APO3.5M Spectroscopic Monitoring Observations of a M-Dwarf

Home , Superflare

APO3.5m spectroscopic monitoring observations of a M-dwarf superflare star YZCMi with TESS and ARCSAT0.5m photometric and NICER soft X-ray observations Yuta Notsu1,2 (Yuta.Notsu＠colorado.edu), Adam Kowalski1,2, Hiroyuki Maehara3, Kosuke Namekata4, Suzanne Hawley5, James Davenport5, Teruaki Enoto4, Kenji Hamaguchi6, Satoshi Honda7, Shota Notsu8, Kai Ikuta4, Daisaku Nogami4, and Kazunari Shibata4

1 Univ. of Colorado Boulder (LASP), 2 National Solar Observatory, 3 NAOJ, 4 Kyoto Univ., 5 Univ. of Washington, 6NASA/GSFC, 7Univ. of Hyogo, 8Leiden Univ.

1.Introduction 4. Results - Observation on UT2019-Jan-26 sdss−g band (ARCSAT0.5m on UT2019−Jan−26) 1.05 APO observation time on UT2019−Jan−26 −0.2 TESS data target − comp Flare? One flare with continuum 1 hour 0 check − comp − 0.5 1 hour 1.04 YZCMi 0.2 4 enhancements. Very large flares 10-10 times more energetic 0.4 1.03 than the biggest solar flares (~1032erg). 0.6 - g-band: ~0.8mag Emissions 1.02 0.8 1 TESS: ~4% Relative magnitude during flares 1.01 1.2

Statistical studies of Kepler data Normalized PDCSAP FLUX -duration ~ 15-20min 1.4 1 (Maehara+12, Notsu+19) 1509.6 1509.7 1509.8 1509.9 1509.6 1509.7 1509.8 1509.9 Baricentric Julian Date [− 2457000.0] Baricentric Julian Date [− 2457000.0] - Flare energy and frequency Normalized Intensity depends on rotation period and age. No clear line wing - Even old Sun-like slowly-rotating stars shifts (or slight red can have superflares. cf. Press Release shifts ??) at AAS234 → Difference profile Other ◯ How superflare energy release and emission occur ? chromoshpheric lines Similar to solar flares ? (e.g., Hδ, Hγ, Ca K, Vida+19 Ca II 8542, He D3 ◯ Can coronal mass ejections 5876, Na D lines) (stellar CMEs) be detected ? also show similar - “Blue shifts” candidates caused by time evolutions. prominence eruptions (Vida+16&19, Moschou+19). - “Blue assymetries” caused by chromospheric dynamics (Honda+18). 5. Results - Observation on UT2019-Jan-27 1.5 APO observation time on UT2019−Jan−27 sdss−g band (ARCSAT0.5m on UT2019−Jan−27) sdss−u band (ARCSAT0.5m on UT2019−Jan−27) 1.02 (⇄ “Red asymetries” are 0.2 TESS data target − comp target − comp 1 hour 9−1 check − comp − 0.5 1 hour 3.2 check − comp − 0.4 usually observed Honda+18 14−1 1 hour 18−1 1.01 YZCMi 0.4 21−1 3.4 with solar flares.) 1 1 0.6 3.6 0.8 ◯ CME shocks cause 0.99 3.8 I (No. 1) + const − 0.5 1 Relative magnitude high-energy particles Relative magnitude 0.98 4 I(No. X) → Effects on (exo)planetary Normalized PDCSAP FLUX 1.2 4.2 0.97 atmosphere 1510.6 1510.7 1510.8 1510.9 1510.6 1510.7 1510.8 1510.9 1510.6 1510.7 1510.8 1510.9 0 (e.g., Segura+10, Airapetian+16, Yamashiki+19) Baricentric Julian Date [− 2457000.0] Baricentric Julian Date [− 2457000.0] Baricentric Julian Date [− 2457000.0]

