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Autor:

Ernst Pollmann [ 26. Juli 2008, 09:57:05 AM ]

Betreff des Beitrags:

He lines in delta Sco

An Be-Stern-Interessierte der FG!
Folgende Nachricht sendete ich an die Be-Stern-Mailingliste:
--------------------------------------------------------------------
An: <mailto:BE-STARS@JISCMAIL.AC.UK (BE-STARS@JISCMAIL.AC.UK)>
Betreff: He lines in delta Sco

The He emission lines 6678 in delta Sco exhibit considerable changes between
February and July this year (see attachment):

1. change of the V/R ratio from V<R to V>R
2. change of the radial velocity of both peaks

Question:
Is there someone who can confirm this ?
Is there someone who is able to explain that phenomenon ?
-----------------------------------------------

Hier statements von Philippe Stee bzw. Richard Townsend:
--------------------------------------------------------

Zitat:

Dear Friends,
This effect might be due to the fact that He6678 can be formed in a
disk that is no more expending from the central star but falling back to
the
star and/or to an elliptical rotating ring where the ring is not centred
on the
central star.
The situation might be more complex since delta Sco might also have a
companion which is triggering the disk/ring formation or destruction
through
tidal effect on the circumstellar disk/ring.
Cheers,
Philippe

--------------------------------------------

Zitat:

Might?
It does! But if I recall correctly, the periastron distance of the
secondary is far to large for tidal effects to come into play. Also, the

outbursts seen over previous years by Sebastian Otero occur before
periastron.
cheers,
Rich---------------------------------------------------------E.P.

Dateianhänge:

Behavior_HeI6678_in_delta_Sco.jpg [ 58.58 KiB | 3436 mal betrachtet ]

Autor:	Ernst Pollmann [ 27. Juli 2008, 08:58:07 AM ]
Betreff des Beitrags:	He lines in delta Sco
---Ursprüngliche Nachricht--- Von: "Philippe Stee" Betreff: Re: He lines in delta Sco Datum: 26. Jul 2008 22:17 Hi, based on interferometric measurement from the GI2T, we estimate the size of the emitting region in He6678 to be 2.3 R* (<8.5 R* in Hbeta and 18 R* in Halpha) for gamma Cas see Stee et al. 1998, A&A, 332, 268. Thus He 6678 must originate very close to the star's surface. I would favor its formation thanks to a recent outburst in an rotating ring not centred on the central star... Is the double pics separation of He 6678 close to its vsin i ? You may also have a look to our recent paper on Achernar which try to explain the relation between the line intensity and the double peak separation see: Kanaan et al. 2008, A&A, 486, 785 Cheers, Phil ______________________________ Philippe STEE Chercheur - CNRS - Directeur PNPS UMR 6525 UNS-CNRS-OCA Responsable Equipe ESOM Observatoire de la Côte d'Azur Site de Grasse-Roquevignon Avenue Copernic [url=callto:06130]06130[/url] GRASSE - FRANCE Tel: (33) 4 93 40 53 52 Fax: (33) 4 93 40 53 33 ______________________________ ------------------------------- weitergeleitet von E.P.

