V496 Scuti：一颗Fe II新星，尘埃壳伴随CO发射
V496 Scuti: An Fe II nova with dust shell accompanied by CO emission
摘要：
我们目前的近红外和光学观测的新星V496 Scuti 2009涵盖了不同的阶段-前极大，早期衰退和星云-在其发现的前10个月，其次是有限的观测在2011年4月的早期。光谱遵循演化的新星时，线有很强的P天鹅座配置文件的一个阶段占主导地位的突出的发射线。在下降初期的近红外光谱的显着特点是一氧化碳的第一泛音带的发射中的罕见的存在。在亮度达到峰值后约150天，红外光谱显示在膨胀的喷出物中有清晰的尘埃形成。在V496 Sct的尘埃形成是一致的存在的低电离势的元素，如钠和镁在早期的光谱和CO带的检测发射。光变曲线显示缓慢上升到最大值和缓慢下降，表明质量损失延长。这是证实了加强的天鹅座P剖面在第一个30天。在接近光学最大亮度的光谱中，发现时看到的宽而单一的吸收成分被两个更尖锐的成分所取代。在早期的下降阶段，两个急剧下降，表明增加流出速度被认为是在天鹅座P的Fe II和H I线的吸收组件。2010年3月的光谱显示星云相的开始。几条发射线显示鞍状轮廓在星云阶段。在星云阶段，观测到的[O III]和H-β线的流量被用来估计电子数密度和喷出物的质量。光谱分析表明，该新星是按P_feA_o光谱序列演化的。对喷出物的物理条件进行了估计。其绝对星等为M_V = -7.0 +/-0.2，d = 2.9 +/-0.3kpc。
英文摘要：
We present near-infrared and optical observations of the nova V496 Scuti 2009 covering various phases - pre-maximum, early decline and nebular - during the first 10 months of its discovery followed by limited observations in early part of 2011 April. The spectra follow the evolution of the nova when the lines had strong P Cygni profiles to a phase dominated by prominent emission lines. The notable feature of the near-IR spectra in the early decline phase is the rare presence of first overtone bands of carbon monoxide in emission. Later about 150 days after the peak brightness the IR spectra show clear dust formation in the expanding ejecta. Dust formation in V496 Sct is consistent with the presence of lines of elements with low ionization potentials like Na and Mg in the early spectra and the detection of CO bands in emission. The light curve shows a slow rise to the maximum and a slow decline indicating a prolonged mass loss. This is corroborated by the strengthening of P Cygni profiles during the first 30 days. In the spectra taken close to the optical maximum brightness, the broad and single absorption component seen at the time of discovery is replaced by two sharper components. During the early decline phase two sharp dips that show increasing outflow velocities are seen in the P Cygni absorption components of Fe II and H I lines. The spectra in 2010 March showed the onset of the nebular phase. Several emission lines display saddle-like profiles during the nebular phase. In the nebular stage the observed fluxes of [O III] and H-beta lines are used to estimate the electron number densities and the mass of the ejecta. The optical spectra show that the nova evolved in the P_fe A_o spectral sequence. The physical conditions in the ejecta are estimated. The absolute magnitude and the distance to the nova are estimated to be M_V = -7.0 +/- 0.2 and d = 2.9 +/- 0.3 kpc respectively.
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