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Target RA (J2000): 219.848709 and deg Target Dec (J2000): -60.82949 and deg Gaia GMag: 0 Programme ID: CH_PR140064 Programme Manager: VANGROOTEL PI of observing programme: Benz Title of programme: Axis 1 - Is there a transiting planet around Alpha Centauri? (ALPHACEN) Abstract: Alpha Centauri is the third brightest star in the night sky and the closest stellar system to us. It is composed of two stars similar to the Sun Alpha Cen A and B and a more distant but gravitationally bound red dwarf Proxima (the actual closest star to the Sun). In 2012 Dumusque et al. (Nature 491 207) announced from RV measurements a planet orbiting Alpha Cen B but its existence is still under debate. In 2015 Demory et al. (MNRAS 450 2043) found in highly-saturated Hubble Space Telescope observations of Alpha Cen B a single transit-like event ~95 ppm deep and ~3.6 h long. A likely explanation is an Earth-sized planet with an orbital period shorter than 20 days (the median of the likely orbits is 12.4 d). With this program we aim to observe Alpha Cen with CHEOPS in order to try to recover the transit seen by Demory et al. (2015). More generally CHEOPS observations will allow us to place strong constraints on the presence of close-in transiting planets around Alpha Cen which is a very valuable objective on its own and complementary to the current efforts for direct imaging of farther planets around Alpha Cen (Kasper et al. 2019 The Messenger 178 5). [truncated! Please see actual data for full text]

目标赤经（J2000坐标系）：219.848709度
目标赤纬（J2000坐标系）：-60.82949度
Gaia G星等：0
项目ID：CH_PR140064
项目主管：VANGROOTEL
观测项目首席研究员：Benz
项目标题：Axis1 - 半人马座α周围是否存在凌星行星？（ALPHACEN）
摘要：半人马座α是夜空中第三亮的恒星，也是距离我们最近的恒星系统。它由两颗与太阳相似的恒星（半人马座αA和B）以及一颗距离更远但受引力束缚的红矮星Proxima（实际上是距离太阳最近的恒星）组成。2012年，Dumusque等人（《自然》491卷207页）通过视向速度（RV）测量宣布发现了一颗环绕半人马座αB运行的行星，但其存在性仍存争议。2015年，Demory等人（《皇家天文学会月刊》450卷2043页）在哈勃空间望远镜对半人马座αB的高饱和观测中，发现了一次深度约95 ppm、时长约3.6小时的单次类凌星事件。一个可能的解释是存在一颗地球大小的行星，其轨道周期短于20天（可能轨道的中值为12.4天）。本项目旨在利用CHEOPS观测半人马座α，以尝试重现Demory等人（2015）观测到的凌星事件。更广泛地说，CHEOPS观测将使我们能够对半人马座α周围近距凌星行星的存在性施加严格限制，这本身就是一个极具价值的目标，同时也补充了当前对半人马座α周围更远行星进行直接成像的努力（Kasper等人，2019年《信使》178卷5页）。[内容截断！完整文本请参见实际数据]