Multiwavelength observation of an active M-dwarf star EV Lac and its stellar flare accompanied by a delayed prominence eruption
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| Natura: | Preprint |
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2023
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| author | Inoue, Shun Enoto, Teruaki Namekata, Kosuke Notsu, Yuta Honda, Satoshi Maehara, Hiroyuki Zhang, Jiale Lu, Hong-Peng Uchida, Hiroyuki Tsuru, Takeshi Go Nogami, Daisaku Shibata, Kazunari |
| author_facet | Inoue, Shun Enoto, Teruaki Namekata, Kosuke Notsu, Yuta Honda, Satoshi Maehara, Hiroyuki Zhang, Jiale Lu, Hong-Peng Uchida, Hiroyuki Tsuru, Takeshi Go Nogami, Daisaku Shibata, Kazunari |
| contents | We conducted 4-night multiwavelength observations of an active M-dwarf star EV Lac on 2022 October 24$-$27 with simultaneous coverage of soft X-rays (NICER; 0.2$-$12 $\mathrm{keV}$, Swift XRT; 0.2$-$10 $\mathrm{keV}$), near-ultraviolet (Swift UVOT/UVW2; 1600$-$3500 Å), optical photometry (TESS; 6000$-$10000 Å), and optical spectroscopy (Nayuta/MALLS; 6350$-$6800 Å). During the campaign, we detected a flare starting at 12:28 UTC on October 25 with its white-light bolometric energy of $3.4 \times 10^{32}$ erg. At about 1 hour after this flare peak, our $\mathrm{Hα}$ spectrum showed a blue-shifted excess component at its corresponding velocity of $\sim 100 \: \mathrm{km \: s^{-1}}$. This may indicate that the prominence erupted with a 1-hour delay of the flare peak. Furthermore, the simultaneous 20-second cadence near-ultraviolet and white-light curves show gradual and rapid brightening behaviors during the rising phase at this flare. The ratio of flux in NUV to white light at the gradual brightening was $\sim 0.49$, which may suggest that the temperature of the blackbody is low ($< 9000 \: \mathrm{K}$) or the maximum energy flux of a nonthermal electron beam is less than $5\times10^{11} \: \mathrm{erg \: cm^{-2} \: s^{-1}}$. Our simultaneous observations of NUV and white-light flare raise the issue of a simple estimation of UV flux from optical continuum data by using a blackbody model. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2401_00399 |
| institution | arXiv |
| publishDate | 2023 |
| record_format | arxiv |
| spellingShingle | Multiwavelength observation of an active M-dwarf star EV Lac and its stellar flare accompanied by a delayed prominence eruption Inoue, Shun Enoto, Teruaki Namekata, Kosuke Notsu, Yuta Honda, Satoshi Maehara, Hiroyuki Zhang, Jiale Lu, Hong-Peng Uchida, Hiroyuki Tsuru, Takeshi Go Nogami, Daisaku Shibata, Kazunari Solar and Stellar Astrophysics High Energy Astrophysical Phenomena We conducted 4-night multiwavelength observations of an active M-dwarf star EV Lac on 2022 October 24$-$27 with simultaneous coverage of soft X-rays (NICER; 0.2$-$12 $\mathrm{keV}$, Swift XRT; 0.2$-$10 $\mathrm{keV}$), near-ultraviolet (Swift UVOT/UVW2; 1600$-$3500 Å), optical photometry (TESS; 6000$-$10000 Å), and optical spectroscopy (Nayuta/MALLS; 6350$-$6800 Å). During the campaign, we detected a flare starting at 12:28 UTC on October 25 with its white-light bolometric energy of $3.4 \times 10^{32}$ erg. At about 1 hour after this flare peak, our $\mathrm{Hα}$ spectrum showed a blue-shifted excess component at its corresponding velocity of $\sim 100 \: \mathrm{km \: s^{-1}}$. This may indicate that the prominence erupted with a 1-hour delay of the flare peak. Furthermore, the simultaneous 20-second cadence near-ultraviolet and white-light curves show gradual and rapid brightening behaviors during the rising phase at this flare. The ratio of flux in NUV to white light at the gradual brightening was $\sim 0.49$, which may suggest that the temperature of the blackbody is low ($< 9000 \: \mathrm{K}$) or the maximum energy flux of a nonthermal electron beam is less than $5\times10^{11} \: \mathrm{erg \: cm^{-2} \: s^{-1}}$. Our simultaneous observations of NUV and white-light flare raise the issue of a simple estimation of UV flux from optical continuum data by using a blackbody model. |
| title | Multiwavelength observation of an active M-dwarf star EV Lac and its stellar flare accompanied by a delayed prominence eruption |
| topic | Solar and Stellar Astrophysics High Energy Astrophysical Phenomena |
| url | https://arxiv.org/abs/2401.00399 |