The Spectroscopic Variations of the FU Orionis Object V960 Mon

Takagi, Y.; Honda, Satoshi; Arai, Akira; Morihana, K.; Takahashi, Jun; Oasa, Yumiko; Itoh, Yoichi

doi:10.3847/1538-3881/aaa545

Cited by 10 publications

(12 citation statements)

References 28 publications

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“…The depth of Si II (6347.1 Å) showed a significant decrease in the spectrum between February 2015 and October 2015, while that of Fe II (5991.4 Å) decreased especially from 2017 January and 2018 January. The depth variation of Fe I, Ca I, and Fe II lines were comparable with the result of Takagi et al (2018). The wavelength shift was not detected in the absorption features listed in Table 2.…”

Section: Line Profiles Of Absorption Featuressupporting

confidence: 78%

“…The metal abundance was set to the solar value. Microturbulence was set to a value based on the empirical relations (Gray et al 2001;Takagi et al 2018).…”

Section: Line Profile Variationsmentioning

confidence: 99%

“…We conducted medium-resolution optical spectroscopic monitoring of V960 Mon to investigate the evolution of FUor outbursts (Takagi et al 2018). The Medium And Low-resolution Longslit Spectrograph (MALLS; Ozaki & Tokimasa 2005) equipped on the 2.0 m Nayuta Telescope at the Nishi-Harima Astronomical Observatory was used for the monitoring.…”

Section: Introductionmentioning

confidence: 99%

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Revealing the Spectroscopic Variations of FU Orionis Object V960 Mon with High-resolution Spectroscopy

Takagi

Honda

Arai

et al. 2020

ApJ

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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 highresolution spectroscopic observation of V960 Mon with the Subaru Telescope and the High Dispersion Spectrograph on 2018 January 8 and 2020 February 1. By comparing this spectrum with the archival data of the Keck Observatory and the High Resolution Echelle Spectrometer taken between 2014 and 2017, we found that the absorption profiles changed as V960 Mon faded. The line profile of absorption lines such as Fe I and Ca I can be explained by a sum of the spectra of the disk atmosphere and the central star. The model spectrum created to explain the variations of the line profiles suggests that the effective temperature of the central star is ∼5500 K, which is comparable to that of the pre-outburst phase with a distance of 1.6 kpc with Gaia. The spectrum also shows that the effective temperature of the disk atmosphere decreased as V960 Mon faded. The variations of the Hα and Ca II lines (8498.0 Å, 8542.1 Å) also show that the V960 Mon spectrum became central-star dominant.

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Section: Line Profiles Of Absorption Featuressupporting

confidence: 78%

“…The metal abundance was set to the solar value. Microturbulence was set to a value based on the empirical relations (Gray et al 2001;Takagi et al 2018).…”

Section: Line Profile Variationsmentioning

confidence: 99%

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Revealing the Spectroscopic Variations of FU Orionis Object V960 Mon with High-resolution Spectroscopy

Takagi

Honda

Arai

et al. 2020

ApJ

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“…We also detected several forbidden emission lines: (Magakian et al 2013;Takagi et al 2018;Kóspál et al 2020;Park et al 2020). In contrast, these lines are generally found in classical T Tauri stars as tracers of outflow or jets (Cabrit et al 1990;Hartmann 2009).…”

Section: Optical Spectroscopymentioning

confidence: 77%

A Study of the Photometric and Spectroscopic Variations of the Prototypical FU Orionis–type Star V1057 Cyg

Szabó

Kóspál

Ábrahám

et al. 2021

ApJ

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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 Telescope, Bohyunsan Optical Astronomy Observatory, Transiting Exoplanet Survey Satellite, and the Stratospheric Observatory for Infrared Astronomy. Our light curves show continuation of significant quasi-periodic variability in brightness over the past decade. Our spectroscopic observations show strong wind features, shell features, and forbidden emission lines. All of these spectral lines vary with time. We also report the first detection of [S II], [N II], and [O III] lines in the star.

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“…These outbursts have been explained by the onset of rapid mass accretion, rising from quiescent states of 10 −8 -10 −7 M yr −1 to as much as 10 −4 M yr −1 (Hartmann & Kenyon 1996). In their high states, FUors can also exhibit low-amplitude photometric/spectroscopic variability on ∼weekly timescales (Siwak et al 2018;Takagi et al 2018). Such high accretion rates, which can last for decades, may explain how stars accrete much of their mass, up to 10 −2 M for a single outburst (Hartmann & Kenyon 1996).…”

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confidence: 99%

A Study of Millimeter Variability in FUor Objects

Wendeborn

Espaillat

Macías

et al. 2020

ApJ

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FU Orionis objects (FUors) are rapidly-accreting, pre-main sequence objects that are known to exhibit large outbursts at optical and near-infrared wavelengths, with post-eruption, small-scale photometric variability superimposed on longer-term trends. In contrast, little is known about the variability of FUors at longer wavelengths. To explore this further, we observed six FUor objects using the NOrthern Extended Millimeter Array (NOEMA) and for a subset of three objects we obtained coordinated observations with NOEMA and the Lowell Discovery Telescope (LDT). In combination with previously published NOEMA observations from 2014, our 2017 observations of V1735 Cyg provide the first detection of variability in an FUor object at 2.7 mm. In the absence of significant optical variability, we discount the possibility that the mm flux density changed as a result of irradiation from the central disk. In addition, a change in the dust mass due to infall is highly unlikely. A plausible explanation for the change in 2.7 mm flux density is variability in free-free emission due to changes in the object's jet/wind. Thus, it may be that free-free emission in some FUor objects is significant at ∼3 mm and must be considered when deriving disk masses in order to help constrain the mechanism responsible for triggering FUor outbursts.

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The Spectroscopic Variations of the FU Orionis Object V960 Mon

Cited by 10 publications

References 28 publications

Revealing the Spectroscopic Variations of FU Orionis Object V960 Mon with High-resolution Spectroscopy

Revealing the Spectroscopic Variations of FU Orionis Object V960 Mon with High-resolution Spectroscopy

A Study of the Photometric and Spectroscopic Variations of the Prototypical FU Orionis–type Star V1057 Cyg

A Study of Millimeter Variability in FUor Objects

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