We investigate the photometric modulation induced by magnetic activity cycles and study the relationship between rotation period and activity cycle(s) in late-type (FGKM) stars. We analyse light-curves spanning up to 9 years of 125 nearby stars provided by the ASAS survey. The sample is mainly conformed by low-activity main sequence late A to mid M-type stars. A search is performed for short (days) and long-term (years) periodic variations in the photometry. We modelled with combinations of sinusoids the light-curves to measure the properties of these periodic signals. To provide a better statistical interpretation of our results we complement them with the results from previous similar works. We have been able to measure long-term photometric cycles of 47 stars. Rotational modulation was also detected and rotational periods measured in 36 stars. For 28 stars we have simultaneous measurements of both, activity cycles and rotational periods, being 17 of them M-type stars. From sinusoidal fits we measured both photometric amplitudes and periods. The measured cycle periods range from 2 up to 14 yr with photometric amplitudes in the range of 5-20 mmag. We have found that the distribution of cycle lengths for the different spectral types is similar. On the other hand the distribution of rotation periods is completely different, trending to longer periods for later type stars. The amplitudes induced by magnetic cycles and rotation show a clear correlation. A trend of photometric amplitudes with rotation period is also outlined in the data. For a given activity index the amplitudes of the photometric variability induced by activity cycles of main sequence GK stars are lower than those of early and mid-M dwarfs. Using spectroscopic data we also provide an update in the empirical relationship between the level of chromospheric activity as given by log(Rhk) and the rotation periods.
We investigate magnetic activity properties of 21 stars via medium resolution optical spectra and long-term photometry. Applying synthetic spectrum fitting method, we find that all targets are cool giant or sub-giant stars possessing overall [M/H] abundances between $0$ and $-0.5$. We find that six of these targets exhibit only linear trend in mean brightness while eight of them clearly shows cyclic mean brightness variation. Remaining seven target appear to exhibit cyclic mean brightness variation but this can not be confirmed due to the long time scales of the predicted cycle compared to the…
Until a few years ago, the amplitude variation in the photometric data had been limitedly explored mainly because of time resolution and photometric sensitivity limitations. This investigation is now possible thanks to the Kepler and CoRoT databases which provided a unique set of data for studying of the nature of stellar variability cycles. The present study characterizes the amplitude variation in a sample of main--sequence stars with light curves collected using CoRoT exo--field CCDs. We analyze potential stellar activity cycles by studying the variability amplitude over small boxes. The cy…
Although chromospheric activity cycles have been studied in a larger number of late-type stars for quite some time, very little is known about coronal activity-cycles in other stars and their similarities or dissimilarities with the solar activity cycle. While it is usually assumed that cyclic activity is present only in stars of low to moderate activity, we investigate whether the ultra-fast rotator AB Dor, a K dwarf exhibiting signs of substantial magnetic activity in essentially all wavelength bands, exhibits a X-ray activity cycle in analogy to its photospheric activity cycle of about 17 y…
The subtype of hot algol semidetached binaries dubbed Double Periodic Variables (DPVs) are characterized by a photometric cycle longer than the orbital one, whose nature has been related to a magnetic dynamo in the donor component controlling the mass transfer rate. We aim to understand the morphologic changes observed in the light curve of OGLE-BLG-ECL-157529 that are linked to the long cycle. In particular, we want to explain the changes in relative depth of primary and secondary eclipses. We analyze $I$ and $V$-band OGLE photometric times series spanning 18.5 years and model the orbital lig…
Long Photometric Cycles in Double Periodic Variables from Nodal Precession of a Tilted Accretion Disk
Yunnan Observatories, Chinese Academy of Sciences（中国科学院云南天文台）；Center for Astronomical Mega-Science, Chinese Academy of Sciences（中国科学院国家天文台）；Key Laboratory for the Structure and Evolution of Celestial Objects, Chinese Academy of Sciences（中国科学院天体结构与演化重点实验室）；University of Chinese Academy of Sciences（中国科学院大学）
