Infrared Monitor Observations of T-Tauri Stars

该项目的最终目标是通过红外波段的监测观测，找出金牛座T星亮度随时间变化的原因。据推测，其起源与金牛座t星的表面活动以及光球与盘之间接触区域的活动有关。红外监测观测在面积和时间间隔上仍然非常有限。我们准备了红外相机和小型望远镜，使我们能够使用大约0.3平方弧度的相当宽的视场，实现高效的观测。该系统还具有在单一视场内观测几颗金牛座T星以及通量标准星（第二校准器）的能力。该系统的灵敏度在曝光20分钟时信噪比为10，在J波段为17等，在H波段为15.5等，在K波段为14等，其深度足以观测金牛座恒星形成区（距我们140pc）的金牛座T星。为了开发相机部分，我们首先对astrof任务红外相机的测试模型InSb红外阵列进行了评估。我们在小叶校区采用液氦冷却室操作传感器装置、COGITO-3多控制系统操作探测器和32cm牛顿望远镜进行了评估。为了在红外波段获得较宽的视场，还研制了最小化彗差的光学元件。我们对金牛座T星进行了监测观测，并利用ASTRO-F扩展了对恒星形成区域的预测观测。

The ultimate goal of this project is to find out the origin of time variation of brightness of T Tauri stars by monitor observations at infrared wavelength. The origin is supposed to associate with the surface activities of T-Tauri star as well as activity at the contact region between the photosphere and the disk. Infrared monitor observations are still very limited in area as well as the time intervals.We prepared infrared camera and small telescope, which enable us to use rather wide field of view covering approximately 0.3 square degree of arc, to realize efficient observations. The system also has capability to observe several T Tauri stars as well as flux standard stars (second calibrators) in a single field of view. The sensitivities of the system, with 10 of signal-to-noise ratio at 20 minutes of exposure, are 17 magnitude at J band, 15.5 magnitude at H band, and 14 magnitude at K' band, whose depth is enough to observe T Tauri stars in Taurus star forming regions (lying at 140pc from us). To develop the camera part, we first started evaluation of InSb infrared array which is a test model of the infrared camera on board ASTRO-F mission. We carried out the evaluations using liquid He cooled chamber to operate the sensor device, COGITO-3 multi control system to operate the detector, and 32 cm Newtonian telescope in Komaba campus. The optics to minimize the Coma aberration was also developed to get a wide field of view at infrared wavelength. We have made monitor observations of T Tauri stars and been extending the projected observations of star forming regions with ASTRO-F.