Quest for the Donor Star in the Magnetic Precataclysmic Variable V1082 Sgr

K2 study of the Magnetic Precataclysmic Variable V1082 Sagittarius

We present a long-term light curve of the precataclysmic variable (CV) V1082 Sgr obtained by the K2-mission over the course of 81 days. We analyze the entire complex light curve as well as explore several sections in detail with a sliding periodogram. The long dataset allows the first detection of the orbital period in the light curve, as well as the confirmation of cyclical variability on a longer timescale of about a month. A portion of the light curve in deep minimum reveals a clean, near-sinusoidal variability attributed to the rotation of the spotted surface of the donor star. We model th…

X3: a high-mass Young Stellar Object close to the supermassive black hole Sgr~A*

To date, the proposed observation of Young Stellar Objects (YSOs) in the Galactic center (GC) still raises the question where and how these objects could have formed due to the violent vicinity of Sgr~A*. Here, we report the multi-wavelength detection of a highly dynamic YSO close to Sgr~A* that might be a member of the IRS13 cluster. We observe the beforehand known coreless bow-shock source X3 in the near- and mid-infrared (NIR/MIR) with SINFONI (VLT), NACO (VLT), ISAAC (VLT), VISIR (VLT), SHARP (NTT), and NIRCAM2 (KECK). In the radio domain, we use CO continuum and H30$α$ ALMA observations t…

SGR 1935+2154的宁静局部环境：其前身的线索

SGR 1935+2154's Quiet Local Environment: Clues for Its Progenitor

通过研究SGR 1935+2154的局部星系环境，发现其周围恒星密度较低，暗示其可能由非超大质量恒星坍缩或双星合并形成，而非超大质量恒星坍缩。

2D kinematics of massive stars near the Galactic Center

The presence of massive stars (MSs) in the region close to the Galactic Center (GC) poses several questions about their origin. The harsh environment of the GC favors specific formation scenarios, each of which should imprint characteristic kinematic features on the MSs. We present a 2D kinematic analysis of MSs in a GC region surrounding Sgr A* based on high-precision proper motions obtained with the Hubble Space Telescope. Thanks to a careful data reduction, well-measured bright stars in our proper-motion catalogs have errors better than 0.5 mas yr$^{-1}$. We discuss the absolute motion of t…

S 星团中的候选年轻恒星体：对靠近 Sgr A* 的低质量 G 型天体子种群的运动学分析

Candidate Young Stellar Objects in the S-cluster: The Kinematic Analysis of a Sub-population of the Low-mass G-objects close to Sgr A*

本文结合测光、HYPERION 辐射转移建模与开普勒轨道拟合，分析 S 星团近 Sgr A* 尘埃源，支持其为嵌埋于尘埃包层中的 I 类年轻恒星体。

长寿命双星中子星合并残留物的电磁辐射I：问题的表述

Electromagnetic emission from long-lived binary neutron star merger remnants I: formulation of the problem

双中子星（BNS）合并是解释短伽马射线暴（SGRB）现象的主要模型，SGRB是宇宙中最明亮的爆炸之一。最近对SGRB的持久X射线余辉的观测挑战了标准范式，并表明在很大一部分事件中，可能形成长寿的中子星（NS），而不是黑洞。了解这些余辉背后的机制是必要的，以解决有关SGRB中央引擎的性质公开的问题。然而，最近的理论进展一直受到阻碍的事实，即余辉发射的时间尺度的利益是无法访问的数值相对论模拟。在这里，我们提出了一个详细的模型来弥合合并过程的数值模拟和余辉的相关时间尺度之间的差距，假设合并的结果在一个长寿命的NS。该模型是制定在一组耦合的微分方程，遵循合并后的系统的演变，并预测其电磁（EM）发射在一个自洽的方式，从初始数据，可以从BNS合并模拟提取，并考虑到最相关的辐射过程。此外，该模式可以容纳在任何时间的演变过程中，以及不同的情况下，即时SGRB排放的残余NS崩溃。对BNS合并感兴趣的第二个主要原因是，它们被认为是最有希望的引力波（GW）源，可用于今年上线的先进地面探测器网络LIGO/Virgo的探测。在合并和合并后阶段进行EM和GW联合观测的多信使天文学可以大大提高这两种观测的科学产出。但是，实际收益取决于...