6560 6564 6568 Wavelength [Å] A,B C NICER More detailed multi-wavelength observations are strongly needed !! Soft X-ray 2. Targets and Observations Apache Point Observatory (3.5m & 0.5m) Targets: YZCMi (M4.5V, V=11.2mag ) Single M-dwarf flare star (e.g., Kowalski+13)

A Observations: 2019UTJan-26, Jan 27, & Jan 28 B - Apache Point Observatory (APO) ARC 3.5m telescope high dispersion spectroscopy R=λ/Δλ~32500, λ : 3600-10000Å - APO ARCSAT 0.5m telescope multi-color photometry (u,g,r,i,V) C One flare without continuum enhancements. - TESS : single broad band high-precision TESS Only chromospheric and coronal emissions. photometry (6000-10000Å) (“Non-white light flare” like many solar flares ??) NICER Cycle1 Sector 7 (2019 Jan07 - Feb04) Hα: Slight blue shifts (especially decay phase). - NICER (Neutron Star Interior Composition Explorer) Other lines (e.g., Ca K, Ca II 8542, He D3 5876, soft X-ray spectroscopy (0.3-10keV) on ISS Na D lines) also show similar time evolutions.

3. Results - TESS light curve 6. Results - Observation on UT2019-Jan-28 7. Summary sdss−u band (ARCSAT0.5m on UT2019−Jan−28) 1.02 TESS data (ARCSAT0.5m on UT2019−Jan−28) 2.8 target − comp YZCMi check − comp − 0.6 Rotation Period : ~2.8day, 163 flare events Flare? 3 2019Jan10 Jan15 Jan20 Jan25 Jan30 3.2 From 3-night campaign observations of YZCMi, we 1.16 3.4 detected small flares with two different properties. YZCMi 3.6 1.14 Japan USA 1.01 3.8 (PI:Maehara) (PI:Notsu) - “Non-white-light” flares with chromospheric and 1.12 Nayuta2m(R=7500) ARC3.5m(R=32,500) 4 MITSUME0.5m(g,R,I) ARCSAT0.5m(ugriV) 4.2 Relative magnitude 1 hour coronal emissions (and possible slight blue shifts). 1.1 Kanata1.5m(R=400) NICER(X−ray) 1 hour 4.4

→Poster Normalized PDCSAP FLUX - Small “white-light” flares. 1.08 This study 4.6 by H. Maehara 1 1511.6 1511.7 1511.8 1511.9 1.06 1511.6 1511.7 1511.8 1511.9 Baricentric Julian Date [− 2457000.0] Baricentric Julian Date [− 2457000.0] 1.04 One flare with continuum [Ongoing discussions] 1.02 A,B 1 enhancements. Comparisons of line profiles with radiative Normalized PDCSAP FLUX 0.98 - u-band: ~0.7mag hydrodynamic simulation results 1495 1500 1505 1510 1515 TESS: ~0.05% (using RADYN code: e.g., Allred+06, Kowalski+17). Baricentric Julian Date [− 2457000.0] -duration ~ 10-15 min Jan25(0:00UT) Jan26 Jan27 Jan28 Jan29 1.12 YZCMi No clear line wing shifts [Next observational studies] 1.1 ARC3.5m(R=32,500) A - Observations of more flare stars ARCSAT0.5m(ugriV) (or slight red wing 1.08 NICER(X−ray) enhancements ??) → detecting larger flares with optical emissions. 1.06 1.04 Other chromoshpheric - Campaign observations in TESS Cycle 2 (and later) lines (e.g., Hδ, Hγ, Ca M-dwarf flare star EV Lac in 2019Sep. (Sector 16) 1.02 B 1 K, Ca II 8542, He D3

Normalized PDCSAP FLUX 5876, Na D lines) also - Proxima Centauri : TESS&NICER simultaneous 0.98 observations (just finished observations!!) 1509 1510 1511 1512 show similar time Baricentric Julian Date [− 2457000.0] evolutions.