過去幾十年，古柏帶的矮行星對我們而言過於遙遠，以致於無法透過地面望遠鏡或太空望遠鏡進行詳細的觀測研究。而NASA的新視野號於2015年7月飛越冥王星系統，使我們對這些遙遠的物體有更多了解。透過新視野號近距離的飛掠觀測，發現冥王星上的大型心型地區—湯博區。湯博區是此次太空任務最重要的發現之一，它位於冥王星北半球的赤道至中緯地區，與冥衛一凱倫處於潮汐鎖定的對位。史波尼克高原位於湯博區的左半邊，為冥王星最高反照率的冰層地形，觀測資料顯示該地區主要是由氮冰及其他種類，如：甲烷、碳氫化合物的冰塊凝結而成。除此之外，冥王星的大氣組成在這次的觀測任務中被精確地觀測，稀薄的大氣層主成分為氮氣及少量的二氧化碳。由上述兩項結果推論，冥王星的大氣變化很可能是由史波尼克高原上的氮冰所控制。 在這份研究中，我們建立季節演化的熱模型，計算史波尼克高原在偏心軌道上圍繞太陽公轉時，氮冰的昇華過程與熱傳導效應造成的表面溫度與大氣壓力變化。這套模型能夠探索冰冷矮行星的大氣含量與質量損失過程，另外，我們會將這個模型應用於古柏帶中其他成分組成類似冥王星的矮行星。 ;Dwarf planets in Kuiper belt are too far for us to study in detail by telescopic observations from Earth for past several decades. After the New Horizons spacecraft’s flyby observations of the Pluto-Charon system in July 2015, we now have a better understanding of these faraway objects. The Sputnik Planitia of Pluto is one of the most important discoveries of the New Horizons spacecraft at its flyby observations of the Pluto-Charon system in July 2015. SP is located at the northern mid-latitude hemisphere in the antipodal position to Charon on the opposite side. It contains a large quantity of the nitrogen ice on Pluto and the content of Pluto’s atmosphere is likely controlled by the variable sublimation rate of the Sputnik Planitia’s ice. In this work, we use a coupled treatment to compute the surface temperature and pressure of the Sputnik Planitia on Pluto when it revolves around the sun in its eccentric orbit with special attention to the sublimation process of the nitrogen ice stored in the Sputnik Planitia. In addition, we will apply this model to other Pluto-like dwarf planets in Kuiper belt which surfaces could be mainly composed of nitrogen ice. This set of model calculations allows us to explore the range of the atmospheric contents and mass loss process of the icy dwarf planets.
