in one of the spiral arms of our Galaxy. W3 Main is a region where many massive stars are being born. But these observations discovered that many brown dwarfs, small objects with too little mass to become stars, are also forming. Large HII region and molecular cloud. Optical and infrared 14

15 , green and blue represent lower and higher-energy X-rays, respectively, while red shows optical emission. Hundreds of X-ray sources are revealed in this central region of W3 Main. These bright point-like objects are an extensive population of several hundred young stars, many of which were not found in earlier infrared studies. These Chandra data show that W3 Main is the dominant star formation region of W3. W3 REGION IN x RAYS 15

16 Objects 30 Doradus (Tarantula Nebulae) Has molecular clouds and HII regions 16

17 The Tarantula Nebula (also known as 30 Doradus, or NGC 2070) in the Large Magellanic Cloud (LMC). The Tarantula Nebula has an apparent magnitude of 8. Its distance is about 49 kpc or 160,000 light years. Its absolute brightness is so great that if it were as close to Earth as the Orion Nebula, the Tarantula Nebula would cast shadows. It is the most active and largest starburst region known in the Local Group of galaxies. It has an estimated diameter of 200 pc or 650 light years. The nebula resides in the Large Magellanic Cloud. 17

18 Cygnus X-1 is a well-known black hole and galactic X- ray source in the constellation Cygnus. It was discovered in 1964 during a rocket flight and is one of the strongest X-ray sources seen from Earth, Cygnus X-1 was the first X-ray source widely accepted to be a black hole and it remains among the most studied astronomical objects in its class.

19 Cygnus X-1 Artist imagination 19

20 NGC 602 is the designation for a particular young, bright open cluster of stars located in the Small Magellanic Cloud, a satellite galaxy to our own Milky Way. Radiation and shock waves from the star cluster has pushed away much of the lighter surrounding gas and dust that compose the nebula known as N90, and this in turn has triggered new star formation in the ridges (or "elephant trunks") of the nebula. 20

21 Rosette Nebula (also known as Caldwell 49) is a large, circular H II region located near one end of a giant molecular cloud in the Monoceros region of the Milky Way Galaxy. The open cluster NGC 2244 (Caldwell 50) is closely associated with the nebulosity, the stars of the cluster having been formed from the nebula's matter. 21

22 Zeta Ophiuchi is an enormous star with more than 19 times the Sun's mass and eight times its radius. The stellar classification of this star is O9.5 V, with the luminosity class of V indicating that it is generating energy in its core by the nuclear fusion of hydrogen. This energy is being emitted from the outer envelope at an effective temperature of 34,000K, giving the star the blue hue of an O-type star. 22

23 Supernova 1604, also known as Kepler's Supernova, Kepler's Nova or Kepler's Star, was a supernova of Type Ia that occurred in the Milky Way, in the constellation Ophiuchus. Appearing in 1604, it is the most recent supernova to have been unquestionably observed by the naked eye in our own galaxy, occurring no farther than 6 kiloparsecs or about 20,000 light-years from Earth. Visible to the naked eye, Kepler's Star was brighter at its peak than any other star in the night sky, 23

24 M42 Orion Nebulae star forming region Large star forming region in Orion HII regions glow from the radiation from the new young stars in the core of the nebulae. Objects 24

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26 M17 or NGC th object in the Messier catalogue. Omega or Swan or Horseshoe Nebulae or Lobster Nebulae. region of star formation and shines by excited emission, caused by the higher energy radiation of young stars. these stars are not obvious in optical images, but hidden in the nebula. HII region. In Sagittarius. 26

27 Lagoon Nebula(catalogued as Messier 8 or M8, and as NGC 6523) is a giant interstellar cloud in theconstellation Sagittarius. It is classified as an emission nebula and as a H II region. The Lagoon Nebula was discovered by Giovanni Hodierna before 1654 and is one of only two star-forming nebulae faintly visible to the naked eye from mid-northern latitudes. Seen with binoculars, it appears as a distinct oval cloudlike patch with a definite core. In the foreground is the open cluster NGC