Using the phase plane diagrams, the phase light curves of a group of the Mira-type stars and semi-regular variables are analyzed. As generalized coordinates x and $\dot{x}$, we have used m - the brightness of the star and its phase derivative. We have used mean phase light curves using observations of various authors. The data typically span a large time interval (nearly a century). They were compiled from the databases of AAVSO, AFOEV, VSOLJ, ASAS and approximated using a trigonometric polynomial of statistically optimal degree. As the resulting approximation characterizes the auto-oscillatio…
Photometry from the Kepler mission is optimized to detect small, short duration signals like planet transits at the expense of long-term trends. This long-term variability can be recovered in photometry from the Full Frame Images (FFIs), a set of calibration data collected approximately monthly during the Kepler mission. Here, we present f3, an open-source package to perform photometry on the Kepler FFIs in order to detect changes in the brightness of stars in the Kepler field of view over long time baselines. We apply this package to a sample of 4,000 Sun-like stars with measured rotation per…
Solar irradiance variations over solar rotational time-scales are largely determined by the passage of magnetic structures across the visible solar disk. Variations on solar cycle time scales are thought to be similarly due to changes in surface magnetism with activity. Understanding the contribution of magnetic structures to total solar irradiance and solar spectral irradiance requires assessing their contributions as a function of disk position. Since only relative photometry is possible from the ground, the contrasts of image pixels are measured with respect to a center-to-limb intensity pr…
By combining ground-based spectrographic observations of variability in the chromospheric emission from Sun-like stars with the variability seen in their eigenmode frequencies, it is possible to relate the changes observed at the surfaces of these stars to the changes taking place in the interior. By further comparing this variability to changes in the relative flux from the stars, one can obtain an expression for how these activity indicators relate to the energy output from the stars. Such studies become very pertinent when the variability can be related to stellar cycles as they can then be…
In recent years it has been claimed that the length of stellar activity cycles is determined by the stellar rotation rate. It is observed that the cycle period increases with rotation period along the so-called active and inactive sequences. In this picture the Sun occupies a solitary position in between the two sequences. Our goal is to measure cyclic variations of the stellar light curve amplitude and the rotation period using four years of Kepler data. Periodic changes of the light curve amplitude or the stellar rotation period are associated with an underlying activity cycle. Using the McQ…
We report new photometric observations of the 200000 year old naked weak-line run-away T Tauri star Par 1724, located north of the Trapezium cluster in Orion. We observed in the broad band filters B, V, R, and I using the 90cm Dutch telescope on La Silla, the 80cm Wendelstein telescope, and a 25cm telescope of the University Observatory Jena in Grossschwabhausen near Jena. The photometric data in V and R are consistent with a 5.7 day rotation period due to spots, as observed before between 1960ies and 2000. Also, for the first time, we present evidence for a long-term 9 or 17.5 year cycle in p…
We analyze the effect of solar features on the variability of the solar irradiance in three different spectral ranges. Our study is based on two solar-cycles' worth of full-disk photometric images from the San Fernando Observatory, obtained with red, blue and Ca II K-line filters. For each image we measure the photometric sum, Sigma, which is the relative contribution of solar features to the disk-integrated intensity of the image. The photometric sums in the red and blue continuum, Sigma_r and Sigma_b, exhibit similar temporal patterns: they are negatively correlated with solar activity, with…
We present the discovery of 32 new double periodic variables (DPVs) located toward the Galactic bulge. We found these objects among the nearly half a million binary stars published by the Optical Gravitational Lensing Experiment project. With this discovery, we increase the number of known DPVs in the Milky Way by a factor of 2. The new set of DPVs contains 31 eclipsing binaries and one ellipsoidal variable star. The orbital periods cover the range from 1.6 to 26 days, while long periods are detected between 47 and 1144 days. Our analysis confirms a known correlation between orbital and long p…
Modern databases and rows of observations allow to make progress in study of magnetic activity of solar-type stars and cold dwarfs. Digitizing of wide-filed plates in the large archives give historical data expanding the investigated time intervals up to century. Photometric sources for a seek and study of cycles produced by starspots are considered and results for several red dwarfs are presented.
