The halo of M 105 and its group environment as traced by planetary nebula populations
The halo of M 105 and its group environment as traced by planetary nebula populations
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M 105 的光环及其由行星状星云种群追踪的群体环境
DOI：
10.1051/0004-6361/202038009
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发表时间：
2020
影响因子：
6.5
通讯作者：
K. Kuijken
中科院分区：
文献类型：
--
作者：
J. Hartke;M. Arnaboldi;O. Gerhard;L. Coccato;C. Pulsoni;K. Freeman;M. Merrifield;A. Cortesi;K. Kuijken
语境。 M 105 (NGC 3379) 是狮子座 I 群中的一个早期型星系。 Leo I群是最近的群，包含所有主要星系类型，因此可以用作研究低质量群中群内光（IGL）特性的基准。
目标。我们对星系扩展晕中的行星状星云 (PNe) 进行了光度测量，以表征其 PN 群，并研究与群内光相关的扩展 PN 群的存在。
方法。我们使用 PNe 作为 M 105 周围漫射光的离散恒星示踪剂。这些 PNe 是根据其明亮的 [OIII]5007 Å 发射和使用自动检测技术不存在宽带连续谱来识别的。我们使用已发表的哈勃太空望远镜在两个晕场中的光度测量，将 PN 数密度分布与分解为金属丰度成分的星系表面亮度分布进行比较。
结果。我们从 Subaru-SuprimeCam 成像中识别出 m5007 极限星等内的 226 个 PNe 候选体， lim = 28.1，覆盖沿 M 105 主轴以及 NGC 3384 和 NGC 3398 光晕的 67.6 kpc（23 个有效半径）。与宽带的恒星表面亮度剖面相比，我们发现大半径处有过量的 PNe调查。这种过量与特定于光度的 PN 数 α 随半径的变化有关。扩展光环的α参数值比内光环高七倍以上。我们还测量了 PN 光度函数的斜率在较弱的幅度随半径的增加。
结论。我们推断，除了 M 105 晕之外，PN 星群特性的径向变化是由于遵循指数分布的贫金属恒星 ([M/H] < -1.0) 的扩散群所致。这些贫金属恒星的数密度分布与α参数值随半径的增加之间的空间重合建立了金属丰度和恒星演化的渐近后巨分支阶段之间缺失的联系。我们估计与指数 IGL 群体相关的总辐射热光度的下限为 2.04 × 109 L⊙。因此，IGL 分数的下限为 3.8%。这项工作为低质量群体中 IGL 的运动学研究奠定了基础。
Context. M 105 (NGC 3379) is an early-type galaxy in the Leo I group. The Leo I group is the nearest group that contains all main galaxy types and can thus be used as a benchmark to study the properties of the intra-group light (IGL) in low-mass groups.
Aims. We present a photometric survey of planetary nebulae (PNe) in the extended halo of the galaxy to characterise its PN populations and investigate the presence of an extended PN population associated with the intra-group light.
Methods. We use PNe as discrete stellar tracers of the diffuse light around M 105. These PNe were identified on the basis of their bright [O III]5007 Å emission and the absence of a broad-band continuum using automated detection techniques. We compare the PN number density profile with the galaxy surface-brightness profile decomposed into metallicity components using published photometry of the Hubble Space Telescope in two halo fields.
Results. We identify 226 PNe candidates within a limiting magnitude of m5007, lim = 28.1 from our Subaru-SuprimeCam imaging, covering 67.6 kpc (23 effective radii) along the major axis of M 105 and the halos of NGC 3384 and NGC 3398. We find an excess of PNe at large radii compared to the stellar surface brightness profile from broad-band surveys. This excess is related to a variation in the luminosity-specific PN number α with radius. The α-parameter value of the extended halo is more than seven times higher than that of the inner halo. We also measure an increase in the slope of the PN luminosity function at fainter magnitudes with radius.
Conclusions. We infer that the radial variation of the PN population properties is due to a diffuse population of metal-poor stars ([M/H] < −1.0) following an exponential profile, in addition to the M 105 halo. The spatial coincidence between the number density profile of these metal-poor stars and the increase in the α-parameter value with radius establishes the missing link between metallicity and the post-asymptotic giant branch phases of stellar evolution. We estimate that the total bolometric luminosity associated with the exponential IGL population is 2.04 × 109 L⊙ as a lower limit. The lower limit on the IGL fraction is thus 3.8%. This work sets the stage for kinematic studies of the IGL in low-mass groups.