High Resolution EUV Spectroscopy of Feige 24 Martin Barstow Department of Physics & Astronomy .
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Transcript of High Resolution EUV Spectroscopy of Feige 24 Martin Barstow Department of Physics & Astronomy .
![Page 1: High Resolution EUV Spectroscopy of Feige 24 Martin Barstow Department of Physics & Astronomy .](https://reader036.fdocuments.in/reader036/viewer/2022062422/56649eb75503460f94bc1211/html5/thumbnails/1.jpg)
High Resolution EUV Spectroscopy of Feige 24
Martin Barstow
Department of Physics & Astronomy
www.le.ac.uk
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Introduction
• Background – EUVE results• J-PEX instrument• Science goals of Feige 24
Observation• Results of 2008 J-PEX flight• Future prospects
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Science background
• Limitations of ~0.5-1.0Å resolution spectroscopy with EUVE
• Detection of photospheric, interstellar or circumstellar He II
• The composition and structure of white dwarf atmospheres
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Helium in EUV Spectra
HZ 43
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-B2B
Helium in EUV Spectra
Helium I Helium II
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Interstellar Helium
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EUVE - Homogeneous Fe Mixture
G191-B2B
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EUVE - Stratified Fe
G191-B2B
requires ISM HeII/He~75%
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The J-PEX SpectrometerR~6000 (δλ=0.04Å)
Ion etched, blazed grating.MoSi multilayers for high reflectionSpherical figure, 2.2m focal length
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Nitrogen IV Oxygen IVHelium II
J-PEX
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10σ
5σ
3σ
1σ
2σ
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Pre-CV Feige 24
• Period = 4.23d• Teff(wd) = 62,000K
• Kwd ~ 50 km s-1
• γtotal ~ 70 km s-1
• vISM ~ -10 km s-1
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Feige 24 science goals
• Search for evidence of photospheric He– Measure H layer mass
• Measure the He II interstellar column density– Derive ionization fraction
• Search for circumstellar material• Exposure time shorter than planned
– Reduced signal to noise
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Black Brant 36.207
White Sands MissileRange
October 21st 2008
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b)
a)
c)
Feige 24; DA+dM
a) H-layer mass = 10-12.92M
b) H-layer mass = 10-13.5M
c) H-layer mass = 10-14M
NHe II = 3.9x1017cm-2
NHe I = 1.6x1017cm-2
He II/He = 0.72
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Conclusion• Achieved primary science goal
– Limits on H layer mass– Value of He II interstellar component (He
II/He = 0.72)
• Need longer exposure times and more observations– Translate J-PEX onto a satellite platform
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b)
a)
c)
Feige 24; DA+dM
a) H-layer mass = 10-12.92M
b) H-layer mass = 10-13.5M
c) H-layer mass = 10-14M
NHe II = 3.9x1017cm-2
NHe I = 1.6x1017cm-2
He II/He = 0.72
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Feige 24 simulation, exposure = 4000s
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SAGE
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EUV spectroscopy flight options
• In the USA– Low-cost conversion of rocket payloads
to ~6 month duration orbital instruments
– Response to forthcoming Explorer call
• In Europe– Submission to latest M-class mission call
• We need your support... please contact me for involvement ([email protected])