Decoding the X-ray flare from MAXI J0709-159 using optical spectroscopy and multi-epoch photometry
Suman Bhattacharyya, Blesson Mathew, Savithri H Ezhikode, S Muneer, Selvakumar G, Maheswer G, R. Arun, Hema Anilkumar, Gourav Banerjee, Pramod Kumar S, Sreeja S… 展开作者
Suman Bhattacharyya, Blesson Mathew, Savithri H Ezhikode, S Muneer, Selvakumar G, Maheswer G, R. Arun, Hema Anilkumar, Gourav Banerjee, Pramod Kumar S, Sreeja S Kartha, KT Paul, C. Velu
备注：
9 pages, 5 figures, 1 table, accepted for publication in ApJL
We present a follow-up study on the recent detection of two X-ray flaring events by MAXI/GSC observations in soft and hard X-rays from MAXI J0709-159 in the direction of HD 54786 (LY CMa), on 2022 January 25. The X-ray luminosity during the flare was around 10^(37) erg/s (MAXI), which got reduced to 10^(32) erg/s (NuSTAR) after the flare. We took low-resolution spectra of HD 54786 from HCT and VBT facilities in India, on 2022 February 1 and 2. In addition to H-alpha emission, we found emission lines of He I in the optical spectrum of this star. By comparing our spectrum of the object with those from literature we found that He I lines show variability. Using photometric study we estimate that the star is having effective temperature of 20000 K. Although HD 54786 is reported as a supergiant in previous studies, our analysis favours it to be evolving off the main sequence in the Color-Magnitude Diagram. We could not detect any infrared excess, ruling out the possibility of IR emission from a dusty circumstellar disc. Our present study suggests that HD 54786 is a Be/X-ray binary system with a compact object companion, possibly a neutron star.
In this study, we present the unpublished flare data collected from 222 flares detected in the B band observations of five stars and the results derived by statistical analysis and modeling of these data. Six basic properties have been found with a statistical analysis method applied to all models and analyses for the flares detected in the B band observation of UV Ceti type stars. We have also compared the U and B bands with the analysis results. This comparison allowed us to evaluate the methods used in the analyses. The analyses provided the following results. (1) The flares were separated …
On the basis of the 30-year ago ground-based photometry and the recent Kepler space experiment there have been considered frequencies of occurrence and energetics of the solar-type stellar flares. It was concluded that frequencies of occurrence of such flares are proportional to sizes of stellar surfaces, and estimates of maximum flare radiation from the results of the ground-based photometry and space observations practically coincide.
We report on K2 Campaign 8 measurements of a huge white light flare on the L1 dwarf SDSSp J005406.55-003101.8 (EPIC 220186653). The source is a typical L1 dwarf at a distance of $\sim50$ pc, probably an old hydrogen-burning star rather than a young brown dwarf. In the long (30-minute) cadence photometry, the flare peak is 21 times the flux of the stellar photosphere in the broad optical Kepler filter, which we estimate corresponds to $ΔV \approx -7.1$. The total equivalent duration of the flare is 15.4 hr. We estimate the total bolometric energy of the flare was $4 \times 10^{33}$ erg, more po…
We present a homogeneous survey of line and continuum emission from near-ultraviolet (NUV) to optical wavelengths during twenty M dwarf flares with simultaneous, high cadence photometry and spectra. These data were obtained to study the white-light continuum components at bluer and redder wavelengths than the Balmer jump. Our goals were to break the degeneracy between emission mechanisms that have been fit to broadband colors of flares and to provide constraints for radiative-hydrodynamic (RHD) flare models that seek to reproduce the white-light flare emission. The main results from the contin…
In this paper, we present the results from spectroscopic and photometric observations of the M-type flare star YZ CMi in the framework of the Optical and Infrared Synergetic Telescopes for Education and Research (OISTER) collaborations during the Transiting Exoplanet Survey Satellite (TESS) observation period. We detected 145 white-light flares from the TESS light curve and 4 H$α$ flares from the OISTER observations performed between 2019-01-16 and 2019-01-18. Among them, 3 H$α$ flares were associated with white-light flares. However, one of them did not show clear brightening in continuum; du…
