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Die Farben Der Fixsterne

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ASTRONOMISCHE NACHRICHTEN. N2 3657-58. Band 153. 9-10. ~~ ~~ Die Farben der Fixsterne. Von H. Osthf in C6ln. I. oo weiss I gelblicbweiss Obwohl ich mich schon seit a5 Jahren mit den Stern- 2 weissgelb (weiss und gelb zu gleicheo Theilen) farben beschiftige, liegen diesem Artikel Beobachtungen nur 3 hell- oder blassgelb zu Grunde, die ich in den Jahren mit einem 1885-1893 4 reingelb terrestrischen Fernrohr (t. R.) von 34 mm Objectivoffnung, 5 dunkelgelb a8 cm Brennweite, f. Vergrosserung und von 18 1893-1899 6 rothlichgelb (gelb (iberwiegt) mit einem Steioheil'schen Refractor (bezeichnet mit 4 Zoll.) von mm Objectivoffnung, cm Brennweite und 40f. 7 rothgelb (gelb und roth zu gleichen Theilen; orange) 108 162 8 gelblichroth (roth tiberwiegt) Vergr6sserung ausgeftihrt habe. 9 roth mit geringer Spur gelb 10 roth. 1. Der Beobachtungsraum war stets verdunkelt. Meinen Absichtlich habe ich die bisher iiblichen, vie1 zu un- Kopf sammt dem Ocularende des Fernrohrs verhtillte ich bestimmten Bezeichnungen schwefel-, strohgelb, feuer-, kupfer-, durch ein schwarzes Tuch. Die Beobachtungen wurden im blutroth und dergleichen vermieden. Dunkelo niedergeschrieben und die Farbe stets durch eine Der Endpunkt der Scala kano beliebig verlingert Ziffer ausgedrtickt. Nur in den dringendsten Fallen wurde werden, z. 9. durch wkhrend der Beobachtungszeit die Laterne geoffnet, urn die Sternkarte nachsehen zu konnen. Sonst bestimmte ich mir I oo hell unbekannte Sterne durch Beziehung auf bekannte. Nach I I mittel rein roth. Schluss der Beobachtungen, noch in der Nacht, spatestens 12 dunkel I am folgenden Morgen habe ich die Notizen durchgesehen und die Sterne identificirt. Vor Beginn eines jeden Beob- An den Anfang kann man setzen: achtungsabends nahm ich Einsicht in das Programm, kiim- - io glanzend merte mich aber nie urn die schon vorhandenen Beobachtungen. rein weiss. o matt Bei zu hellem Mondschein, unruhiger Luft und zu dunstigem Himmel habe ich nie Farben geschitzt. Jeden Stern habe ich solange fixirt, bis der Farbeneindruck un- Durch Jahre lange Anwenduog auf viele Sterne mit veranderlich feststand. Aus zahlreichen Abenden erhielt ich Tausenden von Schatzungen habe ich die Brauchbarkeit der Scala erprobt und gefunden, dass sie den VerhPltnissen am als mittlere Dauer eioer Farbenschatzung 2.2 1 Minuten. Die Zeit des Einstellens des Sterns und des Niederschreibens Fixsternhimmel wirklich entspricht, solange es sich um ge- der Beobachtung abgerechnet, bleiben fur das Fixiren selbst ntigend helle Sterne handelt. Geniigt aber die Helligkeit nicht mehr, so verwandelt sich weiss in grau, gelb in braun, 11/~-a Minuten, weil es sich nur um hellere Sterne handelte, bei denen der Sucher nicht angewandt zu werden brauchte. orange in rothbrauo. Auch rothbraun und broncefarben Die Sterne wurden scharf eingestellt. Stets ist mit voller treten auf. Das Gewimmel der kleinsten Sterne erglPnzt Objectivohung beobachtet; bei dem 4 Zoll. ist spater eine schliesslich eintonig grau. Thaukappe vorgesetzt worden. Was die erforderliche Anzahl Die Farben blau und grUn sind subjectiv. Sie ent- der Schitzungen betrifft, um die Farbe eines Sterns im Mittel stehen, wenn der Beobachter den Einfluss fremden Lichtes moglichst sicher zu erhalten, so halte ich nach erlangter - gleichzeitigen sowohl wie vorausgegangenen - nicht ver- Uebung 5- 10 fur ausreichend, die auf moglichst ebenso mieden hat. Zu diesem gehijren der Schimmer des stern- viele Abende zu vertheilen sind. besaten Himmels sowie der Metalltheile des Instruments, 3. ferner Mondschein, sowie tiberhaupt erhelltes Gesichtsfeld. Meine Farbenschatzuogen sind in der Scala von Schmidt Diese Bemerkungen finden jedoch keine Anwendung ausgedrlickt, deren Stufen ich folgendermaassen definirt habe : auf die wirklich blauen Begleiter farbiger Doppelsterne. II I 43 365 7 ’ 44 4. Tab. I. Haufigkeit der Farben der Sterne des Catalogs nordlich vom Aequator. 