论文标题

处女座集群中的年轻,蓝色和孤立的恒星系统。 ii。新的恒星系统

Young, blue, and isolated stellar systems in the Virgo Cluster. II. A new class of stellar system

论文作者

Jones, Michael G., Sand, David J., Bellazzini, Michele, Spekkens, Kristine, Karunakaran, Ananthan, Adams, Elizabeth A. K., Battaglia, Giuseppina, Beccari, Giacomo, Bennet, Paul, Cannon, John M., Cresci, Giovanni, Crnojevic, Denija, Caldwell, Nelson, Fuson, Jackson, Guhathakurta, Puragra, Haynes, Martha P., Inoue, John L., Magrini, Laura, Munoz, Ricardo R., Mutlu-Pakdil, Burcin, Seth, Anil, Strader, Jay, Toloba, Elisa, Zaritsky, Dennis

论文摘要

我们在处女座群集的方向上讨论了五个蓝色恒星系统,类似于神秘的对象Secco 1(AGC 226067)。这些对象是根据其光学和紫外线形态鉴定的,然后使用VLA(和GBT),Muse/VLT光谱和HST成像进行HI观察。这些新数据表明一个系统是遥远的星系组。 The remaining four are extremely low mass ($M_\ast \sim 10^5 \; \mathrm{M_\odot}$), are dominated by young, blue stars, have highly irregular and clumpy morphologies, are only a few kpc across, yet host an abundance of metal-rich, $12 + \log (\mathrm{O/H}) > 8.2$, HII regions.这些高金属性表明,这些恒星系统是由从更大的星系中剥离的气体形成的。尽管他们的出色人群年龄很小,但在HI中仅检测到一个系统,而其余三个系统的气体储层最少(如果有)。此外,两个系统令人惊讶地隔离,并且在$ \ sim $ 30'($ \ sim $ 140 kpc)之内没有合理的父级银河系。尽管潮汐剥离不能被最终排除为这些物体的形成机制,但RAM压力剥离更自然地解释了它们的性质,特别是由于相对于母体系统的较高速度,它们可以实现。因此,我们认为,这些系统中的大多数是由从新的插入群集成员中去除的RAM压力剥离的气体形成的,并且在群内培养基中存活了足够长的时间,以使其与母体星系相隔数百千座,因此它们代表了一种新型的恒星系统。

We discuss five blue stellar systems in the direction of the Virgo cluster, analogous to the enigmatic object SECCO 1 (AGC 226067). These objects were identified based on their optical and UV morphology and followed up with HI observations with the VLA (and GBT), MUSE/VLT optical spectroscopy, and HST imaging. These new data indicate that one system is a distant group of galaxies. The remaining four are extremely low mass ($M_\ast \sim 10^5 \; \mathrm{M_\odot}$), are dominated by young, blue stars, have highly irregular and clumpy morphologies, are only a few kpc across, yet host an abundance of metal-rich, $12 + \log (\mathrm{O/H}) > 8.2$, HII regions. These high metallicities indicate that these stellar systems formed from gas stripped from much more massive galaxies. Despite the young age of their stellar populations, only one system is detected in HI, while the remaining three have minimal (if any) gas reservoirs. Furthermore, two systems are surprisingly isolated and have no plausible parent galaxy within $\sim$30' ($\sim$140 kpc). Although tidal stripping cannot be conclusively excluded as the formation mechanism of these objects, ram pressure stripping more naturally explains their properties, in particular their isolation, owing to the higher velocities, relative to the parent system, that can be achieved. Therefore, we posit that most of these systems formed from ram pressure stripped gas removed from new infalling cluster members, and survived in the intracluster medium long enough to become separated from their parent galaxies by hundreds of kiloparsecs, and that they thus represent a new type of stellar system.

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