The photoelectric effect

Transcription

1 Lecture in Beijing on astrometr Positions, motions and distances of stars Observations with the ESA satellite Hipparcos November 2009 Niels Bohr Institute - Copenhagen Astrometr lost and regained: From a modest experiment in Copenhagen in 1925 to the Hipparcos and Gaia space missions Niels Bohr Institute - Copenhagen Content: Onl about work leading to Hipparcos/Tcho Photoelectric effect, Bengt Strömgren Meridian circles in Brorfelde, Hamburg and Perth Hipparcos mission, including the Tcho experiment 2009: IAU Commission 41 in Rio de Janeiro, ELSA School in Heidelberg, Staff in Kroppedal Museum, Morelia Universit in Mexico, NAOC and ICSIT2009 in Beijing 26 November 2009, 32 slides Presentation at ICSIT 2009 in Beijing 1 Updated 23 November The photoelectric effect An atom emits an electron when hit b light with sufficientl high frequenc, i.e. high energ CCD: NOT photoelectric effect Experimental discover: In 1887 b Heinrich Hertz (German, ) while discovering radio waves; but he did not full realize! In 1887 b Wilhelm Hallwachs (German, ) on a zinc plate Named the Hallwachs effect Explained 1905 b Albert Einstein; Nobel prize 1921 Copenhagen meridian circle Photoelectric astrometr begins in 1925 Bengt Strömgren 1925 and 1933 Experiments with photoelectric recording of transits Courtes: Steno Museum, Aarhus 3 4 Switching mirror and integration proposed 1933 Star image moving across slits New meridian circle initiated b Bengt Strömgren 1940 installed in Brorfelde1953 Photo 1979 Times of switching t Behind the slits: Photocell Mirror Photocell integrates switches integrates Bengt Strömgren (1957) 5 6 1

2 M vision -1958: general principles of a new tpe of automatic measuring machine to magnetic tape to high speed digital computer E. Høg 1960: Scanner for photographic plates with spectra 7 8 Hamburg 1960: Recording on punched cards Scanning spectra Slits + Photon counting vs. Time => Astrometr + Photometr Ideas 1960 M innovations were much used but did not give me man publications. I won, however, the director Otto Heckmann s smpath and his confidence that I had even more to offer. Iris Photometer 9 Light intensit = Photons per second x1 x2 x t1 t2 time t1 t2 star x ~ time In France called: Une grille de Høg B. Strömgren 1933: slits + switching mirror 1930s: Photomultiplier Tube (PMT) and Image Dissector (IDT) developed Atomic bombs 1957 : Counting techniques E. Høg 1960 : Slits + counting >>> implementation on meridian circles 10 Visual meridian observations Hamburg ~1962 Aase and Erik 1963 in Hamburg G. Holst reading the declination circle J. von der Heide observing the star

3 First photoelectric slit micrometer for a meridian circle ~1964 Hamburg Meridian Circle 1966 Reading of the declination circle Developed for the Hamburg Expedition to Perth Visual micrometer Slit plate Photoelectric Zähllocher 13 Hamburg First slit micrometer on a meridian circle Perth Observator The GIER computer room GIER was transistorized transistorized Semi-automatic: Semiautomatic: Manual setting of telescope Photoelectric of declination circle and star Recording on punched tape Photon counts of the star are accuratel snchro d to UT. Therefore Crab pulsar Final catalogue in 1976 b E. Høg and J. von der Heide Perth meridian pavilion ~200 star observations per night ~ per ear!!! Fantastic for ears observing b a staff of

4 Space astrometr : A French vision Ideas and work in France Nice, Grasse, Paris, Lille: Pierre Bacchus, Strasbourg, and CNES in Toulouse; there was no space astrometr activit outside France in this period Pierre Lacroute 1967: Presentation in Prague Jean Kovalevsk 1974: European project Design of a scanning satellite Lacroute 1974: Expected stars ~3 mas Beam combiner with 40x x30 cm apertures 3 parts Two-dimensional 45 degrees 6 Photomultiplier tubes Pierre Bacchus & Pierre Lacroute (1985) Jean Kovalevsk (2005) Frascati 1974 in ESRO SP Beam combiners and mission Features later adopted for Hipparcos are in red Lacroute : 1974: Scanning satellite with a beam combiner Two-dimensional Beam combiner of 16, 5 or 3 parts Slit sstems Onl photomultiplier tubes (PMs PMs) Passive attitude control Spin axis related to orbit Lacroute also considered a Spacelab option First meeting of the stud group in Paris on 14 October 1975 Høg 3 Dec. 1975: One-dimensional Beam combiner of 2 parts Change its angle from 45 deg Modulating grid Image dissector tube Active attitude control Spin axis revolves around sun Star mapper with one PM Input catalogue The best I ever did for astronom 21 Design of a scanning satellite IAU GA 1976, Highlights of Astr., p.361 Høg : 1976: Expected stars ~4 mas with 16x16 cm aperture One-dimensional One image dissector tube + one PM 22 Slits + Photon counting vs. Time => Astrometr + Photometr x1 x2 x B. Strömgren 1933: Slits + switching mirror E. Høg 1960: Slits + counting P. Lacroute 1967: Go to space J. Kovalevsk 1974: European project + switching mirror E. Høg 1975: New design of mission L. Lindegren 1976: Data 1976: Data reduction Studies during 4 ears led to: ESA 1980: Hipparcos approval Ideas 1960 t1 t2 star In France called: Une grille de Høg x ~ time Hipparcos mission: Final results 1997: 16 volumes + 6 CD ROMs 23 Hipparcos and Tcho Focal plane of Hipparcos Tcho: New mission design Høg 1975 Mission approval Feb 1980 Tcho proposal Høg 1981 Launch 1989 Catalogues 1997 & 2007 Tcho-2 Catalogue in million stars 600 citations b 2009 Star mapper grid / Tcho Modulating grid 24 4

5 Hipparcos mission Science leaders Catherine Turon (2005) Jean Kovalevsk (2005) Lennart Lindegren (2003) (2009) Michael Perrman (2009) The project scientist and his four consortia leaders Hipparcos mission owes a thank ou to all the hard working scientists and ESA staff industr and tax paers Telescope of Hipparcos Schmidt tpe sstem D = 0.29 m F = 1.4 m Two fields on the sk Telescope and paload of Gaia Two SiC primar mirrors m 2 at at Launch 2012 Rotation axis (6 h) Basic angle monitoring sstem SiC toroidal structure (optical bench) Observing Figure courtes EADS-Astrium Astrium Superposition of two Fields of View Combined focal plane (CCDs) F = 35 m Two anastigmatic off-axis telescopes arcsec Astrometric Accurac versus Time Hipparchus/Ptolem stars Bradle - aberration Positions Parallaxes = Small angles All parameters The Landgrave of Hesse stars Tcho Brahe Flamsteed Lalande - 50,000 Bessel - 1 star FK Jenkins Hipparcos - 120,000 ROEMER - 45 million Proposal 1992 Argelander - 34,000 PPM - 379,000 Tcho million USNO Gaia million Gaia 23 million SIM - 10, / BC Year After Gaia what then??? How Gaia began August 1989: Hipparcos launched dialogue with Russian colleagues Proposal 1992: Scanning mission with CCDs 30 5

6 Fig. 1. Focal plane of Roemer The F.G.W. Struve medal awarded for the great contribution to development of ground-based and space astrometr b Scientific Council of the Central Astronomical Observator of the Russian Academ of Sciences Director of the CAO RAS A.V. Stepanov 31 Pulkovo Observator