High-resolution spectroscopic monitoring observations of FU Orionis-type object, V960 Mon
Sunkyung Park, Jeong-Eun Lee, Tae-Soo Pyo, Daniel T. Jaffe, Gregory N. Mace, Hyun-Il Sung, Sang-Gak Lee, Wonseok Kang, Hyung-Il Oh, Tae Seog Yoon, Sung-Yong Yoon, Joel D. Green
We present the results of high-resolution (R $\ge$ 30,000) optical and near-infrared spectroscopic monitoring observations of a FU Orionis-type object, V960 Mon, which underwent an outburst in 2014 November. We have monitored this object with the Bohyunsan Optical Echelle Spectrograph (BOES) and the Immersion GRating INfrared Spectrograph (IGRINS) since 2014 December. Various features produced by a wind, disk, and outflow/jet were detected. The wind features varied over time and continually weakened after the outburst. We detected double-peaked line profiles in the optical and near-infrared, and the line widths tend to decrease with increasing wavelength, indicative of Keplerian disk rotation. The disk features in the optical and near-infrared spectra fit well with G-type and K-type stellar spectra convolved with a kernel to account for the maximum projected disk rotation velocity of about 40.3$\pm$3.8 km s$^{-1}$ and 36.3$\pm$3.9 km s$^{-1}$, respectively. We also report the detection of [S II] and H$_{2}$ emission lines, which are jet/outflow tracers and rarely found in FUors.
We present the results of the spectroscopic monitoring of the FU Orionis type star V960 Mon. Spectroscopic variations of a FU Orionis type star will provide valuable information of its physical nature and the mechanism of the outburst. We conducted medium-resolution (R~10000) spectroscopic observations of V960 Mon with 2m Nayuta telescope at the Nishi-Harima Astronomical Observatory, from 2015 January to 2017 January for 53 nights in total. We focused on H alpha line and nearby atomic lines, and detected the strength variations in both absorption and emission lines. The observed variation in t…
Among the low-mass pre-main sequence stars, a small group called FU Orionis-type objects (FUors) are notable for undergoing powerful accretion outbursts. V1057 Cyg, a classical example of an FUor, went into outburst around 1969-1970, after which it faded rapidly, making it the fastest fading FUor known. Around 1995, a more rapid increase in fading occurred. Since that time, strong photometric modulations have been present. We present nearly 10 years of source monitoring at Piszkéstető Observatory, complemented with optical/near-infrared photometry and spectroscopy from the Nordic Optical Teles…
We present the results of the high-resolution spectroscopy of the FU Orionis-type star V960 Mon. The brightness of V960 Mon decreased continuously after the outburst was detected in 2014 November. During this dimming event, we have carried out medium-resolution spectroscopic monitoring observations and found that the equivalent width of the absorption features showed variations. To further investigate the spectroscopic variations, we conducted a high-resolution spectroscopic observation of V960 Mon with the Subaru Telescope and the High Dispersion Spectrograph on 2018 January 8 and 2020 Februa…
We have obtained low-resolution optical (0.7-0.98 micron) and near-infrared (1.11-1.34 micron and 0.8-2.5 micron) spectra of twelve isolated planetary-mass candidates (J = 18.2-19.9 mag) of the 3-Myr sigma Orionis star cluster with a view to determining the spectroscopic properties of very young, substellar dwarfs and assembling a complete cluster mass function. We have classified our targets by visual comparison with high- and low-gravity standards and by measuring newly defined spectroscopic indices. We derived L0-L4.5 and M9-L2.5 using high- and low-gravity standards, respectively. Our targ…
We have conducted a homogenous near-IR spectroscopic survey of 33 objects with varying degrees of similarity to FU~Orionis. Common spectroscopic features that are characteristic of the three classical FUors FU Ori, V1057 Cyg, and V1515 Cyg are: strong CO absorption, weak metal absorption, strong water bands, low gravity, strong blue shifted He I absorption, and few (if any) emission lines. Based on these criteria, we classify the 33 objects as either bona fide FUors (eruption observed), FUor-like objects (eruption not observed), or peculiar objects with some FUor-like characteristics, and pres…
