论文标题
年轻星球主机DS TUC A的X射线耀斑
X-ray flares of the young planet host DS Tuc A
论文作者
论文摘要
简略。我们观察到40 Myr Old Star DS TUC A与XMM-Newton，并录制了两个X射线明亮的耀斑，第二个事件发生在第一个X射线后约12 k。从衰减末期到衰减结束的持续时间约为柔软的X射线（0.3-10 KEV）。耀斑还记录在200-300 nm的带中，并使用光学监视器的UVM2滤波器记录。紫外线中耀斑的持续时间约为3 k。观察到的紫外线带和X射线中的峰值之间的延迟是对加热阶段的探测，然后蒸发和增加的密度和燃烧环的发射度量。两个耀斑峰处的冠状血浆温度达到54-55 mk。基于在这两个事件上施加的耀斑的温度和时间尺度的诊断使我们可以推断出5-7 x 10^10 cm的循环长度，这大约是恒星半径的大小。我们还推断出2.3-6.5 x 10^11 cm^-3的耀斑峰值的电子密度值，并限制等离子体所需的300-500 g的最小磁场强度。在耀斑期间释放的能量在0.3-10 keV的频带中为5-8 x 10^34 ERG，在紫外线（200-300 nm）中释放的0.9-2.7 x 10^33 ERG。我们推测，耀斑与冠状质量弹出（CME）相关，该冠状（CME）在耀斑后约3.3小时击中行星，并大大提高了行星的蒸发率。从RGS光谱中，我们检索了在静止状态和燃烧状态期间的排放测量分布和冠状金属的丰度。与时间分辨光谱和史诗光谱所推论的一致，也从耀斑期间的RGS光谱分析中推断出我们推断出高电子密度。
Abridged. We observed the 40 Myr old star DS Tuc A with XMM-Newton and recorded two X-ray bright flares, with the second event occurring about 12 ks after the first one. Their duration from the rise to the end of the decay was of about 8-10 ks in soft X-rays (0.3-10 keV). The flares were also recorded in the band 200-300 nm with the UVM2 filter of the Optical Monitor. The duration of the flares in UV was about 3 ks. The observed delay between the peak in the UV band and in X-rays is a probe of the heating phase followed by the evaporation and increase of density and emission measure of the flaring loop. The coronal plasma temperature at the two flare peaks reached 54-55 MK. The diagnostics based on temperatures and time scales of the flares applied to these two events allow us to infer a loop length of 5-7 x 10^10 cm, which is about the size of the stellar radius. We also infer values of electron density at the flare peaks of 2.3-6.5 x 10^11 cm^-3 , and a minimum magnetic field strength of order of 300-500 G needed to confine the plasma. The energy released during the flares was of order of 5-8 x 10^34 erg in the band 0.3-10 keV and 0.9-2.7 x 10^33 erg in the UV band (200-300 nm). We speculate that the flares were associated with Coronal Mass Ejections (CMEs) that hit the planet about 3.3 hr after the flares and dramatically increasing the rate of evaporation of the planet. From the RGS spectra we retrieved the emission measure distribution and the abundances of coronal metals during the quiescent and the flaring states. In agreement with what inferred from time resolved spectroscopy and EPIC spectra, also from the analysis of RGS spectra during the flares we infer a high electron density.
