Quasars, Galaxies, and Stars…Oh my!

Quasars, Galaxies, and Stars…Oh my!!Sarah Turner, Mary Flynn, Andrea Hayden

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W BACKGROUND Astronomy spectra give a snapshot of objects in space that give off light. We used data collected at the WIRO observatory near Laramie to learn about three different objects. By analyzing the data in a spectrum, we can determine whether we were looking at a galaxy, a quasar, or a star. The spectra for each of these objects can tell us about their temperature (whether they peak in hot/blue areas, red/cool areas, or somewhere in between), their composition (by aligning the spectra with spectra of known elements), and their velocity (by looking at their redshift). It can also give information about their distance by using redshift.

Data Collection

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Given these sets of data, our task was to determine what each spectra was. We looked at features such as wavelength, where peaks were, the presence of emission and /or absorption features, slope trends, and the overall shape of each graph. These features helped us to determine what type of object was represented in each graph. We determined that of the nine images, three were stars, three were galaxies, and three were quasars. We then did further analysis to learn more about the three spectral images taken on June 29th.Additional descriptions are provided below.

Galaxies are made up of many, many stars. Because there are billions of stars, the spectra features of a galaxy are not clear. There are several emission and absorption lines and the spectrum tends to “level off” or “plateau” rather than trending upward or downward. There is one high emission spike located at approximately 6900 indicating Hydrogen is present. That emission feature is very narrow (looking almost like a single line, unlike the broad one in the quasar).

2015 UW College of Education Research Symposium

We analyzed data collected at the WIRO observatory on two separate nights, as well as one additional set of data from the Sloan Digital Sky Survey. Data is reported as columns of numbers telling brightness and wavelength which we then exported to Excel to create a visual image of the spectra. In total, we looked at 9 spectra. The images featured below are the three spectral observations from June 29, 2015.

AN ANALYSIS OF SPECTRAL DATA SARAH TURNER, MARY FLYNN, ANDREA HAYDEN

Quasars have several emission features including a high spike indicating Hydrogen Alpha. The broad emission line of the Hydrogen indicates that the object is spinning at a high speed, and the only objects we know of with enough mass and gravity to cause that are black holes. The height of the spectra is indicative of this Quasar emitting a lot of light. The level of brightness and the broadness of the emission lines tells us that this in a Quasar. Stars have several

absorption features. This stellar spectra tells us this is a red star and low in temperature. According to our graph this star peaks at 8175, so Wien’s Law tells us the maximum temperature is about 3670°K. However, we do not know the exact temperature of this star because the upward trend continues off of our chart, so it could be even cooler. Our data does not give us the true height which means we cannot calculate an accurate temperature of the star.

FutureWork

Future exploration could look at multiple spectra of stars to compare them and see how stars differ from each other. (Similar to the work the Harvard Computers did.) Additional information could also be gathered by looking at different grating angles to view different parts of the non-visible spectrum. We would also like to look at characteristics of spectra for other sources of light, such as nebula, supernovae, planets, etc. It would also be interesting to look at data collected from satellites outside the atmosphere.

Participants in the 2015 LASSI summer institute had the opportunity to visit the University of Wyoming Infrared Observatory near Laramie Wyoming. The 2.3-meter telescope is located on the summit of Jelm Mt. and at an altitude of 9656 ft. This site 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. WIRO became operational in September of 1977 and it still ranks as one of the premier infrared observatories in the world. (http://physics.uwyo.edu/~chip/wiro/ )

WIRO

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f(x) = − 2.42191613842189E-06 x² + 0.0343870406815877 x − 74.1466822971005

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f(x) = − 2.87188834581425E-06 x² + 0.0431838974451395 x − 104.350350460876

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700f(x) = 1.82099450611809E-07 x² + 0.121431800278604 x − 429.699278313295

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