Context. Only a few open clusters are as important for the study of stellar and substellar objects, and their formation and evolution, as the young sigma Orionis cluster. However, a complete spectroscopic characterisation of its whole stellar population is still missing. Aims. We filled most of that gap with a large spectroscopic and astrometric survey of targets towards sigma Orionis. Eventually, it will be one of the open clusters with the lowest proportion of interlopers and the largest proportion of confirmed cluster members with known uncontrovertible youth features. Methods. We acquired …
During their formation phase stars gain most of their mass in violent episodic accretion events, such as observed in FU Orionis (FUor) and EXor stars. V346 Normae is a well-studied FUor that underwent a strong outburst beginning in $\sim1980$. Here, we report photometric and spectroscopic observations which show that the visual/near-infrared brightness has decreased dramatically between the 1990s and 2010 ($ΔR\approx10.9^{\rm m}$, $ΔJ\approx7.8^{\rm m}$, $ΔK\approx5.8^{\rm m}$). The spectral properties of this fading event cannot be explained with variable extinction alone, but indicate a drop…
A coordinated X-ray and Optical Campaign of the Nearest Massive Eclipsing Binary, $δ$ Orionis Aa: IV. A multiwavelength, non-LTE spectroscopic analysis
We present new SOFIA-FORCAST observations obtained in Feburary 2016 of the archetypal outbursting low mass young stellar object FU Orionis, and compare the continuum, solid state, and gas properties with mid-IR data obtained at the same wavelengths in 2004 with Spitzer-IRS. In this study, we conduct the first mid-IR spectroscopic comparison of an FUor over a long time period. Over a 12 year period, UBVR monitoring indicates that FU Orionis has continued its steady decrease in overall brightness by ~ 14%. We find that this decrease in luminosity occurs only at wavelengths < 20 microns. In parti…
New results from long-term optical photometric observations of the pre-main sequence star GM Cep from UX Orionis type are reported. During ongoing photometric monitoring of the GM Cep four deep minimums in brightness are observed. The collected multicolour photometric data shows the typical of UXor variables colour reversal during the minimums in brightness. Recent $BVRI$ photometric observations of GM Cep have been collected from November 2014 to October 2020.
Massive stars play a significant role in the chemical and dynamical evolution of galaxies. However, much of their variability, particularly during their evolved supergiant stage, is poorly understood. To understand the variability of evolved massive stars in more detail, we present a study of the O9.2Ib supergiant $ζ$ Ori Aa, the only currently confirmed supergiant to host a magnetic field. We have obtained two-color space-based BRIght Target Explorer photometry (BRITE) for $ζ$ Ori Aa during two observing campaigns, as well as simultaneous ground-based, high-resolution optical CHIRON spectrosc…
A Coordinated X-ray and Optical Campaign of the Nearest Massive Eclipsing Binary, delta Orionis Aa: III. Analysis of Optical Photometric MOST and Spectroscopic (Ground Based) Variations
我们报告了来自MOST空间望远镜的高精度测光和三重系统delta Ori A的地基光谱学，该系统由P = 5.7d的二进制O9.5II+早期B（Aa1和Aa2）和更遥远的第三（O9 IV P > 400 yrs）组成。这些数据是与钱德拉X射线天文台的X射线光谱学一起收集的。由于连续3周的覆盖，MOST光变曲线首次在非相位数据中揭示了Aa1和Aa2之间的清晰日食。根据光谱，我们有一个很好的约束径向速度曲线Aa1。虽然我们无法恢复径向速度的变化的二级恒星，我们能够约束这个系统的几个基本参数，并确定一个近似的质量使用拱点运动的主要。我们还检测到二阶调制在12个独立的频率与间距潮汐影响的振荡指示。这些间距从未在大质量双星中看到过，使该系统成为少数几个显示潮汐诱导脉动证据的双星之一。
Multi-color characterization of optically invisible FU Orionis-type outbursts: Demonstration and prospects for the WINTER survey
Harvard & Smithsonian（哈佛-史密森天体物理中心）；Columbia University（哥伦比亚大学）；Flatiron Institute（平顿研究所）；California Institute of Technology（加州理工学院）；Massachusetts Institute of Technology（麻省理工学院）
