Looking for Obscured Young Star Clusters in NGC 1313
Looking for Obscured Young Star Clusters in NGC 1313
复制标题
DOI：
10.3847/1538-4357/abe0b5
复制
发表时间：
2020-11
期刊：
影响因子：
--
通讯作者：
M. Messa;D. Calzetti;A. Adamo;K. Grasha;Kelsey E. Johnson;E. Sabbi;Linda J. Smith;V. Bajaj
中科院分区：
文献类型：
--
作者：
M. Messa;D. Calzetti;A. Adamo;K. Grasha;Kelsey E. Johnson;E. Sabbi;Linda J. Smith;V. Bajaj
利用最近获得的哈勃空间望远镜近红外观测（J，Pa β和H波段）的附近星系NGC 1313，我们调查所需的时间尺度的年轻星星集群从出生云。我们寻找可能嵌入其诞生云中的致密星星团，它们可能是（1）高H α/Pa β发射率区域中的致密源，或（2）致密H ii区域，在Pa β发射图中显示为点状源。通过最小-χ 2光谱能量分布的宽、窄带拟合过程，利用候选星系团的NUV-光学-NIR测光，得到了它们的年龄、质量和光度。最终样本中的100个星团的质量在范围内，中等偏高，E（B-V）<$1.0马格。专注于年轻的星团（0 - 6百万年），我们得出了一个弱的灭绝和年龄之间的相关性集群。几乎有一半的星团在非常年轻的时候（≤ 300万年）就有低的折射率，E（B − V）<0.25等，这表明尘埃很快就从星团中被清除了。星云发射的形态（致密、部分或不存在，在H α和Pa β中都有）与星团年龄之间有较强的相关性。与特定的星云形态相关联的星团的相对分数被用来估计清除出生气云的典型时间尺度，导致在300万和500万之间，比基于NUV光学的星团研究估计的要老100万。这种差异暗示了仅基于光学的研究的偏见，詹姆斯韦伯太空望远镜将在未来几年解决这个问题。
Using recently acquired Hubble Space Telescope NIR observations (J, Paβ, and H bands) of the nearby galaxy NGC 1313, we investigate the timescales required by a young star cluster to emerge from its natal cloud. We search for extincted star clusters, potentially embedded in their natal cloud as either (1) compact sources in regions with high Hα/Paβ extinctions or (2) compact H ii regions that appear as point-like sources in the Paβ emission map. The NUV–optical–NIR photometry of the candidate clusters is used to derive their ages, masses, and extinctions via a least-χ 2 spectral energy distribution broad- and narrowband fitting process. The 100 clusters in the final samples have masses in the range and moderate extinctions, E(B − V) ≲ 1.0 mag. Focusing on the young clusters (0–6 Myr), we derive a weak correlation between extinction and age of the clusters. Almost half of the clusters have low extinctions, E(B − V) < 0.25 mag, already at very young ages (≤3 Myr), suggesting that dust is quickly removed from clusters. A stronger correlation is found between the morphology of the nebular emission (compact, partial or absent, both in Hα and Paβ) and cluster age. Relative fractions of clusters associated with a specific nebular morphology are used to estimate the typical timescales for clearing the natal gas cloud, resulting in between 3 and 5 Myr, ∼1 Myr older than what was estimated from NUV–optical-based cluster studies. This difference hints at a bias for optical-only-based studies, which James Webb Space Telescope will address in the coming years.