28 M17 NGC6618 Omega Nebula M8 Sgr A 28

29 Sgr A Sagittarius A X-ray source (black hole) at center of our galaxy Objects M1 Crab Nebulae Type II Supernova Remnant in Taurus 29

30 Star Charts ~8:00 pm in the evening before the day of the competition in Dover Delaware 30

31 All sky (South at bottom) M42 31

32 All sky (South at bottom) Constellations now shown 32

33 North 33

34 Mizar and Alcor in the Handle of the big dipper 34

35 North 35

36 East 36

37 South Rosette Nebulae M42 37

38 Zoom in on West, M42 M1 38

39 Star Charts ~5:00 am in the morning of the day before the competition in Dover Delaware 39

40 North, Tycho SNR Cas A NGC281 W3 main 40

41 East, Cygnus X-1 W49 41

42 South, Cygnus X-1 W49 Keplar SNR 42

43 Zoom in on South M17 M8 Sgr A 43

44 Zoom in on West, 44

45 Southern Hemisphere NGC3603 Large Magellenic cloud (LMC) with 30 Doradus Small Magellenic cloud (LMC) with NGC602 45

46 solar system condensed out of intersteller gas and dust Gigantic gas and dust clouds (left over material spewed out by supernovae) condensed b by self gravity into globules. The globules spun up due to conservation of angular momentum. Became a spinning disk. The gas reached a critical density at the center and a star was formed. Can t see the new star because it is cloaked in the gas and dust. Planets form as the surrounding material coalescences,

47 Early solar system evolution Early in the sun s life (as the planets were forming), the sun had a very strong solar wind (from flares) Charged particles streaming out of the suns atmosphere This solar wind was produced as the nuclear reactions in the core of the sun started. The sun produces a weaker solar wind today that fluctuates with the sunspot activity of the sun more sunspots, more solar wind. Solar wind storms cause the Northern Lights (auroras) This early strong solar wind pushed much of the material that had not been formed into planets out to the farther reaches of the solar system

48 Stellar Evolution Most stars are born in open clusters Pleiades (M45), NGC602 are examples W49A, M42 (Orion Nebula), M17, NGC3603, NGC3372, NGC281 W3, 30 Doradus are examples of a cluster in the making HII regions have many of molecular clouds that are forming new stars as open clusters. Open clusters don t stay as open clusters very long Stars that are less than ~2x the mass of our sun die as planetary nebulae NGC7293 (Helix nebulae) High mass stars die as supernovas with remnants (Type II supernovae remnants ) M1 (Crab Nebula), Cas A, Other special binary star systems Tycho s SNR die as type 1a super novae remnants Type 1a are important measuring sticks of the universe Cygnus X-1 is a binary star system with one component as a black hole (sucking material from its companion and making xrays) 48

49 HII regions and molecular clouds The radiation from new hot stars embedded in molecular gas and dust clouds will ionized the gas that is, an electron will be stripped from the atom of the gas. Much of that gas is hydrogen. The region of the gas cloud where hydrogen becomes ionized is called a HII region. This region is also called an emission nebulae HII regions show very characteristic emission lines in a spectroscope. 49

50 Brightness of Stars Needed to understand the Hertzsprung- Russell diagrams (H-R diagrams) Brightness measured as luminosity or magnitude Luminosity is the total energy output of a star Depends on size and surface temperature A star s magnitude is the logarithm of its luminosity Apparent magnitude (m) four factors Its temperature or color (wattage of a light bulb) Its size How far away it is If it is obscured by dust Absolute magnitude (M) Magnitude of a star when viewed from a fixed distance and without any dust in the way. 50

51 Luminosity, L Total amount of energy emitted by the star, Depends on the surface temperature (same as color) Hot (Blue) Yellow Orange Cool (red) Depends on the size The larger the star, the more surface area to emit the energy and the brighter the star Measured relative to our sun (sun =1) L>1 for Stars emitting more energy than our sun L<1 for Stars emitting less energy than our sun 51

