Spectroscopy of nine eruptive young variables using TANSPEC

Ghosh, Arpan; Sharma, Saurabh; Ninan, Joe P.; Ojha, D. K.; Gour, Anubha S.; Pandey, Rakesh; Sinha, Tirthendu; Verma, Aayushi; Koshvendra, Singh,; Ghosh, S. K.; Kaur, Harjeet

doi:10.1007/s12036-023-09939-7

Cited by 1 publication

(1 citation statement)

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“…Spectroscopy is historically used to discriminate between types of bursts. Bona fide EX Lup-type outbursts show strong CO overtone emission, indicating a warm disk surface, along with strong Brγ emission produced by magnetospheric accretion (see, e.g., Lorenzetti et al 2012;Connelley & Reipurth 2018;Contreras Peña et al 2023;Ghosh et al 2023). Weaker accretion bursts should produce Brγ emission but are not expected to show CO emission; in stronger bursts the magnetospheric accretion paradigm may break down (e.g., Hartmann & Kenyon 1996).…”

Section: Spectroscopic Classification Of Bursts and Outburstsmentioning

confidence: 99%

The Accretion History of EX Lup: A Century of Bursts, Outbursts, and Quiescence

Wang 王,

Herczeg 沈,

Liu 刘

et al. 2023

ApJ

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EX Lup is the archetype for the class of young stars that undergoes repeated accretion outbursts of ∼5 mag at optical wavelengths that last for months. Despite extensive monitoring that dates back 130 yr, the accretion history of EX Lup remains mostly qualitative and has large uncertainties. We assess historical accretion rates of EX Lup by applying correlations between optical brightness and accretion, developed on multi-band magnitude photometry of the ∼2 mag optical burst in 2022. Two distinct classes of bursts occur: major outbursts (ΔV ∼ 5 mag) have year-long durations, are rare, reach accretion rates of M ̇ acc ∼ 10 − 7 M ⊙ yr−1 at peak, and have a total accreted mass of around 0.1 Earth mass. The characteristic bursts (ΔV ∼ 2 mag) have durations of ∼2–3 months, are more common, reach accretion rates of M ̇ acc ∼ 10 − 8 M ⊙ yr−1 at peak, and have a total accreted mass of around 10−3 Earth masses. The distribution of total accreted mass in the full set of bursts is poorly described by a power law, which suggests different driving causes behind the major outburst and characteristic bursts. The total mass accreted during two classes of bursts is around 2 times the masses accreted during quiescence. Our analysis of the light curves reveals a color-dependent time lag in the 2022 post-burst light curve, attributed to the presence of both hot and cool spots on the stellar surface.

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