发表机构
Universidade Federal de Sergipe; Observatório Nacional; Laboratório Nacional de Astrofísica; NASA/GSFC; University of Maryland, Baltimore County; Instituto Nacional de Pesquisas Espaciais（塞尔希培联邦大学; 国家天文台; 国家天体物理实验室; 美国宇航局戈达德太空飞行中心; 马里兰大学巴尔的摩县分校; 国家空间研究所）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本文通过多波段观测表征了IPHAS J190812.63+045728.1，发现其为轨道周期5.073小时的掩食激变变星，具有深掩食、频繁爆发及中间极与矮新星之间的模糊特征，为吸积盘不稳定性模型提供基准。
AI 中文摘要
我们对IPHAS J190812.63+045728.1进行了多波段表征。该系统最初由XMM-Newton偶然观测到后被我们独立发现，随后利用SPARC4/OPD进行光学测光、利用GMOS/Gemini South进行光谱观测，并探索了存档的TESS和ZTF观测数据，我们揭示该系统是一个轨道周期为5.073小时的掩食吸积白矮星（WD）系统。深光学掩食和平底X射线掩食完全遮蔽了白矮星和吸积盘，提供了对伴星的模型无关、无污染视角，我们将其分类为M2.3矮星，质量约为0.50个太阳质量。该系统是一个中等光度（0.3-10 keV波段的X射线光度约为1.7×10^32 erg s^-1）的硬热X射线源（与从约26 keV的k T冷却下来的激波加热等离子体一致）。虽然这些X射线性质是低光度中间极（IPs）的典型特征，但长期存档测光揭示了频繁的大振幅爆发（ZTF zr波段约2星等），这是矮新星的典型特征，而对IPs来说则不寻常。HeII λ4686发射线的微弱强度使我们无法在IP和矮新星情景之间做出决定。另一方面，光学和X射线光变曲线没有表现出由白矮星自转引起的周期性变化。如果该系统确实是IP，其吸积几何可能不寻常，而类似矮新星的爆发表明盘不稳定性，这将使IPHAS J190812.63+045728.1成为在存在磁截断吸积盘情况下测试盘不稳定性模型的基准。否则，该系统是一颗矮新星，其X射线性质处于其类别的极端端。
英文摘要
We present a multi-wavelength characterization of IPHAS J190812.63+045728.1. Independently discovered by us after being serendipitously observed by XMM-Newton, followed up with optical photometry with SPARC4/OPD and spectroscopy with GMOS/Gemini South, and exploring archival TESS and ZTF observations, we reveal the system to be an eclipsing accreting white dwarf (WD) system with an orbital period of 5.073 h. The deep optical and flat-bottomed X-ray eclipses completely occult the WD and the accretion disk, providing a model-independent, uncontaminated view of the donor star which we classify as an M2.3 dwarf with a mass of $\sim 0.50\,M_\odot$. The system is a modestly luminous (L$_{x;0.3-10 keV} \sim$ 1.7 $\times$ 10$^{32}$ erg s$^{-1}$) hard thermal (consistent with a shock-heated plasma cooling down from $k$T $\sim$ 26 keV) X-ray source. While these X-ray properties are typical of low luminosity intermediate polars (IPs), long-term archival photometry reveals frequent, large-amplitude outbursts ($Δm \sim 2$ mag in the ZTF $zr$ band) that are the typical characteristics of dwarf novae, and would be unusual for IPs. The weakness of the HeII $λ$4686 emission line does not allow us to decide between the IP and the dwarf nova scenarios. On the other hand, the optical and X-ray light curves do not exhibit periodic variations caused by the WD rotation. If the system is indeed an IP, the accretion geometry is likely unusual while the dwarf nova-like outbursts indicating disk instabilities would make IPHAS J190812.63+045728.1 a benchmark for testing disk instability models in the presence of magnetically truncated accretion disks. Otherwise, the system is a dwarf nova with X-ray properties at the extreme end of its class.
CommentsAccepted by ApJ
