标题： AF Lep b发现的意义：$β$小组中行星的质量-光度关系以及年轻伴星和自由漂浮行星的L-T过渡 显示英文标题

标题： Implications of the discovery of AF Lep b: The mass-luminosity relation for planets in the $β$ Pic Moving Group and the L-T transition for young companions and free-floating planets

摘要： 在10到200百万年之间的年轻行星的动态质量，在成像中被探测到，在塑造巨型行星形成模型方面起着至关重要的作用。 遗憾的是，只有少数这样的天体具有这些特征。 此外，年轻亚恒星伴星在近红外色-星等图中的演化模式可能与自由漂浮的天体不同，这可能是由于形成过程的不同。 最近在β Pic移动群（BPMG）中的AF Lep周围发现了一颗巨型行星，这鼓励我们重新审视这些问题。 我们考虑了BPMG中亚恒星天体的更新后的动态质量和亮度。 此外，我们将BPMG和其他年轻联合体中的亚恒星伴星和自由漂浮天体的特性进行了比较，并在色-星等图中重新绘制了这些天体的位置到尘埃温度平面上。 我们发现冷启动演化模型无法重现BPMG中亚恒星伴星的质量-亮度关系。 这与“热启动”情景的预测非常一致，并且与最近的行星形成模型一致。 我们发现在BPMG中，通过光度法和重新映射方法获得的质量与实际动态质量有相当好的一致性。 我们也发现了一个强烈的暗示，即年轻伴星的近红外色-星等图与属于相同年轻联合体的自由漂浮天体的图不同。 如果进一步的数据证实了这个最后的结果，那么这将意味着云沉降——可能导致L和T光谱类型之间的过渡——在年轻伴星中的有效温度低于自由漂浮的天体。 这可能暂时可以用不同的化学成分来解释。 显示英文摘要

摘要： Dynamical masses of young planets aged between 10 and 200 Myr detected in imaging play a crucial role in shaping models of giant planet formation. Regrettably, only a few such objects possess these characteristics. Furthermore, the evolutionary pattern of young sub-stellar companions in near-infrared colour-magnitude diagrams might diverge from free-floating objects, possibly due to differing formation processes. The recent identification of a giant planet around AF Lep, part of the beta Pic moving group (BPMG), encouraged us to re-examine these points. We considered updated dynamical masses and luminosities for the sub-stellar objects in the BPMG. In addition, we compared the properties of sub-stellar companions and free-floating objects in the BPMG and other young associations remapping the positions of the objects in the colour-magnitude diagram into a dustiness-temperature plane. We found that cold-start evolutionary models do not reproduce the mass-luminosity relation for sub-stellar companions in the BPMG. This aligns rather closely with predictions from 'hot start' scenarios and is consistent with recent planet formation models. We obtain rather good agreement with masses from photometry and the remapping approach compared to actual dynamical masses. We also found a strong suggestion that the near-infrared colour-magnitude diagram for young companions is different from that of free-floating objects belonging to the same young associations. If confirmed by further data, this last result would imply that cloud settling - which likely causes the transition between L and T spectral type - occurs at a lower effective temperature in young companions than in free-floating objects. This might tentatively be explained with a different chemical composition.