We present photometric and spectroscopic observations of the cataclysmic variable MASTER OT J132104.04+560957.8 which strongly indicate that it is a polar with an orbital period of 91 minutes. The optical light curve shows two maxima and two minima per orbital cycle, with considerable variation in the strength of the secondary maximum and in the morphology and depth of the minima.
We present synthetic broad-band photometric colors of a late-type giant located close to the RGB tip (T_eff = 3640 K, log g = 1.0 and [M/H] = 0.0). Johnson-Cousins-Glass BVRIJHK colors were obtained from the spectral energy distributions calculated using 3D hydrodynamical and 1D classical stellar atmosphere models. The differences between photometric magnitudes and colors predicted by the two types of models are significant, especially at optical wavelengths where they may reach, e.g., ΔV~0.16, ΔR~0.13 and Δ(V-I)~0.14, Δ(V-K)~0.20. Differences in the near-infrared are smaller but still non-neg…
We introduce the class of intermediate mass binaries named Double Periodic Variables (DPVs), characterized by orbital photometric variability (ellipsoidal or eclipsing) in time scales of few days and a long photometric cycle lasting roughly 33 times the orbital period. After a search conducted in the OGLE and ASAS catalogues, we identified 114 of these systems in the Magellanic Clouds and 11 in the Galaxy. We present results of our photometric and spectroscopic campaigns on DPVs conducted during the last years, outlining their main observational characteristics. We present convincing evidence …
Spectroscopic and Decade-long Photometric Observations of the Contact Binary V2790 Ori: Evidence for a Brown Dwarf Companion and a Solar-like Magnetic Activity Cycle
Long-term photometric measurements in a sample of ultrashort-period (P~0.5 days or less) single and binary stars of different interior structures are analysed. A loose correlation exists between the rotational rate and cycle lengths of active stars, regardless of their evolutionary state and the corresponding physical parameters. The shortest cycles are expected on the fastest rotators in the order of 1-2 years, which is reported in this paper.
The Rome Precision Solar Photometric Telescope (Rome/PSPT) is a ground-based telescope engaged in precision solar photometry. It has a 27-year database of full-disk images of the photosphere and chromosphere beginning in 1996 and continuing to 2022. The solar images have been obtained daily, weather permitting, with approximately 2 arcsec/pixel scale in Ca II K line at 393.3 nm, G-band at 430.6 nm, and continuum in the blue and red parts of the spectrum at 409.4 nm and 607.2 nm, respectively. Regular observations were also performed at the green continuum at 535.7 nm for a period of about 18 m…
We present CCD photometric observations of the W UMa type contact binary EK Comae Berenices using the 2 metre telescope of $IUCAA$ Girawali Observatory, India. The star was classified as a W UMa type binary of subtype-W by \citet{sam1996}. The new V band photometric observations of the star reveal that shape of the light curve has changed significantly from the one observed by \citet{sam1996}. A detailed analysis of the light curve obtained from the high-precision CCD photometric observations of the star indicates that EK Comae Berenices is not a W-type but an A-type totally eclipsing W UMa co…
DK Cyg (P = 0.4707) is a W Ursae Majoris type eclipsing binary system that undergoes complete eclipses. All the published photoelectric data have been collected and utilized to re-examine and update the period behavior of the system. A significant period increase with rate of 12.590x10-11 day/cycle was calculated. New period and ephemeris has been calculated for the system. A long term photometric solution study was performed and a light curve elements were calculated. We investigated the evolutionary status of the system using theoretical evolutionary models.
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.