52 A star s magnitude as brightness Magnitude is more often used to describe an objects brightness. The higher the magnitude the dimmer the object. The apparent magnitude (lower case m) of our sun is The apparent magnitude of a full moon is The apparent magnitude of the Sirius is -1 Dimmest star you see (in Wilmington) +3.5 Dimmest star you see in a dark sky sight +5.5 The absolute magnitude (capitol M) is the magnitude of the star / object if it was place a fixed distance away (10 parsecs = 32.6 light years). Our sun s absolute magnitude is

53 Distance Modulus It is a way that astronomers measure large distances it is simply the apparent magnitude less the absolute magnitude or = m M The higher the number the more distant the object Our Sun s distance modulus is = this is a very low number meaning that the sun is very close to us!! 53

54 Inverse square law The brightness of an object (star) decreases by the square of the distance between the observer and the object. if a light bulb looks like a 100 watt bulb at 10 feet, then at 100 feet it will look like a 1 watt bulb. Brightness (at distance b) = brightness (at distance a) x (a/b)x(a/b) Or = brightness (at distance a) x (a/b) 2 54

55 Categorizing stars by their spectra 1. Spectra can tell you the stars approximate temperature (blackbody radiation) 2. Absorption (dark) lines in a star s spectra give a finger print of elements that are seen in that spectral class of stars BUT emission spectra (bright lines against a dark background) are given off by nebulae glowing gas clouds like the HII regions described above. 55

56 Dark (absorption) lines in emission spectra (of stars) or bright lines in nebulea Electron transition from a lower energy state to a higher energy state adsorption line Electron transition from a higher energy state to a lower energy state emission line Below is the Balmer series of lines associated with electron transition in the hydrogen atom to and from the second lowest energy level H-α ( hydrogen alpha ) is an important line in both emission and absorption spectra. It has a wavelength of nm or 6563 Angstroms HII regions show the nm emission Absorption line seen in stars are used to classify them Other elements next slide 56

57 Spectral class of stars He+ lines H Balmer lines (B,A & F stars) Ca+ lines (F & G stars) Fe and neural metals K & M stars) TiO2 lines 57

58 Example of a star s spectra Strong hydrogen lines, B, A, and F type star No helium lines not a B star. ionized calcium (the H and K lines), This is an F type star 58

59 Hertzsprung-Russell Diagram -- Each dot is a star Y axis is always brightness or relative luminosity X axis is always temperature, color or spectral class A is main sequence B is horizontal branch C are supergiants D are white dwarfs 59

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62 Low mass star like our sun stops at carbon formation... 62

63 And fluffs off its outer layers to make a planetary nebulae and a white dwarf star.... NGC 7293,Helix nebulae 63

64 But a high mass star, have enough mass to fuse nuclear material all the way to iron. However, once iron accumulates in its core no net energy generation can be done by fusion of iron and... 64

65 It goes boom!!!!... A supernovae!!! (this is the M1, the Crab Nebulae) A spinning neutron star is inside this nebulae called a pulsar. 65

66 Cas A (Cassiopeia A) Type II Super Nova remnant 66

67 The ultimate fate of a star is dictated by one property: its mass Low mass stars fuse hydrogen to helium very slowly and live for a long time on the main sequence. High mass stars consume their fuel very rapidly and are on the main sequence for a short time Low mass stars end up as white dwarf, High mass stars as neutron stars or black holes after blowing up as type II or 2 supernovae 67

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69 Recap 1a. Stars are categorized by their spectral class 1b. Hertzsprung-Russell (H-R) diagram is a way to represent the evolution of stars 2. The Main sequence is the location of stars on the H-R diagram where stars spend most of their lives 3. Stars remain stable for long periods (on the main sequence) by balancing the force of gravity with the energy generated by nuclear fusion of hydrogen to helium in the star s core. 4. Red giant stars are generally caused by nuclear fusion in the shell and not the core. Elements heavier than helium are fused to carbon and then iron in the core of these stars. 5. Mass is the single most important property of a star that dictates its ultimate fate. 6. A more massive star has a shorter lifetime 7. Stars in a single cluster are all born at the same time 8. An old star cluster will show stars in many stages of life as a result of the different masses of the stars formed in the cluster. 69