We present sub-second, continuous-coverage photometry of three flares on the dM3.5e star, EQ Peg A, using custom continuum filters with WHT/ULTRACAM. These data provide a new view of flare continuum emission, with each flare exhibiting a very distinct light curve morphology. The spectral shape of flare emission for the two large-amplitude flares is compared with synthetic ULTRACAM measurements taken from the spectra during the large 'megaflare' event on a similar type flare star. The white light shape during the impulsive phase of the EQ Peg flares is consistent with the range of colors derive…
High-Time-Cadence Spectroscopy and Photometry of Stellar Flares on M-dwarf YZ Canis Minoris with Seimei Telescope and TESS. II. Statistical Properties of Blue/Red Asymmetries in the H$α$ Line
Doppler imaging combined with high-cadence photometry. I. Revisiting the surface of a pre-main-sequence flare star
Kyoto University（京都大学）；Ankara University（安卡拉大学）；Max-Planck-Institut für Sonnensystemforschung（马克斯·普朗克太阳系研究所）；Hitotsubashi University（一桥大学）；The Hakubi Center for Advanced Research, Kyoto University（京都大学哈库比高级研究中心）；NASA Goddard Space Flight Center（美国国家航空航天局戈达德太空飞行中心）；The Catholic University of America（美利坚天主教大学）；National Astronomical Observatory of Japan（日本国立天文台）；Nishi-Harima Astronomical Observatory, University of Hyogo（兵库县立西播磨天文台）
We present the results of a campaign to monitor active M dwarfs using infrared spectroscopy, supplemented with optical photometry and spectroscopy. We detected 16 flares during nearly 50 hours of observations on EV Lac, AD Leo, YZ CMi, and VB8. The three most energetic flares also showed infrared emission, including the first reported detections of Pβ, Pγ, He I 10830Åand Brγduring an M dwarf flare. The strongest flare (Δu = 4.02 on EV Lac) showed emission from Hγ, Hδ, He I 4471Å, and Ca II K in the UV/blue and Pβ, Pγ, Pδ, Brγ, and He I 10830Åin the infrared. The weaker flares (Δu = 1.68 on EV …
23 giant flares from 13 active stars (eight RS CVn systems, one Algol system, three dMe stars and one YSO) were detected during the first two years of our all-sky X-ray monitoring with the gas propotional counters (GSC) of the Monitor of All-sky X-ray Image (MAXI). The observed parameters of all of these MAXI/GSC flares are found to be at the upper ends for stellar flares with the luminosity of 10^(31-34) ergs s-1 in the 2-20 keV band, the emission measure of 10^(54-57) cm-3, the e-folding time of 1 hour to 1.5 days, and the total radiative energy released during the flare of 10^(34-39) ergs. …
Getman et al. (2021) reports the discovery, energetics, frequencies, and effects on environs of $>1000$ X-ray super-flares with X-ray energies $E_X \sim 10^{34}-10^{38}$~erg from pre-main sequence (PMS) stars identified in the $Chandra$ MYStIX and SFiNCs surveys. Here we perform detailed plasma evolution modeling of $55$ bright MYStIX/SFiNCs super-flares from these events. They constitute a large sample of the most powerful stellar flares analyzed in a uniform fashion. They are compared with published X-ray super-flares from young stars in the Orion Nebula Cluster, older active stars, and the …
In this study, a new method is presented to classify flares derived from the photoelectric photometry of UV Ceti type stars. This method is based on statistical analyses using an independent samples t-test. The data used in analyses were obtained from four flare stars observed between 2004 and 2007. The total number of flares obtained in the observations of AD Leo, EV Lac, EQ Peg, and V1054 Oph is 321 in the standard Johnson U band. As a result flares can be separated into two types, slow and fast, depending on the ratio of flare decay time to flare rise time. The ratio is below 3.5 for all sl…
We present a study of flare rates, rotation periods, and spectroscopic activity indicators of 125 single stars within 15 parsecs and with masses between 0.1$-$0.3 $M_\odot$ observed during the first year of the TESS mission, with the goal of elucidating the relationship between these various magnetically connected phenomena. We gathered multi-epoch high resolution spectra of each target and we measured equivalent widths of the activity indicators Helium I D$_3$, $Hα$, and the Calcium infrared triplet line at 8542.09 angstroms. We present 18 new rotation periods from MEarth photometry and 19 ne…
Solar flare activity is characterised by different classification systems, both in optical and X-ray ranges. The most generally accepted classifications of solar flares describe important parameters of flares such as the maximum of brightness of the flare in the in optical range - $H_α$ flare class (change from F to B), area of the flare in $H_α$ (change from S for areas less than 2 square degrees to 4 for areas more than 24.7 square degrees) and the maximum amplitude of the soft X-ray (SXR-flux) in the band 0.1 -- 0.8 nm ($F_{0.1-0.8}^{max}$) -- X-ray flares of classes from C to X. A new clas…