Miras are fascinating stars. A kappa-mechanism in their atmosphere drives pulsations which produce changes in their photometric brightness, apparent spectral type and effective temperature. These pulsations also drive the formation of Balmer emission lines in the spectrum. This behaviour can be observed and investigated with small telescopes. We report on a three-year project combining spectroscopy and photometry to analyse the behaviour of Mira stars SU Cam and RY Cep, and describe how their brightness, colour, spectral type, effective temperature and Balmer emission vary over four pulsation …
V473 Lyrae is the only Galactic Cepheid with confirmed periodic amplitude and phase variations similar to the Blazhko effect observed in RR Lyrae stars. We collected all available photometric data and some radial velocity measurements to investigate the nature of the modulation. The comparison of the photometric and radial velocity amplitudes confirmed that the star pulsates in the second overtone. The extensive data set, spanning more than 40 years, allowed us to detect a secondary modulation cycle with a period of approximately 5300 days or 14.5 years. The secondary variations can be detecte…
The current photometric datasets, that span decades, allow for studying long-term cycles on active stars. Complementary Ca H&K observations give information also on the cycles of normal solar-like stars, which have significantly smaller, and less easily detectable, spots. In the recent years, high precision space-based observations, for example from the Kepler satellite, have allowed also to study the sunspot-like spot sizes in other stars. Here I review what is known about the properties of the cyclic stellar activity in other stars than our Sun.
Using data of fast-rotating active dwarf stars in the Kepler database, we perform time-frequency analysis of the light curves in order to search for signs of activity cycles. We use the phenomenon that the active region latitudes vary with the cycle (like the solar butterfly diagram), which causes the observed rotation period to change as a consequence of differential rotation. We find cycles in 8 cases of the 39 promising targets with periods between of 300-900 days.
We analyse light curves covering four years of 39 fast-rotating ($P_\mathrm{rot}< 1d$) late-type active stars from the Kepler database. Using time-frequency analysis (Short-Term Fourier-Transform), we find hints for activity cycles of 300-900 days at 9 targets from the changing typical latitude of the starspots, which, with the differential rotation of the stellar surface change the observed rotation period over the activity cycle. We also give a lowest estimation for the shear parameter of the differential rotation, which is ~0.001 for the cycling targets. These results populate the less stud…
We study the variability of solar activity using new photospheric proxies originally developed for the analysis of stellar magnetism with the CoRoT and Kepler photometric observations. These proxies are obtained by tracking the temporal modulations in the observations associated to the spots and magnetic features as the Sun rotates. We analyze here 21 years, spanning solar cycles 23 and 24, of the observations collected by the space-based photometric VIRGO and radial velocity GOLF instruments on board the SoHO satellite. The photospheric activity proxy Sph is then calculated for each of the th…
OGLE-LMC-DPV-065 is an interacting binary whose double-hump long photometric cycle remains hitherto unexplained. We analyze photometric time series available in archive datasets spanning 124 years and present the analysis of new high-resolution spectra. A refined orbital period is found of 10\fd0316267 $\pm$ 0\fd0000056 without any evidence of variability. In spite of this constancy, small but significant changes in timings of the secondary eclipse are detected. We show that the long period continuously decreases from 350 to 218 days during 13 years, then remains almost constant for about 10 y…
We study the time variations of the cycles of 20 active stars based on decades-long photometric or spectroscopic observations. A method of time-frequency analysis, as discussed in a companion paper, is applied to the data. Fifteen stars definitely show multiple cycles; the records of the rest are too short to verify a timescale for a second cycle. The cycles typically show systematic changes. For three stars, we found two cycles in each of them that are not harmonics, and which vary in parallel, indicating that a common physical mechanism arising from a dynamo construct. The positive relation …
