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Part 2 2015 WIRO and Spectral Analysis RESEARCH ON STARS, GALAXIES & QUASARS Emission & Absorption Lines WIRO Telescope When heated every element gives off light. When this light is decomposed using a prism it is found to be made up of a series of ``lines'', that is, the output from the prism is not a smooth spectrum of colors, but only a few of them show up. This set of colors is unique to each element and provides a unique fingerprint: if you know the color lines which make up a beam of light (and you find this out using a prism), you can determine which elements were heated up in order to produce this light. Similarly, when you shine white light through a cold gas of a given element, the gas blocks some colors; when the ``filtered'' light is decomposed using a prism the spectrum is not full but shows a series of black lines (corresponding to the colors blocked by the gas); see Fig. 8.3. For a given element the colors blocked when cold are exactly the same as the ones emitted when hot. The University of Wyoming's 2.3-meter telescope is located at the Wyoming Infrared Observatory (WIRO) about 25 miles southwest of Laramie, WY on the summit of Jelm Mt. and at an altitude of 9656 ft. (Elev.: 2943 m; Long: 105d 58m 35s.5 west; Lat: 41d 05m 49.4s). This site (469 Jelm Mtn. Road) was chosen because: (1) the dryness of the air, an important consideration for infrared astronomy since moisture strongly absorbs infrared radiation, (2) comparatively low turbulence in the air above the mountain, (3) a dark night sky, (4) close proximity to the University of Wyoming, and (5) pre-existing road, electricity and phone lines since Jelm was formerly used by the US Forest Service and BLM as a fire lookout station. The wavelength of the emission or absorption lines depends on what atoms are molecules are found in the object under study. What atoms or molecules exist depend on: temperature chemical composition. Kirchhoff's Laws The spectrum of an object is the variation in the intensity of its radiation at different wavelengths. Objects with different temperatures and compositions emit different types of spectra. By observing an object's spectrum, then, astronomers can deduce its temperature, composition and physical conditions, among other things. Kirchhoff's Laws are: A hot solid, liquid or gas, under high pressure, gives off a continuous spectrum. A hot gas under low pressure produces a bright-line or emission line spectrum. A dark line or absorption line spectrum is seen when a source of a continuous spectrum is viewed behind a cool gas under pressure. Harvard ComputersWomen Astronomers American astronomer whose painstaking classifications included an important early catalog of stellar spectra, and whose work assisted Ejnar Hertzsprung in his verification of a distinction between dwarf stars and giant stars.. How far to that galaxy? Galaxy Spectra The overall spectrum of a galaxy is simply the combined spectrum of all the stars and other radiating matter in the galaxy. As galaxies vary in structure and relative composition of star type and gas their spectra will vary. The classification scheme for galaxies developed by Edwin Hubble and based on photographic images of the shape of galaxies is now supplemented by comparison of their spectra. Stellar Spectra There are many key aspects of stellar Researchers spectral graphs that indicate whether the N ICHOLE BUCZYNSKI-- CHEYENNE WY object is a single star, a galaxy, or a quasar CAROL FOLEY – UNITY NH (or something else, like a binary star JOE MEYER– LANDER WY system, etc.) Below this is explained and illustrated. FINDINGS Antonia Maury 1866 - 1952) Types of Astronomical Spectra OVERVIEW L.A.S.S.I. Thicker “black body” look (data distribution looks thicker) indicates the object is a star. The spectrum of a star (one shown a the right from our data collection at WIRO) without an atmosphere would be a smooth curve. Photons from star core heat up gas in star’s atmosphere. Electrons in the gas increase energy levels, but eventually decrease energy levels, which in essence changes the direction of the photons from the core. So what we are able to “view” is absorption of photon energy, whereas in reality the energy was simply redirected. A lot of drops in a spectral graph means a lot of absorptions, and indicates the presence of a star versus a galaxy or quasar.. Absorption wavelength locations indicate elements in star, according to what cooler stuff in atmosphere of star is made of. In summary, a star’s hot core causes absorption in the cooler stellar atmosphere. LASSI: Launching Astronomy: Standards & STEM Integration NAME OF POSTER (AGAIN) Presenters/Authors 700 600 500 400 Series1 300 200 100 0 0 1000 2000 3000 4000 5000 Wavelength (Angstroms) 6000 7000 8000 9000 10000 Flux/brightness (ergs/sec/cm^2) vs. wavelength 90 The overall spectrum of a galaxy is simply the combined spectrum of all the stars and other radiating matter in the galaxy. Emission spike means gas in galaxy has been heated up by many stars, indicating galaxy. 80 70 60 50 Series1 40 To measure the distance to a galaxy, we try to find stars in that galaxy whose absolute light output we can measure. We can then determine how far away the galaxy is by observing the brightness of the stars. Such stars can help us measure the distance to galaxies 300 million light years away. If a galaxy is too far away for us to distinguish individual stars, astronomers can use supernovae in the same manner, because the light output of supernovae at their peak brightness is a known fact. Supernovae can be used to measure the distance to galaxies as far as 10 billion light years away. When light passes through a prism, it separates into the colors that make it up. White light changes to a swath of colors. This rainbow is called a spectrum. You can make spectra (the plural of spectrum) in many ways: with a prism, with drops of water (as in a real rainbow), or with gratings (like in the glasses you can get). Scientists build special instruments to separate light, usually with gratings. These instruments are called spectrographs. When astronomers pass the light of a star through a spectrograph, they get a spectrum of the star. The spectrum looks like a regular rainbow of colors—except that there are dark lines in it. Flux/brightness (ergs/sec/cm^2) vs. wavelength 30 20 10 0 0 1000 2000 3000 4000 5000 Wavelength (Angstroms) 6000 7000 8000 9000 10000 Flux/brightness (ergs/sec/cm^2) vs. wavelength 250 Emission lines/spikes indicate super heated gases, and many different emission spikes mean multiple elements present, indicating quasar. Quasars consist of a galaxy with a black hole in middle of it, causing GPE to turn into KE, and the KE coming out as pure light. Spectral emission lines are WIDER because energies emitted move toward and away from us as a quasar’s stellar objects revolve about the center of the black hole, causing blue and red shifting, creating wider/thicker emission lines. 200 150 Series1 100 50 0 0 1000 2000 3000 4000 5000 Wavelength (Angstroms) 6000 7000 8000 9000 10000