We have reanalyzed the ultraviolet spectrum of HD 44179, the central star(s) of the Red Rectangle Nebula, providing improved estimates of the column density, rotational, and vibrational temperatures of the 4th Positive A-X system of CO in absorption. The flux shortward of 2200 A is a complex blend of CO features with no discernible stellar photosphere, making the identification of other molecular species difficult, and the direct derivation of the dust extinction curve impossible. We confirm that the spin-forbidden CO(a-X) Cameron bands are likely produced by either collisional excitation or a chemical reaction, not photoexcitation, but with a higher internal vibrational excitation than previously determined. We also detect the spin-forbidden CO a'-X, d-X, and e-X absorption features. The hot CO(A-X) bands exhibit a blueshift of ～300 km s~(-1) likely occurring close to the white dwarf star(s) suspected as the original source of the ultraviolet flux in the system, and forming the base of the outflow of material in the Red Rectangle. The OH "comet-band" system near 3000 A is also analyzed, and estimates of its rovibrational temperatures determined. The source of the molecules studied in this system is still unknown, but may be a combination of gaseous material associated with the star(s), or processed material from the surrounding dust torus.
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机译：我们对红色矩形星云的中心恒星HD 44179的紫外光谱进行了重新分析，从而提供了对第4个正CO吸收的A-X正系统的柱密度，旋转和振动温度的改进估算。 2200 A的通量不足是CO特征的复杂混合，没有可辨认的恒星光球，这使其他分子种类的鉴定变得困难，并且无法直接推导消光曲线。我们确认，自旋禁止的CO（a-X）Cameron带很可能是通过碰撞激发或化学反应而非光激发产生的，但其内部振动激发比先前确定的要高。我们还检测了自旋禁止的CO a'-X，d-X和e-X吸收特征。高温的CO（AX）波段表现出约300 km s〜（-1）的蓝移，该蓝移很可能发生在靠近被认为是系统紫外线通量的原始来源的白矮星附近，并形成了系统的基础。红色矩形中的材料流出。还分析了3000 A附近的OH“彗带”系统，并确定了其旋转温度的估计值。在该系统中研究的分子的来源仍是未知的，但可能是与恒星相关的气态物质或来自周围尘埃圆环的加工物质的组合。
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