We present the results of our $UBV$ and $JHKLM$-photometry for the semiregular pulsating variable V1027~Cyg, a supergiant with an infrared excess, over the period from 1991 to 2015. Our search for a periodicity in the $UBV$ brightness variations has led to several periods from $P=212^{d}$ to $P=320^{d}$ in different time intervals. We have found the period $P=237^{d}$ based on our infrared photometry. The variability amplitude, the light-curve shape, and the magnitude of V1027~Cyg at maximum light change noticeably from cycle to cycle. An ambiguous correlation of the $B-V$ and $U-B$ colors wit…
We present colour transformations from Two Micron All Sky Survey (2MASS) photometric system to Johnson-Cousins system and to Sloan Digital Sky Survey (SDSS) system for late-type giants and vice versa. The giant star sample was formed using surface gravity constraints ($2 < \log g \leq 3$) to Cayrel de Strobel et al.\rq s (2001) spectroscopic catalogue. 2MASS, SDSS and Johnson-Cousins photometric data was taken from Cutri et al. (2003), Ofek (2008) and van Leeuwen (2007), respectively. The final sample was refined applying the following steps: (1) the data were dereddened, (2) the sample stars …
We compile a list of 121 RS CVn type stars from the bibliography in southern hemisphere, to search for activity cycles, covering a large range of luminosities and rotation periods. For each system of the list, we obtain photometric data from the All Sky Automated Survey (ASAS), and we complement it with our own photometry, obtained with the Optical Robotic Observatory (ORO). We analyze this data with the Generalized Lomb-Scargle periodogram to determine the rotation period and possible activity cycles for each system. We found rotation periods for 102 systems and activity cycles for 91 systems…
Magnetic cycles have been detected in tens of solar-like stars. The relationship between the cycle properties and global stellar parameters is not fully understood yet. We searched for activity cycles in 90 solar-like stars with ages between 4 and 95 Myr aiming to investigate the properties of activity cycles in this age range. We measured the length $P_{ cyc}$ of a given cycle by analyzing the long-term time-series of three activity indexes. For each star, we computed also the global magnetic activity index <IQR> that is proportional to the amplitude of the rotational modulation and is a prox…
We present an analysis of long-term photometric variability for nearby red dwarfs at optical wavelengths. The sample consists of 264 M dwarfs south of DEC = +30 with V-K = 3.96-9.16 and Mv~10-20 (spectral types M2V-M8V), most of which are within 25 pc. The stars have been observed in the VRI filters for ~4-14 years at the CTIO/SMARTS 0.9m telescope. Of the 238 red dwarfs within 25 pc, we find that only ~8% are photometrically variable by at least 20 mmag (~2%) in the VRI bands. We find that high variability at optical wavelengths over the long-term can be used to identify young stars. Overall,…
The new multi-color $BVRI$ photometric light curves of the short-period eclipsing binary GSC 3576-0170 were obtained on two consecutive nights (October 5 and 6, 2009). With the 2003 version of Wilson-Devinney program, the precise photometric solutions are derived for the first time. The result shows that GSC 3576-0170 is a semi-detached binary system with a large temperature difference of approximately 1490 K. The light-curve distortions are further explained by a hot spot on the secondary component through mass transfer via a stream hitting the facing surface of the secondary component. By an…
We report time-resolved photometry of the cataclysmic variable V849 Her, and measure a period of 0.1414 \pm 0.0030 days (3.394 \pm 0.072 hours). We also present photometry taken over several weeks in 2010 and 2011, as well as light curves from 1995 to 2011 by the American Association of Variable Star Observers. The spectra, absolute magnitude derived from infrared magnitudes, and variability all suggest that V849 Her is a nova-like variable. The shallow (0.5-magnitude) low states we observe resemble the erratic low states of the VY Sculptoris stars, although they may recur quasi-periodically o…