Autor:	Ernst Pollmann [ 27. Juli 2008, 09:02:40 AM ]
Betreff des Beitrags:	He lines in delta Sco
---Ursprüngliche Nachricht--- Von: "Thom Gandet" Betreff: Re: He lines in delta Sco Datum: 26. Jul 2008 17:49 Hello, Yes! Halonen et al (2008) (http://fr.arxiv.org/PS_cache/arxiv/pdf/ ... 0988v1.pdf) found that the disk density between about 1-4R* had changed since Zorec et al (2007, A&A, 470, 239) determined the density variation. (This is based on H-alpha.) Would not HeI follow the same general density variations as H-alpha? Has the width between the peaks of the HeI 6678 line changed, Ernst? A couple of remarks about the binary: There is still controversy over the orbit of the binary. The Sixth Catalogue of Orbits of Visual Binary Stars gives i=48° and the magnitude difference between the components as 2.2 (based on minimum mag of A). Halonen found i=20° to fit their observations somewhat better. Isn't the periastron distance is more like 1R*? It would be very interesting to know what the gravitational field strength is like near periastron, compared to the Roche lobe constraints. Perhaps also non-radial pulsations could, given surface rotational velocities near critical and a boost from the nrp, Del Sco form a disk during periastron (comments, Rich?). It would be very interesting to see some orbital dynamical models for this highly eccentric binary. An updated interferometric orbit would be very helpful, too, since the last one was around 2000 (?). Best regards, Thom Gandet Lizard Hollow Obserrvatory Tucson, AZ USA http://www.lhobs.org ----- Original Message ----- From: "Ernst Pollmann" <mailto:ernst-pollmann@T-ONLINE.DE (ernst-pollmann@T-ONLINE.DE)> To: <mailto:BE-STARS@JISCMAIL.AC.UK (BE-STARS@JISCMAIL.AC.UK)> Sent: Saturday, July 26, 2008 2:22 AM Subject: Re: He lines in delta Sco Dear colleagues! First of all many thanks for all the comments ! Regarding the formation of a ring in this binary system, my friend and colleague A. Miroshnichenko gave at the spectroscopy conference in Heidelberg (in May this year) during his lecture the following assumption: - the Halpha line width decreased (no contribution from rapidly rotating part of the disk); - the line equivalent width (EW) decreased; - the brightness decrease in 2004/5 has been due to a decreasing mass loss from the primary Possible explanations: the disk became a ring ! The binary is coming to its next periastron in February - May 2011. Distance between the stars at periastron is d = 24 R1 Primary’s Roche lobe size ~ 0.6 d or ~ 15 R1 Consequences for Hálpha: Some ring material may flow into the secondary’s Roche lobe Ring may become denser and line emission will rise Single- or triple-peak profiles may be observed O.k., may be this will happen, we will see.... But we discuss about HeI6678 ! If in the current time situation, tidal effects because of the large distance between both components is hardly likely, and outbursts rather to be the reason, what could be the explanation for the change of the V/R ratio ? An elliptical rotating ring where the ring is not centred on the central star ? Ernst -----------------------------------------------------

Autor:	Ernst Pollmann [ 27. Juli 2008, 17:48:18 PM ]
Betreff des Beitrags:	He lines in delta Sco
Dear colleagues!<?xml:namespace prefix = o ns = "urn:schemas-microsoft-comoffice" /> Comments of Thom: Has the width between the peaks of the HeI 6678 line changed, Ernst? ...here the distances related to λ0 (6678.149) in km/s: 2008-02-02 > 230 2008-04-01 > 230 2008-07-23 > 190 What is the background of your question? Comments of Philippe: Thus He 6678 must originate very close to the star's surface. I would favor its formation thanks to a recent outburst in an rotating ring not centred on the central star... I agree, there are different other reasons too, which implicate the formation near the surface of the primary. Comments of Philippe: Is the double pics separation of He 6678 close to its vsin i ? *I´m sorry, but I don´t know yet the vsin i value of these lines.* Regarding elliptical orbit: I can imagine an elliptical orbit which is responsible for the change of the V/R-ratio. But this kind of orbit does not explain the monotonous shifting of the lines to higher wavelengths (or ?) ! Best wishes, Ernst

Autor:	Ernst Pollmann [ 28. Juli 2008, 05:56:43 AM ]
Betreff des Beitrags:	He lines in delta Sco
---Ursprüngliche Nachricht--- Von: "Philippe Stee" <Philippe.Stee An: <BE-STARS Betreff: Re: He lines in delta Sco Datum: 27. Jul 2008 22:54 Hi Ernst, the important point is not really the change of the radial velocity of both peaks but rather the change in the peaks separation. Event if it is more difficult to estimate the peaks separation for the 2008/07/23 spectrum (since the profile appears not really double peaked but rather with 3 peaks) it seems that the peaks separation taken 2008/07/23 is larger that those for 2008/04/01 and 2008/02/08 this is exactly what must be observed if the He6678 line is emitted in a rotation disk or ring that is slowly expanding from the central star. When it is ejected from the stellar surface its rotational velocity must be close to the stellar photosphere rotation, i.e. close to the vsini of the star which is about 165-175 km/s (from Simbad) than if the disk or ring is expanding and assuming a Keplerian rotation, its rotational velocity must decrease (as a function of the radius ^(-0.5)) and thus the double peaks separation must decrease as well as a function of time. If you told me that for 2008/07/23 the double peaks separation is about 190 km/s, this is very close to the vsini of the central star and this is another evidence that He6678 was just formed and ejected from the stellar photosphere, maybe thanks to a recent "outburst". The problem I see is that you also told me that for 2008/04/01 and 2008/02/08 the double peaks separation is 230 km/s which is unlikely since it should be smaller that 190 km/s... On the other hand a possible explanation is that we just see the disk/ring expansion as a function of time and thus the double peaks separation is also decreasing as a function of time (from 230 km/s to 190 km/s) and should still decrease till it will be diluted and will be no more observable. In the hypothesis, the vsini of the central star should be at least 230 km/s but it would not be the first time that the true rotational velocity is underestimated (for instance the inclination angle i is usually poorly estimated). Cheers, Philippe ______________________________ Philippe STEE Chercheur - CNRS - Directeur PNPS UMR 6525 UNS-CNRS-OCA Responsable Equipe ESOM Observatoire de la Côte d'Azur Site de Grasse-Roquevignon Avenue Copernic 06130 GRASSE - FRANCE Tel: (33) 4 93 40 53 52 Fax: (33) 4 93 40 53 33 ______________________________------------------------------------- E.P