High-Time-Cadence Spectroscopy and Photometry of Stellar Flares on M-dwarf YZ Canis Minoris with Seimei Telescope and TESS. I. Discovery of Rapid and Short-Duration Prominence Eruptions
Eclipsing Stellar Flare on the Demon Star Algol Binary System Observed during the MAXI-NICER Follow-up Campaign in 2018
Kyoto University（京都大学）；Chiba University（千叶大学）；RIKEN Center for Advanced Photonics (RAP)（理化学研究所先进光子学中心）；University of Colorado Boulder（科罗拉多大学博尔德分校）；National Solar Observatory（国家太阳观测台）；NASA’s Goddard Space Flight Center（美国宇航局戈达德太空飞行中心）
The study is devoted to search for flare stars among confirmed members of Galactic open clusters using high-cadence photometry from {\it TESS} mission. We analyzed 957 high-cadence light curves of members from 136 open clusters. As a result, 56 flare stars were found, among them 8 hot B-A type objects. Of all flares, 63\% were detected in a sample of cool stars ($T_{\rm eff}<5000$~K), and 29\% -- in stars of spectral type G, while 23\% in K-type stars and approximately 34\% of all detected flares are in M-type stars. Using the FLATW'RM (FLAre deTection With Ransac Method) flare finding algorit…
We present a statistical analysis of properties of Soft X-Ray (SXR) emission, plasma temperature (T), and emission measure (EM), derived from GOES observations of flares in 2002-2017. The temperature and emission measures are obtained using the TEBBS algorithm (Ryan et al. 2012), which delivers reliable results together with uncertainties even for weak B-class flare events. More than 96% of flares demonstrate a sequential appearance of T, SXR, and EM maxima, in agreement with the expected behavior of the chromospheric evaporation process. The relative number of such flares increases with incre…
We present our new photometry of DV Psc obtained in 2010 and 2011, and new spectroscopic observation on Feb. 14, 2012. During our observations, three flare-like events might be detected firstly in one period on DV Psc. The flare rate of DV Psc is about 0.017 flares per hour. Using Wilson-Devinney program, we derived the preliminary starspot parameters. Moreover, the magnetic cycle is 9.26(+/-0.78) year analyzed by variabilities of Max.I - Max.II.
Using data obtained during the RATS-Kepler project we identified one short duration flare in a 1 hour sequence of ground based photometry of the dwarf star KIC 5474065. Observations made using GTC show it is a star with a M4 V spectral type. Kepler observations made using 1 min sampling show that KIC 5474065 exhibits large amplitude (deltaF/F>0.4) optical flares which have a duration as short as 10 mins. We compare the energy distribution of flares from KIC 5474065 with that of KIC 9726699, which has also been observed using 1 min sampling, and ground based observations of other M dwarf stars …
We present the results of fast spectrophotometry of flares on the RS CVn-type star AR Lac with a time resolution of 34 s and a spectroscopic resolution R $\sim $ 1300. The observations were performed on July 21-22, 2021 with the 2.0 m Karl Zeiss telescope at the Terskol Observatory. During the flares, an additional emission appeared in the spectrum of AR Lac at wavelengths nearby Ca II H\&K ($λ$ = 3933, 3968 Å), nearby Si IV lines ($λ$ = 4089, 4116 Å). Variations in these lines range from 2 to 5\%. We have estimated the UBV magnitudes from spectrograms through a mathematical convolution of the…
One way of imaging X-ray emission from solar flares is to measure Fourier components of the spatial X-ray source distribution. We present a new Compressed Sensing-based algorithm named VIS_CS, which reconstructs the spatial distribution from such Fourier components. We demonstrate the application of the algorithm on synthetic and observed solar flare X-ray data from the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) satellite and compare its performance with existing algorithms. VIS_CS produces competitive results with accurate photometry and morphology, without requiring any al…
We analyzed the light curves of 1376 early-to-late, nearby M dwarfs to search for white-light flares using photometry from the All-Sky Automated Survey for Supernovae (ASAS-SN). We identified 480 M dwarfs with at least one potential flare employing a simple statistical algorithm that searches for sudden increases in $V$-band flux. After more detailed evaluation, we identified 62 individual flares on 62 stars. The event amplitudes range from $0.12 <ΔV < 2.04$ mag. Using classical-flare models, we place lower limits on the flare energies and obtain $V$-band energies spanning $2.0\times10^{30} \l…
