-- AriannaSaba - 06 Mar 2019

https://www.eso.org/public/outreach/eduoff/cas/cas2002/cas-projects/germany_ngc1960_1/

https://arxiv.org/pdf/astro-ph/0003327.pdf

  • in a log L - log T plot, pp chain has a gradient of 5.6, CNO 8.4
Turnoff.png

  • New HR diagram computed. Fluxes were wrong last time. Data calibrated with the accepted values by adding a constant (the published B and V of the brightest star) to the magnitude V and B measured. The brightest star in the cluster is the brightest star also in our data. Now the published and the measured data agree better.
  • No errors shown because too big. Need to fix them.
m36_hr_comparison_aladin.png

  • turn-off is visible here in a plot of absolute magnitude vs Temperature
  • data converted according to these equations:
absolute magnitude: M = m_V - (5 * np.log10(D)) + 5 , D = 1330 pc

temperature: T = 4600 * ((1/((0.92*i)+0.17)) + (1/((0.92*i)+0.62))) , i = m_(B-V)

m36_hr_temperature.png

  • isochrones derived from these options and an age of 25 million years:
Schermata_2019-03-06_alle_17.40.46.png

  • tried to fit isochrone with a Z=0.02 to the HR diagram of V vs B-V, using data of absolute magnitude and B-V.
  • The data downloaded had to be corrected to match the diagram, (B-V) + 0.225 and M_v + 11.3
  • m36_hr_isochrone_modified-2.png Schermata_2019-03-07_alle_12.00.06.png

  • Without any modification of the data, other isochrones were plotted. This time the data plotted is in absolute magnitude vs B-V as well as the isochrones.
m36_isochronesFit.png

  • with the correction in B-V only, adding a value of 0.225, probably given by the reddening, as also explained by the paper, the data seems to match very wellm36_isochronesFit-2.png

  • tried to fit isochrones in a plot of absolute magnitude vs temperature but the curves were many orders of magnitude away from the data.
  • Temperatures in the isochrones range between 4 and 3, Mv goes from 9 to -5.

# Isochrone by Pietrinferni - Cassisi - Salaris - Castelli 2006 ::: Standard Model 
#===========================================================================================================================
# Scaled solar model & transformations (Castelli 1999) +  BaSeL Library (2002)
#===========================================================================================================================
#  Np= 2000   [M/H]= 0.058   Z= 0.0198   Y=0.273   t(Gyr)=  0.0250    normalized: 18  2 2006 
#===========================================================================================================================
#     (M/Mo)in       (M/Mo)     log(L/Lo)  logTe       Mv    (U-B)   (B-V)   (V-I)   (V-R)   (V-J)   (V-K)   (V-L)   (H-K)
#===========================================================================================================================
   0.5000000000   0.4999948559  -1.39726  3.58803    9.382   1.044   1.452   2.059   0.970   2.795   3.571   3.659   0.137
   0.5392574727   0.5392574727  -1.29476  3.59741    9.031   1.076   1.440   1.937   0.957   2.666   3.466   3.542   0.129
   0.5785149454   0.5785149454  -1.19031  3.60711    8.675   1.098   1.415   1.805   0.928   2.536   3.356   3.422   0.121
   0.6177724180   0.6177724180  -1.08264  3.61834    8.304   1.101   1.370   1.654   0.873   2.399   3.226   3.287   0.110
   0.6570298907   0.6570298907  -0.97368  3.63101    7.924   1.076   1.304   1.499   0.802   2.256   3.070   3.129   0.098
   0.6962873634   0.6962873634  -0.87105  3.64296    7.570   1.030   1.235   1.378   0.743   2.126   2.911   2.966   0.088
m36_hr_temperature_isochrone.png

JC: 
  • Was forced to update star detecton algorithm. Used histogram of raw data to re-influence threshold decision:
hist_rawinset_blue60.png

  • Much more successful at detecting stars now:

detectedstars_blue60.pngdetectedstars_clear60.png

  • Calculated separation between highest flux star in both frames and plotted histogram of minimum separation between this star in clear frame and all corrected star coordinates in the blue frame:

hist_distancetocorrectedstars.png

  • One can see the corrected coordinates of the highest flux star at d=0 and a subsequent spread for all the other stars
  • Next, I plotted both the clear frame centroids and blue frame corrected centroids on same plot to see if stars had matched well:

centroids_matchingstars.png

  • Following this, I plotted a HR diagram for these matched stars:
hr.png
Topic attachments
I Attachment History Action Size Date Who Comment
PNGpng Schermata_2019-03-06_alle_17.40.46.png r1 manage 85.6 K 06 Mar 2019 - 17:44 AriannaSaba  
PNGpng Schermata_2019-03-07_alle_12.00.06.png r1 manage 47.2 K 07 Mar 2019 - 12:00 AriannaSaba  
PNGpng Turnoff.png r1 manage 25.9 K 06 Mar 2019 - 18:44 AriannaSaba  
PNGpng centroids_matchingstars.png r1 manage 48.1 K 07 Mar 2019 - 15:33 JacobChambers  
PNGpng detectedstars_blue60.png r1 manage 167.7 K 07 Mar 2019 - 15:34 JacobChambers  
PNGpng detectedstars_clear60.png r1 manage 205.6 K 07 Mar 2019 - 15:34 JacobChambers  
PNGpng hist_distancetocorrectedstars.png r1 manage 30.9 K 07 Mar 2019 - 15:33 JacobChambers  
PNGpng hist_rawinset_blue60.png r1 manage 15.8 K 07 Mar 2019 - 15:34 JacobChambers  
PNGpng hr.png r1 manage 18.5 K 07 Mar 2019 - 15:33 JacobChambers  
PNGpng m36_hr_comparison_aladin.png r1 manage 29.4 K 06 Mar 2019 - 17:38 AriannaSaba  
PNGpng m36_hr_isochrone_modified-2.png r1 manage 38.0 K 07 Mar 2019 - 12:08 AriannaSaba  
PNGpng m36_hr_isochrone_modified.png r1 manage 36.7 K 07 Mar 2019 - 11:31 AriannaSaba  
PNGpng m36_hr_temperature.png r1 manage 29.7 K 06 Mar 2019 - 17:38 AriannaSaba  
PNGpng m36_hr_temperature_isochrone.png r1 manage 44.1 K 07 Mar 2019 - 11:58 AriannaSaba  
PNGpng m36_isochrones.png r1 manage 74.3 K 06 Mar 2019 - 17:38 AriannaSaba  
PNGpng m36_isochronesFit-2.png r1 manage 78.7 K 07 Mar 2019 - 12:19 AriannaSaba  
PNGpng m36_isochronesFit.png r1 manage 80.1 K 07 Mar 2019 - 11:42 AriannaSaba  
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Topic revision: r3 - 07 Mar 2019 - JacobChambers

 
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