Autor:	Ernst Pollmann [ 28. Juli 2008, 14:02:00 PM ]
Betreff des Beitrags:	He lines in delta Sco
"Dietrich Baade" > schrieb: Zitat: Hallo Herr Pollman, vielen Dank, dass Sie Ihre sehr interessanten Beobachtungen mitteilen. Die Aenderungen in der Geschwindigkeit sind ungewoehnlich gross. Andererseits ueberdecken die Beobachtungen einen Zeitraum von fast einem halben Jahr, so dass instrumentelle Durchbiegungen durchaus eine Rolle spielen koennten. Ich nehme an, das Ihr Spektrograph im Cassegrain-Fokus montiert ist. Ist das richtig? Fuehren Sie die Belichtungen des Vergleichsspektrums immer in einer Standardstellung des Teleskops (z.B. im Zenith) aus oder immer nahe an der aktuellen Beobachtungsposition? ...hallo Herr Baade, vielen Dank für Ihre kritische Anmerkung, die ich gottlob wie folgt beantworten kann: Seit ich mit neuem C14 in der STW zur Spaltspektroskopie Nov./2007 übergegangen bin, wird nach jeder Spektrenserie eine Neon-Kalibrationsaufnahme bei ebenfalls stets gleicher Belichtungszeit (60 sec) angefertigt. Dies geschieht in immer gleichbleibender Position des Teleskops plus Spektrograph (im Cassegrainfokus) an Teilkreisen: im Meridian bei Deklination: -30° (delta Sco: ~ 23°) So ist es mir heute möglich, die Kalibrationsgenauigkeit, hier (zunächst) ausgedrückt als Wiederholgenauigkeit der Dispersion (in Angstr./Pix) im Kalibrationsspektrum, für den fraglichen Zeitraum (02/2008-07/2008) zu dokumentieren: 0.245086 0.245303 0.245086 0.244000 0.244761 0.244491 0.244882 0.244285 0.244411 0.244594 0.244306 0.244110 0.244702 0.244922 0.244410 0.243275 0.246268 Die Standardabweichung vom Mittelwert (0.24469719) beträgt danach 0.00062861 (= 0.25689 %) Mit dieser Dispersionsgenauigkeit wird ein jeweiliges delta Sco-Summenspektrum in Wellenlänge skaliert. Vergleiche der gemessenen Wellenlängen der Wasserdampflinien (hier verwende ich die Wellenlängen der UVES-Spektren von Herrn Hanuschik aus 2006) mit diesen UVES-Wellenlängen, führte bisher zu einer Standardabweichung zwischen 0.0039 - 0.015 Angstr. Die Größenordnung dieser Standardabweichung bei der Bestimmung der Wellenlängen der HeI6678-Linien liegt somit deutlich unterhalb des gemessenen Verschiebungsbetrages (zwischen 2008/02/08 und 2008/07/23) von 2.2 Angstr. Beste Grüße, Ernst Pollmann

Autor:

Ernst Pollmann [ 29. Juli 2008, 13:00:54 PM ]

Betreff des Beitrags:

He lines in delta Sco

Hallo Roland!

Z.Zt. wird ein Beobachtungsergebnis von mir - Hel6678-Emissionen in delta Sco - in der Be-Star-Mailingliste diskutiert.
U.a. geht´s dabei um den Verschiebungsbetrag (Radialgeschwindigkeit) der Doppelpeakemission (siehe Anhang).

Herr Dietrich Baade (ESO) schrieb nun in diesem Zusammenhang:
man kann zur genauen Bestimmung von Verschiebungen als sehr bequemes Werkzeug eine Kreutzkorrelationsfunktion berechnen.

Da diesbezüglich meine mathematischen Kenntnisse wie Möglichkeiten begrenzt sind, würde ich dich fragen wollen, inwieweit du hier behilflich sein kannst.

