- 學位論文
Measuring the Rotational Speeds of Classical Be Stars with IR Excess
Measuring the Rotational Speeds of Classical Be Stars with IR Excess
摘要
Classical Be stars為B型恆星且擁有紅外超量和光譜上存在著發射線的特性。這些恆星與主序前Herbig Ae/Be stars 不同，他們為轉速相當快的恆星且可能有些恆星轉速接近break-up。在星球附近有氣態環星盤，而這個環星盤可以解釋許多觀測的特性，包含了在被拋出物質所形成的envelope中的塵埃凝聚。我們利用NARIT所屬的泰國望遠鏡(TNT)取得echelle spectra，來算HD50138 (90.9±5.0 km/s)，HD 45677 (84.3±5.6 km/s) ，和HD 62532 (293.6±9.5 km/s)三顆Classical Be stars的轉速(vsini)。我們也估計了儀器所造成的譜寬，但是這些星球旋轉相當的快，所以我們預期儀器所造成的譜寬效應相對很小。 在本篇論文我們討論星球轉速與Be phenomena之間有無任何關係。
並列摘要
Classical Be stars are B-type stars with the characteristic emission spectra and infrared excess. These stars are distinct from the pre-main sequence Herbig Ae/Be stars and are known to be rapid rotators, some perhaps close to break-up. They are surrounded by gaseous disks, which are responsible for many of the observed properties, including plausibly the dust condensation in the ejected cooling envelopes. We present the echelle spectra taken by Tai National Telescope(TNT) of NARIT to derive the projected rotational speed (vsini) of three classical Be stars, HD50138 (90.9±5.0 km/s), HD 45677 (84.3±5.6 km/s), and HD 62532 (293.6±9.5 km/s). We are in the process of estimating the instrumental broadening, but these stars rotate very fast, so we expect the effect to be relatively small. We discuss how fast rotation may have played a role in the Be phenomena.