We perform 3D hydrodynamics simulations of disc-disc stellar flybys with on-the-fly Monte Carlo radiative transfer. We show that pre-existing circumstellar discs around both stars result in fast rising ($\sim$yrs) outbursts lasting 2-5 times longer than for a star-disc flyby. The perturber always goes into outburst ($\dot{M}>10^{-5}~{\rm M_{\odot}~ yr^{-1}}$). Whereas we find that the primary goes into a decades long outburst only when the flyby is retrograde to the circumprimary disc rotation. High accretion rates during the outburst are triggered by angular momentum cancellation in misaligne…
Constraining mass ratio and extinction in the FU Orionis binary system with infrared integral field spectroscopy
我们报告低分辨率近红外光谱观测的爆发星FU猎户座使用积分场摄谱仪项目1640安装在Palomar黑尔望远镜。这项工作的重点是阐明位于FU Ori以南0.5”的微弱源的性质，并于2003年被确定为FU Ori S。我们首先使用我们的观察与已公布的数据相结合，以证明这两颗恒星确实是物理相关的，并形成一个真正的双星对。然后，我们继续使用阻尼LOCI算法提取J和H波段分光光度法，这是一种为IFS的高对比度科学量身定制的还原方法。这是第一次报告这种技术的高精度的通信，由项目1640团队开创，在一个微弱的天文来源。我们使用我们的低分辨率近红外光谱结合10.2微米干涉数据来限制FU Ori S的红外过量。然后，我们专注于估计FU Ori S的体物理性质。我们的模型导致严重红化的对象的估计，A_V =8-12，有效温度为~ 4000-6500 K。最后，我们把这些结果放在FU Ori N-S系统的背景下，认为我们的分析提供了证据，FU Ori S可能是这个双星系统中更大的组成部分
Understanding how bodies interact with each other and with disk material holds the key to understanding the architecture of stellar systems and of planetary systems. While the interactions between point sources can be described by simple gravity, interactions with disk material require further knowledge about the gas viscosity and dust microphysics that needs to be included when simulating disk-body interactions. Pre-main-sequence multiple systems provide us with a unique laboratory to calibrate fundamental parameters such as the viscosity and to test theories of hydrodynamic processes that mi…
The surroundings of massive protostars constitute an accretion disc which has numerically been shown to be subject to fragmentation and responsible for luminous accretion-driven outbursts. Moreover, it is suspected to produce close binary companions which will later strongly influence the star's future evolution in the Hertzsprung-Russel diagram. We present three-dimensional gravitation-radiation-hydrodynamic numerical simulations of 100 Mo pre-stellar cores. We find that accretion discs of young massive stars violently fragment without preventing the (highly variable) accretion of gaseous clu…
V7995 Sgr: A New FU Orionis Accretion Outburst Near NGC 6589/6590
California Institute of Technology（加州理工学院）；Columbia University（哥伦比亚大学）；Center for Computational Astrophysics, Flatiron Institute（平顿研究所计算天体物理中心）；Harvard University（哈佛大学）；Jet Propulsion Laboratory, California Institute of Technology（加州理工学院喷气推进实验室）
本文报告了 V7995 Sgr 在 2024 年底达到峰值亮度的一次 FU Orionis 型爆发，基于多波段光变曲线和光谱观测，确认其由吸积盘驱动并伴有强风。
Gaia19fct is one of the Gaia-alerted eruptive young stars that has undergone several brightening events. We conducted monitoring observations using multi-filter optical and near-infrared photometry, as well as near-infrared spectroscopy, to understand the physical properties of Gaia19fct and investigate whether it fits into the historically defined two classes. We present the analyses of light curves, color variations, spectral lines, and CO modeling. The light curves show at least five brightening events since 2015, and the multi-filter color evolutions are mostly gray. The gray evolution ind…
A Study of Mid-Infrared Sources that Dramatically Brightened
我们目前的近红外光度和光谱观测中红外（MIR）源显着增亮的结果。利用IRAS、AKARI和WISE点源星表，我们发现4个源（IRAS 19574+491、V2494 Cyg、IRAS 22343+7501和V583 Cas）在MIR波长上在观测时间上的20-30年差异上显著增亮。除了天鹅座V2494被认为是猎户座FU星之外，对这些来源的了解很少。我们的观测清楚地将IRAS 22343+7501分解为4颗恒星（2 MASS J22352345+7517076，2 MASS J22352442+7517037，[RD 95] C和2 MASS J22352497+7517113），并获得了所有4个源的第一个JHK光度数据。其中两颗恒星（2 MASS J22352442+7517037和2 MASS J22352497+7517113）被称为T Tau星。光谱观测表明IRAS 19574+9441是一颗M型演化星，V583 Cas是一颗碳星。2 MASS J22352345+7517076可能是一颗YSO，从我们的观测判断，它具有无特征的近红外（NIR）光谱，并且在NIR中也显示出显着的增亮（在KS波段约4个星等）。本文讨论了中红外光谱中出现剧烈增亮的可能原因。
By analyzing photometric and spectroscopic time series in this paper, we show that the pulsator V764 Mon, assumed to be the brightest RR Lyrae star in the sky, is in fact a rapidly rotating delta Scuti star with an unusually long dominant period (P1=0.29 d). Our spectroscopy confirmed the discovery of the Gaia satellite about the binarity of V764 Mon. In the case of HY Com, a `bona fide' RRc star, we present its first complete radial velocity curve. Additionally, we found that the star continues its strong phase variation reported before.
