R Ophiuchi , A Mira-Type Variable Star
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Transcript of R Ophiuchi , A Mira-Type Variable Star
R Ophiuchi, A Mira-Type Variable Star
Vikas AgteyEmily BerrymanCaroline Fletcher
Linda GongAaron McNeely
Dan Walsh
University of Notre Dame QuarkNet
Center
Summer, 2013
Advisor: Dr. Dan Karmgard
Astrophysics Group Projects
• Major projects:– Variable star photometry– Asteroid astrometry (IASC)– General stargazing, telescope use,
astrophotography• Outreach: Solar observing for Sensing the
Cosmos; Observatory visit for iLED• Field Trips: Adler Planetarium, Kalamazoo Air
Zoo, Joshua Tree Museum
Variable Stars
• Stars that change brightness over time• Project: Measure the brightness (magnitude)
of one or more variable stars• Collect and submit data to the American
Association of Variable Star Observers (AAVSO)
CCD Photometry
• Photometry: The measurement of the brightness of stars
• Use telescope and CCD camera to determine the brightness of variable stars
• Values estimated in “magnitude”
CCD & Telescope• Telescope: Celestron CPC
1100, 11-inch Schmidt-Casssegrain reflector, located at Morrison Observatory, Notre Dame
• CCD: SBIG ST8-XE• Software:
– CCDSoft: Take and combine images
– MaximDL: Photometry tool to measure stellar magnitudes
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Raw images Flat fields Dark fields
Image for photometry
Estimating Magnitude• For our unknown variable
star, we compare its brightness to nearby stars of known magnitude (arrows) contained within the CCD image area
• Use MaximDL software to perform magnitude measurements
• Submitted magnitude measurements to AAVSO (observer MMAE)
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AAVSO Screenshot
R Ophiuchi• We selected R Ophiuchi, a variable star in the
constellation Draco• R Ophiuchi is a “Mira-type” or long-peroid
variable star• Star changes on average from magnitude 7 to
13.8 over a period of 10 months (306.5 days)• R Ophiuchi was predicted to peak around
June 20 (Sky & Telescope, July 2013)
R Oph
Ophiuchus
Newsworthy in 2011 [click]
AAVSO Star Chart
R Ophiuchi ResultsDate Time Magnitude* Uncertainty**
6/21 12:34 am 7.80 0.00172
6/29 1:44 am 8.30 0.02274
7/10 11:28 pm 8.26 0.00263
7/14 1:24 am 8.16 0.00104
7/18 11:46 pm 8.13 0.00053
*7—13.8
**1/SNR
R Ophiuchi Light Curve
SS Cygni• SS Cygni, a well-known variable star in the
constellation Cygnus• Cataclysmic variable (dwarf nova class)• Magnitude 12.2 to 8.3• Outburst every 4-10 weeks, duration of 1-2 weeks• Consists of red dwarf and white dwarf in fast orbit
(6.5 hours)• Newsworthy [click]
SS Cygni Results
Date Time Magnitude* Uncertainty**
7/14 10:06 pm 12.136 0.0168
7/18 11:09 pm 12.233 0.01149
*7—13.8
**1/SNR
SS Cygni Light Curve
Barnard’s Star
• One of the nearest stars to earth (6 LY)• Exhibits greatest proper motion of any star• Project: Take images of Barnard’s Star each
summer, record its proper motion
Barnard’s StarJuly 2013
Asteroid Astrometry
• Goal: Measure the position of known asteroids
• Provide reports of asteroid position to the Minor Planet Center
• We worked as a group within the International Asteroid Search Collaboration (IASC)
Procedure
• Obtain CCD images of predicted NEO asteroid positions
• Stack images, search for moving objects using Astrometrica software
• Prepare reports in a standard format, submit to Dr. Patrick Miller at IASC
Weather
Clear Sky Charts [click]
Sensing the Cosmos
L to R: Emily, Vikas, & Linda
Field Trips