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arXiv 1905.02468astro-ph.GAastro-ph.CO
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揭示矮星系NGC 185中中心发射星云的性质

Revealing the nature of central emission nebulae in the dwarf galaxy NGC 185

M. M. Vučetić, D. Ilić, O. V. Egorov, A. Moiseev, D. Onić, T. G. Pannuti, B. Arbutina, N. Petrov, D. Urošević

摘要:

在本文中,我们提出了新的光学观测星系NGC 185旨在揭示超新星遗迹(SNRs)在这个矮伴星的仙女座星系的地位。此前,据报道,该星系拥有一个SNR。我们使用罗真国家天文台的2米望远镜,使用窄带H $α$和[SII]滤光片进行了深度测光研究,揭示了星系中心星际介质的复杂结构。为了确认分类并研究所探测到的星云的运动学,我们在俄罗斯科学院特殊天体物理观测台的6米望远镜上使用SCORPIO多模式摄谱仪进行了低分辨率和高分辨率模式的光谱观测。我们还搜索了存档的X射线和无线电数据,以寻找我们的光学观测所确定的候选SNR的对应物。我们的观察意味着存在一个更多的SNR,一个可能的HII区域先前编目的SNR的一部分,并在一个低亮度PN的冲击电离的额外来源的存在。我们检测到增强的[SII]/H_alpha和[NII]/H_alpha线比,以及相对较高的(高达90 km/s $^{-1}$)的膨胀速度的两个观测星云,激发其分类为信噪比(直径为45 pc和50 pc),证实了光度和光谱观测。发射星云的电子密度估计为30 - 200 cm $^{-3}$。存档的XMM-牛顿观测表明,在其中一个光学SNR的投影中存在一个扩展的,低亮度的软源,而存档的VLA无线电图像显示NGC 185中心的微弱,未解析的发射。

英文摘要:

In this paper we present new optical observations of the galaxy NGC 185 intended to reveal the status of supernova remnants (SNRs) in this dwarf companion of the Andromeda galaxy. Previously, it was reported that this galaxy hosts one SNR. Our deep photometric study with the 2m telescope at Rozhen National Astronomical Observatory using narrow-band H$α$ and [SII] filters revealed complex structure of the interstellar medium in the center of the galaxy. To confirm the classification and to study the kinematics of the detected nebulae, we carried out spectroscopic observations using the SCORPIO multi-mode spectrograph at the 6m telescope at the Special Astrophysical Observatory of the Russian Academy of Science, both in low- and high-resolution modes. We also searched the archival X-ray and radio data for counterparts of the candidate SNRs identified by our optical observations. Our observations imply the presence of one more SNR, one possible HII region previously cataloged as part of an SNR, and the presence of an additional source of shock ionization in one low-brightness PN. We detected enhanced [SII]/H_alpha and [NII]/H_alpha line ratios, as well as relatively high (up to 90 km s$^{-1}$) expansion velocities of the two observed nebulae, motivating their classification as SNRs (with diameters of 45 pc and 50 pc), confirmed by both photometric and spectral observations. The estimated electron density of emission nebulae is 30 - 200 cm$^{-3}$. Archival XMM-Newton observations indicate the presence of an extended, low-brightness, soft source in projection of one of the optical SNRs, whereas the archival VLA radio image shows weak, unresolved emission in the center of NGC 185.

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