The near-ultraviolet and optical (white-light) continuum radiation in M dwarf flares exhibits a range of observed characteristics, suggesting that the amount of heating at large optical depth varies among impulsive-type and gradual-type flares. Specific flux ratios from high-time cadence spectra and narrowband continuum photometry have also shown that these characteristics vary from the peak to the gradual decay phases of flares. In these proceedings, we present the highest-time cadence ($\sim1$~s), highest signal-to-noise ($\sim100$) constraints on the optical color temperature evolution duri…
Gaia method paper: an algorithm to detect flare events in Gaia time-series
INAF - Osservatorio Astrofisico di Catania（意大利国家天体物理研究所卡塔尼亚天文台）；University of Catania, Astrophysics Section, Dept. of Physics and Astronomy（卡塔尼亚大学天体物理系）；Department of Astronomy, University of Geneva（日内瓦大学天文学系）；Sednai Sàrl（Sednai有限公司）
We present the discovery of a relationship between the maximum ratio of the flare flux (namely, 0.5-4 Ang to the 1-8 Ang flux) and non-flare background (namely, the 1-8 Ang background flux), which clearly separates flares into classes by peak flux level. We established this relationship based on an analysis of the Geostationary Operational Environmental Satellites (GOES) X-ray observations of ~ 50,000 X, M, C, and B flares derived from the NOAA/SWPC flares catalog. Employing a combination of machine learning techniques (K-nearest neighbors and nearest-centroid algorithms) we show a separation …
We present a comprehensive study of the active dM4e star GJ 1243. We use previous observations and ground-based echelle spectroscopy to determine that GJ 1243 is a member of the Argus association of field stars, suggesting it is $\sim 30-50$ Myr old. We analyze eleven months of 1-minute cadence data from Kepler, presenting Kepler flare frequency distributions, as well as determining correlations between flare energy, amplitude, duration, and decay time. We find that the exponent $α$ of the power-law flare energy distribution varies in time, primarily due to completeness of sample and the low f…
Solar flares are one of the most energetic events in the solar system, their impact on Earth at ground level and its atmosphere remains under study. The repercussions of this phenomenon in our technological infrastructure includes radio blackouts and errors in geopositional and navigation systems that are considered natural hazards in ever more countries. Occurrence frequency and intensity of the most energetic solar flares are been taken into account in national programs for civil protection in order to reduce the risk and increase the resilience from Space Weather events. In this work we use…
University of Graz（格拉茨大学）；Astronomical Institute of the Czech Academy of Sciences（捷克科学院天文研究所）；RG Science（RG科学）；Astronomical Institute of Charles University（查理大学天文研究所）；Center of Scientific Excellence - Solar and Stellar Activity, University of Wrocław（弗罗茨瓦夫大学卓越科学中心-太阳与恒星活动）；Thüringer Landessternwarte Tautenburg（图林根州陶滕堡国立天文台）
COBALT-BLUE: a fast and accurate model for gravitational self-lensing binary systems
Newcastle University（纽卡斯尔大学）；Durham University（杜伦大学）；University of Southampton（南安普顿大学）；Nicolaus Copernicus Astronomical Center, Polish Academy of Sciences（波兰科学院尼古拉·哥白尼天文学中心）；The Open University（开放大学）；Michigan State University（密歇根州立大学）；University of Washington（华盛顿大学）
During our optical monitoring of UV Ceti, iconic late-type flaring star, with high temporal resolution using the Russian 6-m telescope in 2008 we detected a giant flare with the amplitude of about 3 magnitudes in $U$-band. Near flare maximum more than a dozen of spike bursts have been discovered with triangular shapes and durations from 0.6 to 1.2 s and maximal luminosities in the range $(1.5-8)\times10^{27}$ erg~s$^{-1}$. For the half of these events the linear polarization exceeds 35% with significance better than $5σ$. We argue that these events are synchrotron emission of electron streams …
The presence and strength of a stellar magnetic field and activity is rooted in a star's fundamental parameters such as mass and age. Can flares serve as an accurate stellar "clock"? To explore if we can quantify an activity-age relation in the form of a flaring-age relation, we measured trends in the flaring rates and energies for stars with different masses and ages. We investigated the time-domain photometry provided by Kepler's follow-up mission K2 and searched for flares in three solar metallicity open clusters with well-known ages, M45 (0.125 Gyr), M44 (0.63 Gyr), and M67 (4.3 Gyr). We u…