4 ~611.Refr. Scheinb. Gr. I/ I’ 1 2O Irn I - 3 I I I - 2 4 10 I 3 2 5- 3 - I4 16 -4 ‘3 I1 4 4 64 49 33 36 21 124 60 44 86 88 1 var. 2 I -6 Sa. 99 in o/o der Gesammtzahl 056 1 12.0 Unter der Einschrinkung, dass der weisslichste und Von weisslichen sind nur die hellsten sicher als solche zu der r6thlichste Stern ihren Rang immer nur fur ein be- erkennen, gewohnlich rnit blau gemischt. stimmtes Fernrohr behaupten, bezeichne ich als den geringst Durch diese Bestimmungen lasst sich der Farben- gefarbten der Sterne meines Catalogs, giiltig fiir den 4 Zoll., wechsel der Nova Cassiopeiae von 1572 aufklaren. (Vgl. Sirius pit 006, demnlchst Rigel = 0?9. Der farbigste ist Zollner, Photom. Unters. S. 248). Anfangs weiss (> Sirius), 19 Piscium = 808. Hierbei sind die Veranderlichen aus- ging die Farbe durch gelb (< a) zu roth tiber (zrn). Solch geschlossen worden. Zu diesen gehort p Cephei mit 8Co. ein Farbenwechsel findet nun nie bei der Lichtabnahme Unter den rnit blossem Auge sichtbaren Sternen bleibt dem- eines Sterns statt, einerlei aus welcher Ursache diese erfolgen nach Herschel’s Granatstern einer der farbigsten, wenngleich mag., Die Erscheinung deutet auf eine Katastrophe. Der diese Farbe selbst rnit blossem Auge nicht erkennbar ist. nun bei weiterer Lichtabnahrne eintretende bleifarbene Too (albedo sublivida) ist physiologischen Ursprungs und durch 5. Lichtschwache hervorgerufen, bei welcher die eigentliche Um die Farbenangaben aus der Zeit vor Erfindung Farbe unkenntlich wurde. des Fernrohrs controlliren zu konnen , habe ich Farben- schatzungen rnit unbewaffnetem Auge angestellt und als Hellig- 6. keitsgrenze, bis zu welcher die Farben erkennbar sind, ge- Zur Ermittelung des Einflusses der Instrumente auf funden : die Farbe bieten sich die von mir mittelst dreier Fernrohre Bei orangefarbenen Sternen etwa zmg erlangten Beobachtungsreihen dar. I) gelblichen n 2 2.0 . Tab. 2. Unterschiede der Farben: 4 2. - t. R. Farbe 5’” )I iiberh. -- 4m - 1?4 - 1 c2 - - - 1.1 -1.0 -1OI - IF”I - I .2 -0.8 -0.4 -0.6 - 1.2 -0.8 -0.7 -0.6 -0.9 -1.1 - 1.0 - 0.6 -0.7 -0.8 - 0.8 -0.4 -0.5 - 0.6 - - 0.3 - 0.4 ~- uberh. -0.9 Hiernach sind im Durchschnitt alle Farben im kleinen Ausser mit jenen beiden Fernglasern habe ich noch t. R. intensiver gesehen worden als im 4 Z., aber nicht in eine dritte Reihe rnit dem Sucher des 4 Zollers zu erlangen gleichem Maasse, vielmehr ist deutlich ein Gang nach den gesucht. Sie ist jedoch nicht ganz zu Stande gekommen und Farben vorbanden. Hingegen bleibt das Verhaltniss der deshalb aus dem Cataloge fortgeblieben. Ich gebe sie hier. Der Farbenangaben der beiden Instrurnente innerhalb jeder Farben- Sucher (S) besitzt 2 7 mm Objectivoffnung bei 24 cm Brenn- stufe ziernlich constant fir die verschiedenen Helligkeiten. weite und 9 mal. Vergrosserung. Stern Vgl. Farbe Stern Vgl. Farbe Stern Vgl. Farbe Stern Vgl. Farbe I I 1 I - 1 1 I 1 a Andr. 4 2C5 d Andr. 5 700 @ Andr. 4 7?1 B Arietis 4 3:o 6 Cass. 4 3.0 a Cass. 7 6.7 a Urs. min. 2 4.8 y Andr. 3 6.3 7 Pegasi 3 2.0 y D 3 3.3 a Triang. 