Search for sub-stellar companions of T-Tauri stars in the Lupus star-forming region

在狼疮恒星形成区寻找 T-Tauri 恒星的亚恒星伴星

• 批准号: 202424241
• 负责人: Dr. Markus Mugrauer
• 金额: --
• 依托单位: Astrophysikalisches Institut und Universitätssternwarte
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2011
• 资助国家: 德国
• 起止时间: 2010-12-31 至 2014-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/202424241?language=en
• 关键词: Search; sub; stellar; companions; Tauri

So far, many exoplanets could already be detected indirectly on close (a < 6AU) orbits around mainly old main-sequence stars. Some brown dwarf companions were found on very wide (a > 100AU) orbits around young nearby stars by direct imaging, but very few such objects were imaged at intermediate separations between 10 up to tens of AU, up to now. We have started a high contrast imaging search campaign with NACO at ESO-VLT to directly detect such sub-stellar companions (brown dwarfs and giant planets) around young stars, not yet observed with NACO. Our target sample is chosen to maximize the detection rate, namely a few million years old T-Tauri stars in the nearby Lupus star-forming region. Because of the young age of our targets also their sub-stellar companions are young and hence self-luminous due to still ongoing contraction and accretion. We use NACO in its cube-mode to image such objects near the diffraction limit of the ESO-VLT and at larger separations. In May 2010, all our 63 targets were observed already in 1st epoch and faint sub-stellar companion-candidates were found around 58 stars with projected separations down to 21 AU. 2nd epoch follow-up imaging with NACO is scheduled in June 2011 to test the companionship of all detected candidates with astrometry. Afterwards, the sub-stellar nature of identified co-moving companions will be confirmed with follow-up photometry and spectroscopy (2012), which finally will allow us to derive the physical properties of these objects, like their effective temperatures, surface gravities, radii, and masses. Then, we can conduct a statistical test of the existence of the brown dwarf desert also at separations between ~10 and tens of AU. We will then also compare our results in Lupus with those of all other star-forming regions and associations observed previously like TWA, or Cha.

到目前为止，许多系外行星已经可以在主要围绕老主序恒星的近距离（a < 6AU）轨道上被间接探测到。通过直接成像，我们在围绕年轻邻近恒星的非常宽（a > 100AU）的轨道上发现了一些棕矮星伴星，但到目前为止，很少有这样的物体以 10 到数十个 AU 之间的中间间隔成像。我们已经与 NACO 在 ESO-VLT 启动了一项高对比度成像搜索活动，以直接探测 NACO 尚未观测到的年轻恒星周围的此类亚恒星伴星（褐矮星和巨行星）。我们选择的目标样本是为了最大限度地提高检测率，即附近狼疮恒星形成区域中几百万年历史的金牛座T型恒星。由于我们的目标很年轻，它们的亚恒星伴星也很年轻，因此由于仍在持续的收缩和吸积而自发光。我们使用 NACO 的立方体模式对接近 ESO-VLT 衍射极限且间距较大的物体进行成像。 2010 年 5 月，我们的所有 63 个目标均已在第 1 纪元被观测到，并且在 58 颗恒星周围发现了微弱的亚恒星候选伴星，预计间隔将降至 21 个天文单位。 NACO 计划于 2011 年 6 月进行第二次后续成像，以通过天体测量来测试所有检测到的候选者的陪伴情况。之后，所识别的共同移动伴星的亚恒星性质将通过后续光度测定和光谱学（2012）得到证实，这最终将使我们能够推导出这些物体的物理特性，如它们的有效温度、表面重力、半径和质量。然后，我们可以对间距在 10 到数十个天文单位之间的棕矮星沙漠的存在进行统计检验。然后，我们还将狼疮的结果与之前观察到的所有其他恒星形成区域和关联（如 TWA 或 Cha）的结果进行比较。