We present more than 1000-day long photometry of EY Draconis in BV(RI)C passbands. The changes in the light curve are caused by the spottedness of the rotating surface. Modelling of the spotted surface shows that there are two large active regions present on the star on the opposite hemispheres. The evolution of the surface patterns suggests a flip-flop phenomenon. Using Fourier analysis, we detect a rotation period of P_rot=0.45875d, and an activity cycle with P~350d, similar to the 11-year long cycle of the Sun. This cycle with its year-long period is the shortest one ever detected on active…
Using the wealth of ~24 yr multiband data, we present an in-depth study of the star-spot cycles, surface differential rotations (SDR), optical flares, evolution of star-spot distributions, and coronal activities on the surface of young, single, main-sequence, ultrafast rotator (UFR) LO Peg. From the long-term V -band photometry, we derive rotational period of LO Peg to be 0.4231 +/- 0.0001 d. Using the seasonal variations on the rotational period, the SDR pattern is investigated, and shows a solar-like pattern of SDR. A cyclic pattern with period of ~2.7 yr appears to be present in rotational …
Statistically analyzing Johnson UBVR observations of V1285 Aql during the three observing seasons, both activity level and behavior of the star are discussed in respect to obtained results. We also discuss the out-of-flare variation due to rotational modulation. Eighty-three flares were detected in the U-band observations of season 2006 . First, depending on statistical analyses using the independent samples t-test, the flares were divided into two classes as the fast and the slow flares. According to the results of the test, there is a difference of about 73 s between the flare-equivalent dur…
During the next solar maximum, two upcoming space-borne X-ray missions, STIX on board Solar Orbiter and MiSolFA, will perform stereoscopic X-ray observations of solar flares at two different locations: STIX at 0.28 AU (at perihelion) and up to inclinations of $\sim25^{\circ}$, and MiSolFA in a low-Earth orbit. The combined observations from these cross-calibrated detectors will allow us to infer the electron anisotropy of individual flares confidently for the first time. We simulated both instrumental and physical effects for STIX and MiSolFA including thermal shielding, background and X-ray C…
In this study, new observations and some results of statistical analyses are presented. The largest flare data set of DO Cep in the literature has been obtained with 89 flares detected in 67.61 hours of U-band flare patrol. First of all, the observations demonstrated that the star is one of the most active flare stars in respect to the computed flare frequency. Secondly, using the independent samples t-test, the detected flares were classified into two subtypes, and then they were modelled. Analysing the models demonstrated that the fast and slow flares occurring on the star can be separated w…
AE Aqr objects are a class of cataclysmic variable stars in which the rapidly rotating magnetosphere of the white dwarf (WD) primary centrifugally expels most infalling gas before it can accrete onto the WD. The expulsion of the accretion flow via this "magnetic propeller" extracts angular momentum from the WD and produces large-amplitude, aperiodic flares in optical photometry. The eponymous AE Aqr is the only confirmed member of this class of object, but recently, Thorstensen (2020) discovered a candidate AE Aqr system: LAMOST J024048.51+195226.9. Using survey photometry, we measure a refine…
The All-Sky Automated Survey for Supernovae (ASAS-SN) is the only project in existence to scan the entire sky in optical light every $\sim$day, reaching a depth of $g\sim18$ mag. Over the course of its first four years of transient alerts (2013-2016), ASAS-SN observed 53 events classified as likely M dwarf flares. We present follow-up photometry and spectroscopy of all 53 candidates, confirming flare events on 47 M dwarfs, one K dwarf, and one L dwarf. The remaining four objects include a previously identified TT Tauri star, a young star with outbursts, and two objects too faint to confirm. A …
