The Serpens Molecular Cloud is one of the most active sites of ongoing star formation at a distance of about 300 pc, and hence is very well-suited for studies of young low-mass stars and sub-stellar objects. In this paper, for the Serpens star forming region, we find potential members of the Young Stellar Objects population from the Gaia DR3 data and study their kinematics and distribution. We compile a catalog of 656 YSOs from available catalogs ranging from X-ray to the infrared. We use this as a reference set and cross-match it to find 87 Gaia DR3 member stars to produce a control sample with revised parameters. We queried the DR3 catalog with these parameters and found 1196 stars. We then applied three different density-based machine learning algorithms (DBSCAN, OPTICS and HDBSCAN) to this sample and found potential YSOs. The three clustering algorithms identified a common set of 822 YSO members from Gaia DR3 in this region. We also classified these objects using 2MASS and WISE data to study their distribution and the progress of star formation in Serpens.
Active star forming regions are excellent laboratories for studying the origins and evolution of young stellar object (YSO) clustering. The W40 - Serpens South region is such a region, and we compile a super near-and-mid-infrared catalog of point sources in it, based on deep NIR observations of CFHT in combination with 2MASS, UKIDSS, and Spitzer catalogs. From this catalog, we identify 832 YSOs, and classify 15, 135, 647, and 35 of them to be the deeply embedded sources, Class I, Class II YSOs, and transition disk sources, respectively. In general, these YSOs are well correlated with the filam…
Young stellar clusters are believed to inherit the spatial distribution like hierarchical structures of their natal molecular cloud during their formation. However, the change of the structures between the cloud and the young clusters is not well constrained observationally. We select the W40 - Serpens South region (~ 7 $\times$ 9 pc$^{2}$) of the Aquila Rift as a testbed and investigate hierarchical properties of spatial distribution of young stellar objects (YSOs) in this region. We develop a minimum spanning tree (MST)-based method to group stars into several levels by successively cutting …
The Serpens Molecular Cloud is one of the most active star-forming regions within 500 pc, with over one thousand of YSOs at different evolutionary stages. The ages of the member stars inform us about the star formation history of the cloud. In this paper, we develop a spectral energy distribution (SED) fitting method for nearby evolved (diskless) young stars from members of the Pleiades to estimate their ages, with a temperature scale adopted from APOGEE spectra. When compared with literature temperatures of selected YSOs in Orion, the SED fits to cool (<5000 K) stars have temperatures that di…
We present Gaia-DR2 astrometry of a sample of YSO candidates in Ophiuchus, Serpens Main and Serpens South/W40 in the Aquila Rift, which had been mainly identified by their infrared excess with Spitzer. We compare the Gaia-DR2 parallaxes against published and new parallaxes obtained from our Very Long Baseline Array (VLBA) program GOBELINS. We obtain consistent results between Gaia and the VLBA for the mean parallaxes in each of the regions analyzed here. We see small offsets, when comparing mean values, of a few tens of micro-arcseconds in the parallaxes, which are either introduced by the Gai…
Star formation is known to occur more readily where more raw materials are available. This is often expressed by a 'Kennicutt-Schmidt' relation where the surface density of Young Stellar Objects (YSOs) is proportional to column density to some power, $μ$. The aim of this work was to determine if column density alone is sufficient to explain the locations of Class 0/I YSOs within Serpens South, Serpens Core, Ophiuchus, NGC1333 and IC348, or if there is clumping or avoidance that would point to additional influences on the star formation. Using the O-ring test as a summary statistic, 95 per cent…
Mapping Active Star-Formation in Serpens and the Aquila Rift
University of Alaska Anchorage（阿拉斯加安克雷奇大学）；Dunlap Institute for Astronomy & Astrophysics, University of Toronto（多伦多大学邓普天文学与天体物理研究所）；Northern Arizona University（北亚利桑那大学）；Space Science Institute（空间科学研究所）；Steward Observatory, University of Arizona（亚利桑那大学斯图尔德天文台）；University of Toronto Mississauga（多伦多大学密西沙加分校）
We present Herschel Space Observatory Photodetector Array Camera and Spectrometer (PACS) and Spectral and Photometric Imaging Receiver Fourier Transform Spectrometer (SPIRE FTS) spectroscopy of a sample of twenty massive Young Stellar Objects (YSOs) in the Large and Small Magellanic Clouds (LMC and SMC). We analyse the brightest far infrared (far-IR) emission lines, that diagnose the conditions of the heated gas in the YSO envelope and pinpoint their physical origin.We compare the properties of massive Magellanic and Galactic YSOs.We find that [OI] and [CII] emission, that originates from the …