Beste Grüße,
Ernst

Dateianhänge:

Behavior_HeI6678_in_delta_Sco.jpg [ 58.58 KiB | 3408 mal betrachtet ]

Autor:	Roland Bücke [ 29. Juli 2008, 13:36:38 PM ]
Betreff des Beitrags:
Hallo Ernst, das wäre kein Problem. Da ich davon ausgehe, dass die zeitlichen Änderungen von Interesse sind, könnte man als Korrelationsmaske eines der delta Sco - Spektren verwenden. Man bekäme dann die Verschiebungen in Bezug auf diesen Zeitpunkt. Ich benötige dafür die Spektren in ganz normalem Textformat (Wellenlänge, Intensität). Du kannst mir ja mal einige Spektren mailen. Wenn der Test positiv verläuft, ist es für mich keine große Arbeit, eine ganze Zeitserie auszuwerten. Gruß Roland

Autor:	Ernst Pollmann [ 29. Juli 2008, 17:57:38 PM ]
Betreff des Beitrags:	He lines in delta Sco
Weil ich weis, dass es unter den Forumslesern einige Teilnehmer gibt, die durchaus an Interesse daran haben, hinsichtlich des Themas im Betreff auf dem Laufenden zu bleiben, leite ich die jüngste Stellungnahme von Th. Gandet aus der Be-Star-Mailingliste hierhin weiter: ---------------------------------------------------------------------------- Mustn't any model take into account the multiple components of the emission lines? Looking at the spectra, it seems a difficult probalem to determine what is a separate "ring" and what are V/R components of other "rings". Measurements of the separation of the peaks may provide a way of sorting that out. If we are seeing rings, each will rotate at a somewhat different velocity. If a disk is involved, then the changes will tell if the disk is expanding or collapsing. There seems to be two physical effects going on in Delta Sco, yes? One is the ejection of material from the photosphere, the other is the formation of "blobs" of gas in the disk or ring(s) 9probably from viscosity affects?). The blobs then rotate in a more or less Keplerian fashion, eventually to fall back closer to the star. About the orbit: the orbit inclination is not well determined - values between 20° and 48° are in the literature. The only directly observed value of it, from interferometry, depended primarily on incomplete coverage of the orbit because of the high eccentricty and long period. There also remains a lot of uncertainty about the orbital eccentricity, which will affect the periastron distance. It would be good to have i and e better constrained! Would the periods and modes of nrps be affected by the secondary at periastron passage? There would have to be a change in gas denisty in the photospher, is that correct? My question is a separate one from whether the nrps contributed to the disk formation. Sorry for the long posting and probably dumb questions! There is a very interesting set of spectra that shows the changes in various lines in Delta Sco between 1995 and 2006. H-beta and HeI 5876 are shown, and it's interesting to compare them with Ernst's recent profiles. The paper is by Galazutdinov and Krelowski, in ApJ, 2006, 637, 342. Cheers, Thom Gandet ------------------------------------------------------------

Autor:

Roland Bücke [ 04. August 2008, 21:09:24 PM ]

Betreff des Beitrags:

He lines in delta Sco

Hallo Ernst,

hier die Ergebnisse meiner Auswertung im Anhang
als Excel-File. Ich habe sowohl die Halpha- als
auch die HaI6678-Emissionen mit SpecRaVE (also
Gaußfit) und Kreuzkorrelation (KK) ausgewertet.
Alle Ergebnisse sind von der Erdbewegung befreit,
also heliozentrisch. Da die KK nur
Geschwindigkeitsänderungen gegenüber einer
Referenz liefert, habe ich alle Werte einheitlich
auf dein erstes Spektrum JD=2454505.3 bezogen.
Beide Methoden reagieren natürlich auf etwas
unterschiedliche Weise auf Profiländerungen,
dennoch zeigen sie die gleichen Tendenzen. Mehr
würde ich erstmal nicht herauslesen wollen, da
man aufgrund der wenigen Messpunkte noch keine
Aussagen über die Streuung treffen kann.

Herzlicher Gruß
Roland

Am 13:01 29.07.2008 schrieben Sie:

Zitat:

Hallo Roland!

Z.Zt. wird ein Beobachtungsergebnis von mir -
Hel6678-Emissionen in delta Sco - in der Be-Star-Mailingliste diskutiert.
U.a. geht´s dabei um den Verschiebungsbetrag
(Radialgeschwindigkeit) der Doppelpeakemission (siehe Anhang).

Herr Dietrich Baade (ESO) schrieb nun in diesem Zusammenhang:
man kann zur genauen Bestimmung von
Verschiebungen als sehr bequemes Werkzeug eine
Kreutzkorrelationsfunktion berechnen.

Da diesbezüglich meine mathematischen Kenntnisse
wie Möglichkeiten begrenzt sind, würde ich dich
fragen wollen, inwieweit du hier behilflich sein kannst.

Beste Grüße,
Ernst

Dateianhänge:

RVneu.xls [18.5 KiB]
145-mal heruntergeladen

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