We report the observation on UT 2017.07.01 of an unusually powerful flare detected in near-infrared continuum photometry of Proxima Centauri. During a campaign monitoring the star for possible exoplanet transits, we identified an increase in Sloan i' flux leading to an observed peak at BJD 2457935.996 that was at least 10\% over pre-flare flux in this band. It was followed by a 2-component rapid decline in the first 100 seconds that became a slower exponential decay with time constant of 1350 seconds. A smaller flare event 1300 seconds after the first added an incremental peak flux increase of…
Cycle Variation in the Occurrence of Great Soft X-ray Solar Flares
Sternberg Astronomical Institute, Lomonosov Moscow State University（列莫诺索夫莫斯科国立大学斯腾伯格天文研究所）；Department of Physics, Lomonosov Moscow State University（列莫诺索夫莫斯科国立大学物理系）
X-ray emission from Young Stellar Objects (YSOs) is crucial to understand star formation. A very limited amount of X-ray results is available for the protostellar (ClassI) phase. A systematic search of transient X-ray phenomena combined with a careful evaluation of the evolutionary stage offer a widely unexplored window to our understanding of YSOs X-ray properties. Within the EXTraS project, a search for transients and variability in the whole XMM-Newton archive, we discover transient X-ray emission consistent with ISO-Oph 85, a strongly embedded YSO in the rho Ophiuchi region, not detected i…
The solar Lyα line emission can be considered as the dominant source of ionization processes in the ionospheric D-region at altitudes above 70 km during unperturbed conditions. However, large sudden impacts of radiation in some other energy domains can also significantly influence the ionization rate and, in this paper, we present a study on the contribution of Ly α radiation to the ionization rate when the ionosphere is disturbed by solar X-flares. We give relevant analytical expressions and make calculations and numerical simulations for the low ionosphere using data collected by the VLF rec…
We investigate the evolution of differential emission measure distribution (DEM[T]) in various phases of a B8.3 flare, which occurred on July 04, 2009. We analyze the soft X-ray (SXR) emission in 1.6-8.0 keV range, recorded collectively by Solar Photometer in X-rays (SphinX; Polish) and Solar X-ray Spectrometer (SOXS; Indian) instruments. We make a comparative investigation of the best-fit DEM[T] distributions derived by employing various inversion schemes viz. single gaussian, power-law, functions and Withbroe-Sylwester (W-S) maximum likelihood algorithm. In addition, SXR spectrum in three di…
The flare activity and the ultraviolet emission of the sun during its 24-th cycle are analysed. As compared to cycles 21-23, where the most powerful flares were observed during the decay phase, in cycle 24 the greatest number of powerful flares (>X2.7) occurred in the rising phase and at the maximum with the exception of the two largest flares of cycle 24 X9.3 and X8.2 in September 2017. We showed that regression fits of solar UV indices to the overall radiation level from the sun are substantially different for cycle 24 compared to cycles 21-23. It is found that for the flare of August 9, 201…
Stellar flares with Ariel: detection prospects and impacts on exoplanet spectroscopy
Konkoly Observatory（孔科利天文台）；HUN-REN Research Centre for Astronomy and Earth Sciences（匈牙利研究网络地球与天文学研究中心）；HUN-REN CSFK MTA Centre of Excellence（匈牙利研究网络 CSFK 马塔科学院卓越中心）；SRON Space Research Organisation Netherlands（荷兰空间研究组织 SRON）
In this paper, the energy budgets of two single-loop like flares observed in X- ray are analysed under the assumption that non-thermal electrons (NTEs) are the only source of plasma heating during all phases of both events. The flares were observed by RHESSI and GOES on February 20th, 2002 and June 2nd, 2002, respectively. Using a 1D hydrodynamic code for both flares the energy deposited in the chromosphere was derived applying RHESSI observational data. The use of the Fokker-Planck formalism permits the calculation of distributions of the NTEs in flaring loops, thus spatial distributions of t…
As more exoplanets are being discovered around ultracool dwarfs, understanding their magnetic activity -- and the implications for habitability -- is of prime importance. To find stellar flares and photometric signatures related to starspots, continuous monitoring is necessary, which can be achieved with spaceborn observatories like the Transiting Exoplanet Survey Satellite (TESS). We present an analysis of TRAPPIST-1 like ultracool dwarfs with TESS full-frame image photometry from the first two years of the primary mission. A volume-limited sample up to 50 pc is constructed consisting of 339 …
