Sam Schonfeld Advisors Paola Testa and Steve Saar Contents Motivation Cross calibrating solar measurements Methods Finding Targets Tracking targets Modeling stellar emission Estimating Signal ID: 785714
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Slide1
Beyond the Limb
A Narrow Band EUV search for Background Objects with the AIA
Sam Schonfeld
Advisors: Paola
Testa and Steve Saar
Slide2Contents
Motivation
Cross calibrating solar measurements
Methods: Finding TargetsTracking targetsModeling stellar emission
Estimating Signal Methods: Preparing ObservationsOff-Limb Intensity DecaySatellite Path CorrectionConclusions
AIA 171
Å
AIA 193Å
Slide3Motivation: Comparing Sun and StarsSun is a Star at 1 AUSpatial resolution
Test stellar modelsThis proximity is also a problemDifficult to measure the Sun and anything else with the same instrument
Different telescopes use different techniquesPossible discrepancies between instruments
Slide4Motivation: The AIA
Constant full sun imaging from SDONarrow band EUV telescopesHigh resolution and cadenceChance to observe Sun and stars together
Objectives:Primary: Determine whether possible to observe background objectsSecondary: If possible, make observations
Slide5Methods: Can AIA Detect Stars?
Pros
Star is point a source
Sun is relatively dim
AIA is sensitive
Dynamic range ≈ 10
4
DN
Cons
Star is > 10
7
farther
Flux=L / (4
π
D
2
)
Extinction due to ISM
Object must be ≈10
3
more Luminous than Sun!
Slide6Methods: Candidate Objects
Stars
Quasar/AGN/Galaxy
Galaxy
ClusterUnknown
HD
199143
QSO J2137-1432
Abell
2426
J080311.1+202213
HD
206301
Pks
2349-014
Abell
193
J084029.9+182417
HD
210803
LEDA
1510700Abell 763J154426.3-201637 HD
15814
QSO
B0317+183J171209.5-231005 HD 244354 LEDA 97068J171227.5-232140 HD 245358 LEDA 23927J180037.6-232454 HD 245924 2MASX J12401929- 0349194Flare StarJ180824.5-230917 HD 58728 3C 279GJ 4282J182928.2-234743 HD 130819
Selected from ROSAT x-ray observations
Slide7Methods: Path Elimination
1 pixel ≈ 0.6 arc seconds
Slide8Methods: Remaining Objects4 Stars, 3 Galaxies, 2 Galaxy Clusters, 2 Unknown
Stars
Quasar/AGN/Galaxy
Galaxy
Cluster
Unknown
HD 199143
QSO
J2137-1432
Abell
2426
J080311.1+202213
HD
206301
Pks
2349-014
Abell
193
J084029.9+182417 HD 210803LEDA 1510700
Abell
763
J154426.3-201637 HD 15814QSO B0317+183J171209.5-231005 HD 244354 LEDA 97068J171227.5-232140 HD 245358 LEDA 23927J180037.6-232454 HD 245924J12401929- 0349194Flare StarJ180824.5-230917HD 58728 3C 279
GJ 4282
J182928.2-234743
HD
130819
Slide9Methods: Stellar EM Models
Emission Measure
Differential Emission Measure
Amount of emitting material
P(T)=emissivityUse models of similar starsScale with distance and luminosityAIA Temperature response functionsBased on atomic models
Argiroffi
et al. 2004
PZ Tel
94
131
171
193
211
335
Slide10Methods
: Predicted Count Rates
AIA exposure ≈ 2.9 sec
Slide11Methods: Observational Techniques
Track Single pixel across field for hoursIntegrate signalActs like a longer exposureTakes advantage of point source
Subtract out backgroundOff-limb coronal emissions
AIA 171
Å
Slide12Methods: Off-limb Coronal Emission
AIA 171
Å
Slide13Methods: Exponential Decay
Consistent with exponential decay of coronal density
Suggests AIA noise ≈3 DN
171
Å
94
Å
Slide14Methods: Image Offset Problem
SDO is in Orbit!
Dr. Bart De Pontieu
Earth
Geostationary
Geosynchronous
Corrected
EarthGeostationary
Geosynchronous
Corrected
April 2011
June 2010
Slide15ConclusionObservation appears possible but…Stellar sources produce count rates within the noise level
Future Work: to make observationsFinish orbit correctionsLonger exposures would allow observations
Off pointing from disk would increase number of targetsInclude non-stellar targets
Slide16SupplementalHD 199143PMS AeFe
HD 206301Variable RS CVn typeHD 210803
PMSHD 245924T-Tau type