csm epsilon aurigae project

Sally SeebodeScience Educator SMUHSD

Dean Drumheller, Steve Howell, Don Hoard, Sally Seebode, Darryl Stanford

Take Data

Hardware: Losmandy G11 Mount Meade 8” SCT @f/6.3 SBIG Self Guided Spectrograph (SGS) ST7XME cameraSoftware: TheSky 6- accurate mount control CCDSoft –image acquisition Maxim DL –image acquisition IRAF –spectra processing

Raw Data Frame

Reduced Spectrum: standard methods using IRAF3800 – 4600A; 5800 – 6600A

•EquivalentWidth

•Full Width Half

Max•Velocity

Minimum three students make measurements for each spectra, data averaged and plotted.

Equivalent Widths (eqw): the width of a standardized rectangle representing the area of the absorption line. EQW relates to the flux.

Exaggerated for emphasis

Full Width Half Max (FWHM): the width of the absorption line at half it’s maximum value. Changes in FWHM indicate velocity variations which relates to the temperature and composition of disk.

Velocity: Measure the central wavelength to determine if object is moving toward or away from you and at what relative velocity.

Small portion of data.

“If I knew what I was looking for this would be much easier.”

Student motivation more important than math/science literacy

IRAF hard to get on high school computers

Teacher collaboration helpful Lots of support for astronomy education: NITARP, AAVSO, Lift Off, Project Astro, etc.

Variation in absorption of various elementsIndicative of varying density of the diskPossible Ring Structure

Eqw minimumEqw maximumLeadbeater/Stencel plateaus

Measure the days of a min or max

Find fraction of orbit this represents:width of ring = min or max days/(27.1 * 365)

Represent fraction angle (* 360)

Knowing the radius 18.1 AU, use small angle approximation (sin or tan) to find ring width

18.1 AU

Fraction of orbit= (20 days ) *360 (27.1*365)= 0.73

Ring Width = tan 0.73 * 18.1= 0.23 AU

Ring mins and maxs are roughly 0.2 AU

1990 – S. Ferluga: disk is actually a series of concentric rings with gaps between them (like rings of Saturn)

Ferluga (1990, A&A, 238, 270)

Our result predict an outer ring at a radius of 3.3AU, a wider ring with radius 2.8 AU, and two

small inner rings with a radius near 1.5 AU. These

two small rings may represent the one inner ring. Our results are similar to Ferluga’s

prediction.

Our result predict an outer ring at a radius of 3.3AU, a wider ring with radius 2.8 AU, and two

small inner rings with a radius near 1.5 AU. These

two small rings may represent the one inner ring. Our results are similar to Ferluga’s

prediction.

Take data 2 or more times every week

Examine the spectra for more information: H alpha emission and absorption components

Changing molecular bands (CN, CH) FWHM interpretation