Forum der Vereinigung der Sternfreunde

Forum of the German Amateur Astronomy Association
Aktuelle Zeit: 14. August 2020, 04:17:35 AM

Alle Zeiten sind UTC+02:00




Ein neues Thema erstellen  Auf das Thema antworten  [ 9 Beiträge ] 
Autor Nachricht
 Betreff des Beitrags: WR140 6.2.08 H beta RV measurement
BeitragVerfasst: 09. Februar 2008, 14:53:43 PM 
Offline
Meister
Benutzeravatar

Registriert: 25. Oktober 2006, 23:43:13 PM
Beiträge: 741
Wohnort: Cumbria England
I have moved down to the H beta line to see if I can get a good measure of the O star RV (RV measurement is something quite new for me. I hope to learn more at Heidelberg) I was hoping to compare my result with the graph fig 1 of the Marchenko paper but that seems to be plotted around a mean of zero and I cannot see a reference to the mean RV of the system. Does anyone know this value?

Thanks
Robin


Dateianhänge:
wr140_6feb06_19-03UT_norm4950.png
wr140_6feb06_19-03UT_norm4950.png [ 9.02 KiB | 4371 mal betrachtet ]
Nach oben
   
 Betreff des Beitrags: WR140 6.2.08 H beta RV measurement
BeitragVerfasst: 10. Februar 2008, 16:37:37 PM 
Offline
Meister
Benutzeravatar

Registriert: 17. Dezember 2006, 15:08:21 PM
Beiträge: 904
Wohnort: Neckarsteinach
Hi Robin,
Zitat:
I have moved down to the H beta line to see if I can get a good measure
of the O star RV (RV measurement is something quite new for me. I hope
to learn more at Heidelberg) I was hoping to compare my result with the
graph fig 1 of the Marchenko paper but that seems to be plotted around a
mean of zero and I cannot see a reference to the mean RV of the system.
Does anyone know this value?
Why do you think the velocity has been corrected by Marchenko? I assume
they quote heliocentric velocities. Do you find significant disagreement?
Zitat:
Thanks
Robin
Best regards,
Otmar


Nach oben
   
BeitragVerfasst: 10. Februar 2008, 18:29:59 PM 
Offline
Meister
Benutzeravatar

Registriert: 25. Oktober 2006, 23:43:13 PM
Beiträge: 741
Wohnort: Cumbria England
Hi Otmar,
Zitat:
Hi Robin,
Why do you think the velocity has been corrected by Marchenko? I assume
they quote heliocentric velocities. Do you find significant disagreement?
If they are absolute heliocentric velocities then it looks like I have to get more practice measuring RV.

If I take my wavelength of 4861.278 A and apply a heliocentric correction of -0.047 A (from VisualSpec) this gives me -0.099 A relative to the rest H beta (4861.33 A) which is -6.1km/s.

If I am reading the graph correctly, at the current phase Marchenko fig 1 gives about +10 km/s for the O star. I had hoped to get closer.

I also measured Deneb on the same night. I will check that against the published figure.

Robin


Nach oben
   
 Betreff des Beitrags: WR140 6.2.08 H beta RV measurement
BeitragVerfasst: 10. Februar 2008, 18:40:39 PM 
Offline
Meister
Benutzeravatar

Registriert: 17. Dezember 2006, 15:08:21 PM
Beiträge: 904
Wohnort: Neckarsteinach
Hi Robin,
Zitat:
I also measured Deneb on the same night. I will check that against
the published figure.
Unfortunately, Deneb shows also radial velocity variations. You should
observe proper radial velocity standards, if you want to check your
spectrograph. See e.g.

http://obswww.unige.ch/~udry/std/std.html
Zitat:
Robin
Otmar


Nach oben
   
BeitragVerfasst: 10. Februar 2008, 18:44:33 PM 
Offline
Meister
Benutzeravatar

Registriert: 25. Oktober 2006, 23:43:13 PM
Beiträge: 741
Wohnort: Cumbria England
Zitat:
I also measured Deneb on the same night. I will check that against the published figure.
I get an RV for Deneb of +0.5km/s compared with the published figure of -4.5kms so it does not seem to be a systematic calibration error. Perhaps my SN is just not high enough.