2 4.5 a Arietis 9 6.3 145 365 7 46 - - - - - - Stern Vgl. Farbe Stern ilgl. Farbe Stern Irgl. Farbe - - - ~ - /3 Triang. 2 3C5 5 Aurigae 3 7?0 a Ursae 4 y Sagittae 2 7% a Ceti 4 7.3 as 5 4. I 79 2 Y Cygni 4 4.9 y Persei 2 6.0 y Orionis 2 2.0 a Bootis 4 aa 4 3.4 e' 4 7.3 /3 Tauri 4 I .8 @ Coronae 2 y Delphini 2 6.3 B B' 9 2.7 a Orionis 4 6.6 a> 2 E Cygni 4 6.0 a' I 4.3 ,9 Aurigae 5 2.2 w Herculis 5 5. 2 5.8 d* 6 7.8 rj Geminorum 2 7.8 8 CYPi 4 E Pegasi 2 7.3 5. 3 3.0 ru) 2 7 *8 a Sagittae 2 'I> 2 7.0 ED 2 2 2 2 0.5 YB 3.0 BR 1, 5.5 7 Tauri 2 6.0 a 2 4 2.3 y Aquilae 3 Pm 2 5-5 a2 7 6.4 a Canis min. 2 4.0 d Cygni 3 Bs 7.3 L Aurigae I1 1.3 8 Geminorum 5 5.7 a Aquilae 4 n2 I .8 2 I: Es 3 5.0 8 Ursae 2.5 Bei der Bearbeitung der folgenden Tabellen sind die wachweisbar ist. Mit steigender Vergrosserung nimmt die sechs Verhderlichen E Aurigae, a Cassiopeiae, T,I Geminorum, Intensitat der Farbe zu und zwar die der weisslichen wiel a Orionis, /3 Pegasi und e Persei fortgelassen und die Farben starker als die der rothgelben. des S. bei der Eintheilung als Grundlage angenommen worden. 7. Tab. 3. Unterschiede der Farben: S. - 4 2. (56 St.) - Zur Ermittelung des Einflusses des Mondscheins steht mir nur ein geringes Material zur Verfiigung. Ich pflegte Farbe I" 2" 3" 4'" 5" iiberh. 1 1 1 I 1 I nur hochst selten in der Zeit uber das I. Viertel hinaus zu beobachten, weil die Helligkeit der Sterne dann zu sehr IC - - - 105 - - IC5 verringert wurde. 2 - +0?6 +O.I - +0.4 3 OCO +0.8 +0.4 - oC4 +0.6 In den beiden folgenden Tafeln sind die Differenzen +0.8 +0.7 - +0.8 im Sinne (Beob. im 3) - (Beob. in Abwesenheit des 3) +0.9 - +0.4 +0.8 zu verstehen, sodass also eine negative Differenz anzeigt, +0.7 +0.7 +0.6 +0.6 dass die Farbe im Mondschein heller geschatzt wurde. tiberh. 1 +0.7 I +0.8 1.+0.6 I +0.5 1 +0.9 1 +o.i Tab. 5. Einfluss des Mondscheins. - t. R. -Tab. 4. -Unterschiede der Farben:- S. - t. R. (55 St.) Farbe tiberh. Farbe I" 4" tiberh. 2c +0?03 3 +0.02 -0?02 - +o.o 1 lC - - -2C5 - - 2?5 4 -0.i5 -0.23 +oCg5 -0.
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  • Annual Report / Rapport Annuel / Jahresbericht 1996

    Annual Report / Rapport Annuel / Jahresbericht 1996

    Annual Report / Rapport annuel / Jahresbericht 1996 ✦ ✦ ✦ E U R O P E A N S O U T H E R N O B S E R V A T O R Y ES O✦ 99 COVER COUVERTURE UMSCHLAG Beta Pictoris, as observed in scattered light Beta Pictoris, observée en lumière diffusée Beta Pictoris, im Streulicht bei 1,25 µm (J- at 1.25 microns (J band) with the ESO à 1,25 microns (bande J) avec le système Band) beobachtet mit dem adaptiven opti- ADONIS adaptive optics system at the 3.6-m d’optique adaptative de l’ESO, ADONIS, au schen System ADONIS am ESO-3,6-m-Tele- telescope and the Observatoire de Grenoble télescope de 3,60 m et le coronographe de skop und dem Koronographen des Obser- coronograph. l’observatoire de Grenoble. vatoriums von Grenoble. The combination of high angular resolution La combinaison de haute résolution angu- Die Kombination von hoher Winkelauflö- (0.12 arcsec) and high dynamical range laire (0,12 arcsec) et de gamme dynamique sung (0,12 Bogensekunden) und hohem dy- (105) allows to image the disk to only 24 AU élevée (105) permet de reproduire le disque namischen Bereich (105) erlaubt es, die from the star. Inside 50 AU, the main plane jusqu’à seulement 24 UA de l’étoile. A Scheibe bis zu einem Abstand von nur 24 AE of the disk is inclined with respect to the l’intérieur de 50 UA, le plan principal du vom Stern abzubilden. Innerhalb von 50 AE outer part. Observers: J.-L. Beuzit, A.-M.