1. HD 61827 – Spectral Analysis Astr 8600 Class Project Presentation Paramita Barai 8 th Dec, 2003

2. Background HD 61827 – Star in Cluster (NGC 2439) RA = 07h 39m 49.3s Dec = -32  34 42.1  B mag. = 8.11 V mag. = 7.66 Spectral Type: O8 / O9Ib (1997 A&A…323L..49P) B3 Ia (Turner, 1977 AJ…82..805T) I think B3 supergiant Parallax = 0.63 mas

3. Spectra observed KPNO Coude Feed Telescope 2 observing runs : Oct 2000 – 8 spectra Dec 2000 – 17 spectra

7. Analysis Spectral Type No HeII in absorption Cooler than O supergiant Strong carbon doublet absorption B3 Supergiant

8. Single star with convective atmosphere Spectral lines varied by small amount & randomly H  in emission – double peaked, randomly varying Convective wind flow around star, atmospheric turbulence Stellar absorption lines affected by the emission from gaseous envelope

9. Obs Times Abs Radial Centroid vel Eq width ISM (t-2451000) Velocity of H-alpha of H-alpha line (HJD, days) of star emisison emission velocity 817.99210 69.7607 -43.966999 0.111366 -0.264551 818.98270 68.9000 -98.056278 0.103513 0.358755 819.98540 66.3713 -2.7476891 0.193890 -0.798865 821.98710 66.0539 75.885895 0.509803 -1.67593 822.98540 68.5903 74.879163 0.579271 -1.49449 823.99210 73.2484 66.727690 0.665814 -0.413824 824.98560 83.2103 56.756792 0.777624 0.456484 831.00170 76.7857 70.034462 0.648179 -1.75772 889.92740 60.6403 176.53778 0.266625 -2.08747 890.94870 66.3107 164.15621 0.312579 -1.21548 893.92980 65.9936 163.25417 0.180265 -1.11643 894.90550 64.7917 146.39896 0.227874 -1.25792 895.97320 67.4618 121.18486 0.312627 -0.111312 896.89940 71.1799 96.059732 0.412994 0.254858 896.96770 71.9758 95.080074 0.431571 -0.906800 897.89470 67.6174 88.220027 0.386711 -1.05064 897.96250 67.0272 90.077823 0.393263 -0.834035 898.90690 66.4012 109.73705 0.307043 -1.22143 898.96910 66.8032 118.42820 0.297144 -0.566621 899.90060 65.2533 141.49436 0.270036 -1.88504 899.96300 64.0225 152.54472 0.224368 -1.82733 900.89390 65.7604 138.76702 0.413018 -0.250673 900.95610 65.7114 135.16257 0.437835 -0.237383 901.90210 75.3950 116.85906 0.432203 -0.0681385 901.96500 75.3741 111.83913 0.474489 0.00000

12. Results Single, B3 supergiant Gaseous envelope around the star Varied with ~ 5 days periodicity More observations required to study the complex motions in the atmosphere accurately

13. Thank you all