We report on $UBVI$ photometry and spectroscopy for MK classification purposes carried out in the fields of five open clusters projected against the Vela Gum in the Third Galactic Quadrant of the Galaxy. They are Ruprecht 20, Ruprecht 47, Ruprecht 60, NGC 2660 and NGC 2910. We could improve/confirm the parameters of these objects derived before. The spectroscopic parallax method has been applied to several stars located in the fields of four out of the five clusters to get their distances and reddenings. With this method we found two blue stars in the field of NGC 2910 at distances that make them likely members of Vela OB1 too. Also, projected against the fields of Ruprecht 20 and Ruprecht 47 we have detected other young stars favoring not only the existence of Puppis OB1 and OB2 but conforming a young stellar group at $\sim1$ kpc from the Sun and extending for more than 6 kpc outward the Galaxy. If this is the case, there is a thickening of the thin Galactic disk of more than 300 pc at just 2-3 kpc from the Sun. Ruprecht 60 and NGC 2660 are too old objects that have no physical relation with the associations under discussion. An astonishing result has been the detection in the background of Ruprecht 47 of a young star at the impressive distance of 9.5 kpc from the Sun that could be a member of the innermost part of the Outer Arm. Another far young star in the field of NGC 2660, at near 6.0 kpc, may become a probable member of the Perseus Arm or of the inner part of the Local Arm. The distribution of young clusters and stars onto the Third Galactic Quadrant agrees with recent findings concerning the extension of the Local Arm as revealed by parallaxes of regions of star formation. We show evidences too that added to previous ones found by our group explain the thickening of the thin disk as a combination of flare and warp.
Low-frequency spectra and scattering of pulsars towards the Gum Nebula with the MWA
Shanghai Astronomical Observatory, Chinese Academy of Sciences（中国科学院上海天文台）；School of Astronomy and Space Science, University of Chinese Academy of Sciences（中国科学院大学天文与空间科学学院）；State Key Laboratory of Radio Astronomy and Technology, Xinjiang Astronomical Observatory, Chinese Academy of Sciences（中国科学院新疆天文台射电天文与技术重点实验室）；National Astronomical Observatories, Chinese Academy of Sciences（中国科学院国家天文台）
Substellar population of the young massive cluster RCW 36 in Vela
Universidade de Lisboa（里斯本大学）；Université de Bordeaux（波尔多大学）；Institut universitaire de France (IUF)（法国高等教育研究院）；NSF NOIRLab/Vera C. Rubin Observatory（美国国家科学基金会NOIRLab/维拉·C·鲁宾天文台）；Istituto Nazionale di Astrofisica (INAF) – Osservatorio Astronomico di Palermo（意大利国家天体物理研究所巴勒莫天文台）；European Southern Observatory（欧洲南方天文台）；University of St Andrews（圣安德鲁斯大学）；Stockholm University（斯德哥尔摩大学）；American Museum of Natural History（美国自然历史博物馆）；Universidad Diego Portales（迭戈·波特莱斯大学）；Millennium Nucleus on Young Exoplanets and their Moons (YEMS)（年轻系外行星及其卫星千年核心）；Canada-France-Hawaii Telescope Corporation（加拿大-法国-夏威夷望远镜公司）；Instituto de Astrofísica de Andalucía (CSIC)（安达卢西亚天体物理研究所）
该研究通过分析 RCW 36 星团的 IMF 和恒星-褐矮星比值，揭示了其亚恒星群体的分布特征及可能的原始质子分离现象。