The fastest molecular component to the protostellar outflows -- extremely high-velocity (EHV) molecular jets -- are still puzzling since they are seen only rarely. The first aim is to analyze the interaction between the EHV jet and the slow outflow by comparing their outflow force content. The second aim is to analyze the chemical composition of the different outflow velocity components and to reveal the spatial location of molecules. ALMA 3 mm and 1.3 mm observations of five outflow sources at 130 -- 260 au resolution in the Serpens Main cloud are presented. Observations of CO, SiO, H$_2$CO a…
Accurate measurements of statistical properties, such as the star formation rate and the lifetime of young stellar objects (YSOs) in different stages, is essential for constraining star formation theories. However, it is a difficult task to separate galaxies and YSOs based on spectral energy distributions (SEDs) alone, because they contain both thermal emission from stars and dust around them and no reliable theories can be applied to distinguish them. Here we compare different machine learning algorithms and develop the Spectrum Classifier of Astronomical Objects (SCAO), based on Fully Connec…
JWST Reveals Star Formation Across a Spiral Arm in M33
University of Alberta（阿尔伯塔大学）；University of Oxford（牛津大学）；Harvard & Smithsonian（哈佛-史密森天体物理中心）；Raytheon（雷神公司）；Steward Observatory, University of Arizona（亚利桑那大学斯图尔德天文台）；Universiteit Gent（根特大学）；University of Washington（华盛顿大学）；Flatiron Institute（平顿研究所）；University of Florida（佛罗里达大学）；Northwestern University（西北大学）；The Ohio State University（俄亥俄州立大学）
Exploring Young Stellar Variability with Gaia DR3 light curves
University of Geneva（日内瓦大学）；Konkoly Observatory, Research Centre for Astronomy and Earth Sciences, Hungarian Research Network (HUN-REN)（孔科利天文台，匈牙利研究网络（HUN-REN）地球科学研究中心）；CSFK, MTA Centre of Excellence（CSFK，马塔卓越中心）；University of Szeged（塞格德大学）；Universität Wien（维也纳大学）；Natural History Museum Vienna（维也纳自然史博物馆）
Star Formation and Young Population of the HII Complex Sh2-294
Sh 2 -294的HII区被一颗B 0 V恒星电离，其特征是有几个红外线过剩源，一个光解离区，以及一组在其边界的变红恒星。该地区的恒星形成情况似乎相当复杂。在本文中，我们提出了后续的结果，在3.6，4.5，5.8，和8.0微米观察斯皮策太空望远镜红外阵列相机（IRAC），再加上H2（2.12微米）的观察，以描述该地区的年轻人口，并了解其恒星形成的历史。我们确定了36个年轻的恒星对象（YSO，I类，II类和I/II类）的候选人使用IRAC颜色-颜色图。据发现，I类源优先位于HII区域的外围，并与增强的H2排放;没有一个位于中心集群附近。结合YSO候选星的光学-中红外测光，利用光谱能量分布拟合模型，对33颗YSO候选星的恒星参数和演化状态进行了约束。其中大多数被模型解释为低质量（< 4个太阳质量）的YSO;然而，我们也探测到了一个大质量的I类YSO（~9个太阳质量），嵌入在~24 mag. Present分析表明，I类源相对于II类源（年龄~ 4.5 x 10^6年）确实是该地区较年轻的群体。我们认为，包括大质量YSO在内的大多数I类源都是该区域的第二代恒星，其形成可能是由一颗约4 x 10^6年的B 0主序星驱动的HII区域的膨胀引起的。
The aim of this study is to characterize the distribution and basic properties of the natal gas associated with high-mass young stellar objects (YSOs) in isolated environments in the Large Magellanic Cloud (LMC). High-mass stars usually form in Giant Molecular Clouds (GMCs) as part of a young stellar cluster, but some OB stars are observed far from GMCs. By examining the spatial coincidence between the high-mass YSOs and 12CO (J = 1-0) emission detected by NANTEN and Mopra observations, we selected ten high-mass YSOs that are located away from any of the NANTEN clouds but are detected by the M…
Copious star formation occurs in the dense Central Molecular Zone (CMZ) of our Galaxy, but at a much smaller rate than occurs in a comparable mass of molecular gas in the Galactic disk. The combination of large turbulent velocity dispersions, a relatively strong magnetic field, and a strong tidal field all contribute to inhibiting star formation (SF) in different ways in different CMZ locations. Nonetheless, there are spectacular displays of recent and ongoing SF in the CMZ, including massive young stellar clusters, sites of abundant SF in progress, and numerous spots of protostellar or YSO ac…
Feedback-Driven Interaction of Expanding Molecular Clouds in the LDN 1204-Sh2 145-Sh2 140 Complex
Aryabhatta Research Institute of Observational Sciences (ARIES)（阿里亚哈塔观测科学研究所以）；Department of Applied Physics, Mahatma Jyotiba Phule Rohilkhand University（马哈拉贾约提巴普尔罗希勒坎德大学应用物理系）；Astronomy & Astrophysics Division, Physical Research Laboratory（物理研究实验室天体物理学与天文学部）；Department of Applied Physics/Physics, Bareilly College（贝莱利学院应用物理/物理系）
We investigate at a high angular resolution the spatial and kinematic structure of the S255IR high mass star-forming region, which demonstrated recently the first disk-mediated accretion burst in the massive young stellar object. The observations were performed with ALMA in Band 7 at an angular resolution $ \sim 0.1^{\prime\prime}$, which corresponds to $ \sim 180 $ AU. The 0.9 mm continuum, C$^{34}$S(7-6) and CCH $N=4-3$ data show a presence of very narrow ($ \sim 1000 $ AU), very dense ($n\sim 10^7$ cm$^{-3}$) and warm filamentary structures in this area. At least some of them represent appa…