Robin


Nach oben
   
BeitragVerfasst: 10. Februar 2008, 18:47:09 PM 
Offline
Meister
Benutzeravatar

Registriert: 25. Oktober 2006, 23:43:13 PM
Beiträge: 741
Wohnort: Cumbria England
Zitat:
Unfortunately, Deneb shows also radial velocity variations. You should
observe proper radial velocity standards, if you want to check your
spectrograph. See e.g.

http://obswww.unige.ch/~udry/std/std.html
OK Otmar,

Thanks
Robin


Nach oben
   
BeitragVerfasst: 14. Februar 2008, 16:26:15 PM 
Offline
Meister
Benutzeravatar

Registriert: 25. Oktober 2006, 23:43:13 PM
Beiträge: 741
Wohnort: Cumbria England
Zitat:
it does not seem to be a systematic calibration error.
I think I might have found the source of the problem. My neon calibration lines (LHIRES III) are moving 0.5-1 pixel between the start, middle and end of the sets of exposures. (1 pixel = 37km/s) I am not sure if the cause is thermal or mechanical.

Best
Robin

Google Deutsch

Ich glaube, ich könnte gefunden haben, die Ursache des Problems. Mein Neon-Kalibrierung Zeilen (LHIRES III) bewegen 0.5-1 Pixel zwischen dem Beginn, Mitte und Ende des Sets von Forderungen. (1 Pixel = 37 km / s) Ich bin mir nicht sicher, ob die Ursache ist, thermische oder mechanische.


Nach oben
   
 Betreff des Beitrags: WR140 6.2.08 H beta RV measurement
BeitragVerfasst: 14. Februar 2008, 17:33:55 PM 
Offline
Meister
Benutzeravatar

Registriert: 17. Dezember 2006, 15:08:21 PM
Beiträge: 904
Wohnort: Neckarsteinach
Hi Robin,
Zitat:
I think I might have found the source of the problem. My neon
calibration lines (LHIRES III) are moving 0.5-1 pixel between the start,
middle and end of the sets of exposures. (1 pixel = 37km/s) I am not
sure if the cause is thermal or mechanical.
You could make a series of exposures without moving the telescopes. Then
you could see if the problem has a mechanical cause.

best regards,
Otmar


Nach oben
   
BeitragVerfasst: 14. Februar 2008, 18:59:18 PM 
Offline
Meister
Benutzeravatar

Registriert: 01. August 2006, 16:08:56 PM
Beiträge: 3828
Wohnort: 26725 Emden
Zitat:
I think I might have found the source of the problem. My neon calibration lines (LHIRES III) are moving 0.5-1 pixel between the start, middle and end of the sets of exposures. (1 pixel = 37km/s) I am not sure if the cause is thermal or mechanical.
Hello Robin,

such problems i had also with my Lhiress III. There ist a construction problem with the neon lamp in Lhires. The lamp has to be vertical over the slit !!!!!!!
And the flip mechanism has to work reproducible. If there is a hoirzontal shift vertical to the slit of the lamp during flipping, than you get strong mismeasurements in calibration !
Ciao
Lothar


Nach oben
   
Beiträge der letzten Zeit anzeigen:  Sortiere nach  
Ein neues Thema erstellen  Auf das Thema antworten  [ 9 Beiträge ] 

Alle Zeiten sind UTC+02:00


Wer ist online?

Mitglieder in diesem Forum: 0 Mitglieder und 1 Gast


Du darfst keine neuen Themen in diesem Forum erstellen.
Du darfst keine Antworten zu Themen in diesem Forum erstellen.
Du darfst deine Beiträge in diesem Forum nicht ändern.
Du darfst deine Beiträge in diesem Forum nicht löschen.
Du darfst keine Dateianhänge in diesem Forum erstellen.

Suche nach:
Gehe zu:  
Powered by phpBB® Forum Software © phpBB Limited
Deutsche Übersetzung durch phpBB.de