David Dunlap Observatory

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David Dunlap Observatory
Slavek Rucinski Dept. Astronomy
Astrophysics University of Toronto
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History of DDO (1)

• The 74 inch (1.88m) telescope, made in 1933 DDO
  dedicated on May 31, 1935.
• Classical Cassegrain design concave primary,
  convex secondary.
• Largest in Canada (next in size, DAO Victoria, 72
  inch).

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History of DDO (2)

• Clarence Augustus Chant (1865-1956), the first
  DDO Director.
• Chant gave a lecture in 1921, David Dunlap in the
  audience. DD dies in 1924, but his widow Jessie
  allocates funds in 1926.
• Site selection 1930, purchase of land (180
  acres), the telescope the admin building for
  the total cost C200k.

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History of DDO (3)

• Variable stars in globular clusters (Helen S.
  Hogg).
• Radial velocity studies of binary stars (1st
  known stellar black hole, Cyg X-1).
• Radio-astronomy program (46m dish in Algonquin in
  1960).
• Small telescopes (0.5m, 0.6m, 0.6m at Las
  Campanas (1971-1997).
• Planetoids named in relation to DDO/DAA (Chant,
  Fernie, Heard, Inannen, Martinduncan, Northcott,
  Sawyer-Hogg, Shelton, Tremaine, van den Bergh,
  Toronto).

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Location

• Richmond Hill, access from Bayview Ave., N of
  16th Ave.
• 123 Hillsview Drive

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Aerial view
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Light pollution how serious?

• 1, 2 HgI 4047, HgI 4358
• 3, 4, 5 NaI 4665,4669, NaI 4748,4752, NaI
  4978,4983 (HPS)
• 7 NaI 5149,5153 (HPS)
• 8 HgI 5461
• 9 OI 5577 airglow
• 10 NaI 5683,5688 (HPS,LPS)
• 11 NaI 5890,5896 (HPS), wings extend 5500A -
  6500A with self-absorption
• 12 NaI 6154,6161 (HPS,LPS)
• 13 OI 6300 airglow

V-band 17.0-17.5 mag per arcsec2
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Weather - cloudiness

• Summer months better, but more haze.
• Winter nights usually cloudy, but sometimes
  crispy clear (and long).

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Efficiency

• Statistics for the years 1999 2004 (July-June)
• Year Nights Hours
• 1999 151/294 51 888 26
• 2000 168/315 53 986 28
• 2001 198/332 60 1121 32
• 210/332 63 1317 38
• 186/315 59 1090 32
• (Max 3459 hours 100 efficiency)

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1.88m telescope seeing

• Median seeing (FWHM) 1.7 arcsec, but large values
  (gt3 to 5 arcsec) happen.
• Best images are about 1.0 arcsec in size, so this
  is the quality of the main mirror of the
  telescope.

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1.88m Cassegrain
Cassegrain 1672
Gregory 1663
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The grating spectrographs

• The 1.88m Cassegrain telescope has two
  spectrographs
• The Cassegrain medium res. (R 700 12,000),
• The Echelle high res. sp. (R 50,000).

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Cass spectro
All reflective optics (except the corrective
plate). The blazed diffraction gratings (several
to select 100 1,800 lines/mm).
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Blazed diffraction gratings
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Stellar spectra

• The 2-D images are analyzed using IRAF (in UNIX)
• Image trace (2D-gt1D) background subtraction,
  wavelength calibration, rectification.

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Possible programs

• Radial velocity measurements of stars.
• Stellar atmosphere studies
• - Atmosphere parameters (densities, pressure,
  temperature)
• - Abundances.
• Interstellar matter.

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Radial velocities

• Doppler shift ??/? v/c (?ln ? v/c)
• Space velocities of stars galactic kinematics
  dynamics
• Pulsating stars radial and non-radial
  pulsations.
• Binary stars the only method to determine masses
• Rotating stars line broadening, surface features.

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Broadening Function and Cross Correlation
Function (1)
q 0.091
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BF and CCF (2)
The convolution reduces the amplitude, so that
the spectral signal (per pixel) is relatively
weaker for a given noise level. Hence a poorer
S/N.
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BF and CCF (3)
The goal is to obtain the BF. The CCF is a poor
substitute of the BF.
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BF and CCF (4)
Observed spectrum P ( convolution of the sharp
line spectrum S with a broadening function
B) P(x) ? B(u) S(x-u) du Computed CCF from
the observed P S C(z) ? P(x) S(xz) dx
? ? B(u) S(x-u) S(xz) du dx ? B(u) It is not a
surprise that C is a poor substitute of B CCF
is sensitive to the intrinsic broadening of lines
or insufficient resolution. (e.g, the well known
need to extricate the hydrogen lines).
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BF and CCF (5)
We express the convolution (of the sharp line
spectrum S with the broadening function B) P(x)
? B(u) S(x-u) du A set of over-determined
linear equations, to be solveed using any LSQ
method (SVD is preferable). Typically P and S
(used to construct Des) have dimension N
1000-2000 pixels. B has dimension M 100-200
pixels.
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DDO program

• DDO1 to 10 published in AJ (1999-2005), each
  with 10 RV orbits.
• DDO11 in preparation 100 orbits (a few
  additional publications, e.g., W Ser)
• DDO7, an explanatory paper with a discussion of
  uncertainties.
• Participants
• R.M.Blake, C.C.Capobianco, G.Conidis, H.DeBond,
  K.Gazeas, P.Ligeza, W.Lu, S.W.Mochnacki,
  W.Ogloza, T.Pribulla, W.Pych, P.Rogoziecki,
  S.M.Rucinski, G.Stachowski, J.R.Thomson

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10 papers

• DDO papers 1 to 10, each contains 10 RV orbits.
• DDO11 in preparation.

http//www.astro.utoronto.ca/DDO/research/binaries
_prog.html
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SX Crv
The smallest mass-ratio known q0.066 ? 0.002.
This information cannot be derived from the light
curve.
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SW Lac
A well known W-type system q0.776 ? 0.012.
?T/T 5. The temperature excess can be
determined to ? 1.
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TU UMi
A triple system probably intractable without the
BF technique. Individual BFs as vertical cuts in
a 2-D figure.
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Contact binaries in triple systems
We see a very high percentage of triple systems.
A new investigation of all available evidences
of triple multiple components of contact
binaries (Pribulla Rucinski 2005). Percentage
of triples/multiples, the lower limit 56 to
68. This is high as we are blind to some types
of companions (WDs, etc.) Preferential origin in
multiples?
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Limitations

• Magnitude limits
• Cassegrain spectrograph
• 11 mag 0.15A/pix (2160 l/mm)
• 15 mag 3.7A/pix (100 l/mm)
• Echelle
• 6 mag (0.05 A/pix)

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Time allocation

• Faculty, graduate students and senior
  under-graduate students, visitors.
• The schedule is prepared ½ month in advance on
  the basis of Web based application form.
• Observers must be present during the observations.

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Information contacts

• www.astro.utoronto.ca/DDO/
• rucinski_at_astro.utoronto.ca