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A primer on DFDI, the MARVELS optical implementation, and pipeline flow MARVELS Science Review Brian Lee, June 21, 2011.

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Presentation on theme: "A primer on DFDI, the MARVELS optical implementation, and pipeline flow MARVELS Science Review Brian Lee, June 21, 2011."— Presentation transcript:

1 A primer on DFDI, the MARVELS optical implementation, and pipeline flow MARVELS Science Review Brian Lee, June 21, 2011

2 B1 B2 Input light Beamsplitter Mirror 1 Mirror 2 MARVELS basic physics Physical path difference: B2-B1 (DFDI Refs.: Erskine & Ge (2000), Ge et al. 2001, Erskine 2003, Ge 2002, Mosser et al. 2003, Mahadevan et al. 2008, van Eyken et al. 2010)

3 B1 B2 Input light Beamsplitter Mirror 1 Mirror 2 MARVELS basic physics Physical path difference: B2-B1 = N*lambda -> constructive interference (DFDI Refs.: Erskine & Ge (2000), Ge et al. 2001, Erskine 2003, Ge 2002, Mosser et al. 2003, Mahadevan et al. 2008, van Eyken et al. 2010)

4 B1 B2 Input light Beamsplitter Mirror 1 Mirror 2 MARVELS basic physics Physical path difference: B2-B1 = N*lambda + 0.5*lambda -> destructive interference (0.5*lambda of added delay) (DFDI Refs.: Erskine & Ge (2000), Ge et al. 2001, Erskine 2003, Ge 2002, Mosser et al. 2003, Mahadevan et al. 2008, van Eyken et al. 2010)

5 B1 B2 Input light Beamsplitter Mirror 1 Mirror 2 MARVELS basic physics Tilt mirror 2 over, so path length is a function of height Y ->Intensity is now a function of height Y = fringes Y Y

6 B1 B2 Input light Beamsplitter Mirror 1 Mirror 2 MARVELS basic physics Now consider slightly longer wavelength of input light Y Y Old lambda New lambda

7 B1 B2 Input light Beamsplitter Mirror 1 Mirror 2 MARVELS basic physics So multiple wavelengths look like this: Y Y lambda

8 MARVELS basic physics Zooming out in lambda, you’d see more strongly the dependence of periodicity of interference on wavelength. We call that the “interferometer fan”:

9 MARVELS basic physics m=1 m=2 m=3 m=4 Orders m are evenly spaced in y…

10 MARVELS basic physics (The MARVELS instrument can only collect a small cutout from the fan, with m~13000 and 5000A~ { "@context": "http://schema.org", "@type": "ImageObject", "contentUrl": "http://images.slideplayer.com/11/3160807/slides/slide_10.jpg", "name": "MARVELS basic physics (The MARVELS instrument can only collect a small cutout from the fan, with m~13000 and 5000A~

11 B1 B2 Input light Beamsplitter Mirror 1 Mirror 2 MARVELS basic physics (Have to add a low-resolution spectrograph so the fringes aren't all on top of each other) Y Spectrograph Y lambda

12 B1 B2 Input light Beamsplitter Mirror 1 Mirror 2 MARVELS basic physics Gradient in tilt of fringes across lambda is present, but fairly small. Y Spectrograph Y lambda

13 MARVELS basic physics Y lambda This was for a continuum light source...

14 MARVELS basic physics Y lambda Now multiply in a stellar source with absorption lines instead.

15 MARVELS basic physics Y lambda Now multiply in a stellar source with absorption lines instead. Note intersections.

16 MARVELS basic physics Y lambda Small x shift (e.g., from RV) of stellar lines gives larger y shift in intersections (amplification higher if slope is steeper)! Y shift X shift

17 MARVELS basic physics Y lambda Actual intensities follow a sinusoidal model, in theory. Y Inten. Continuum level Line depth

18 MARVELS basic physics Y lambda Y Inten. Continuum level Line depth Okay, now what messes this up?

19 Slanted spectral lines…

20 …tilted trace apertures…

21 …illumination profile of the slit…

22 …higher order distortions (time-variable?)…

23 …PSF (not necessarily constant across CCD)…

24 …integrated onto the CCD. Can you still spot the intersections?

25 Real data… Raw data (MARVELS): Above fringing spectrum, fully preprocessed:


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