Here, BV(RI)c broad band photometry and intermediate resolution spectroscopy in Halpha region are presented for two rapidly rotating late-type stars: EY Dra and V374 Peg. For a third rapid rotator, GSC 02038-00293, intermediate resolution Halpha spectroscopy and low resolution spectroscopy are used for spectral classification and stellar parameter investigation of this poorly known object. The low resolution spectrum of GSC 02038-00293 clearly indicates that it is a K-type star. Its intermediate resolution spectrum can be best fitted with a model with Teff=4750K and vsini=90km/s, indicating a …
The VRI light curves were measured for the low-mass eclipsing binary V608 Cam as a part of our long-term observational project for studying of eclipsing binaries with a short orbital period. The Tess light curve solution in Phoebe results to the detached configuration, where the temperature of primary component was fixed to $T_1 = 5300$ K according to Gaia results, which gives us $T_2 = 4110 \pm 50$ K for the secondary. The spectral type of the primary component was derived to be K0 and the photometric mass ratio was estimated $q = 0.92 \pm 0.07$. Characteristics and temporal variation of the …
Astrometry from Gaia will measure the positions of stellar photometric centroids to unprecedented precision. We show that the precision of Gaia astrometry is sufficient to detect starspot-induced centroid jitter for nearby stars in the Tycho-Gaia Astrometric Solution (TGAS) sample with magnetic activity similar to the young G-star KIC 7174505 or the active M4 dwarf GJ 1243, but is insufficient to measure centroid jitter for stars with Sun-like spot distributions. We simulate Gaia observations of stars with 10 year activity cycles to search for evidence of activity cycles, and find that Gaia as…
II UMa is a late F-type (F5) contact binary with a close-in tertiary and a distant visual companion. According to the four-color ($B$ $V$ $R_c$ $I_c$) light curves' solutions of II UMa, it is a high fill-out (f=$86.6\,\%$) and low mass ratio ($q = 0.172$) contact binary system, which indicate that it is at the late evolutionary stage of late-type tidal-locked binary stars. The mass of the primary star and secondary one are calculated to be $M_1 = 1.99M_\odot$, $M_2 = 0.34M_\odot$. The primary star has evolved from ZAMS, but it is still before TAMS, and the secondary star is even more evolved. …
We analyse the spectroscopic and photometric variability of the Oe star HD 60848 over the last twenty five years. The spectra reveal recurrent, but irregular cycles of increased circumstellar emission lines. These cycles are highly asymmetric displaying a slow increase over about 6 years, followed by a fast decay within about 6 months. Our analysis focuses on the most recent cycle (2013 - 2020). The equivalent width and velocity separation of the emission peaks indicate variations of the outer disk radius by a factor ~ 2.2, although the variability appears more complex than expected from first…
We present time series photometric and spectroscopic data for the transient SN 2009ip from the start of its outburst in September 2012 until November 2013. This data was collected primarily with the new robotic capabilities of the Las Cumbres Observatory Global Telescope Network, a specialized facility for time domain astrophysics, and includes supporting high-resolution spectroscopy from the Southern Astrophysical Research Telescope, Kitt Peak National Observatory, and Gemini Observatory. Based on our nightly photometric monitoring, we interpret the strength and timing of fluctuations in the …
We present the Late-Type Extension to the Motion Verified Red Stars (LaTE-MoVeRS) catalog, containing 46,463 photometric late-type ($>$ M5) dwarfs within the Sloan Digital Sky Survey (SDSS) footprint. Proper motions were computed for objects combining astrometry from the SDSS Data Release 12 (DR12), the Two-Micron All-Sky Survey (2MASS) Point Source Catalog (PSC), and the \emph{Wide-field Infrared Survey Explorer} (\emph{WISE}) AllWISE datasets. LaTE-MoVeRS objects were required to have significant proper motion ($μ_\mathrm{tot} \geqslant 2σ_{μ_\mathrm{tot}}$). Using the LaTE-MoVeRS sample and…
The study of stellar activity cycles is crucial to understand the underlying dynamo and how it causes activity signatures such as dark spots and bright faculae. We study the appearance of activity signatures in contemporaneous photometric and chromospheric time series. Lomb-Scargle periodograms are used to search for cycle periods present in both time series. To emphasize the signature of the activity cycle we account for rotation-induced scatter in both data sets by fitting a quasi-periodic Gaussian process model to each observing season. After subtracting the rotational variability, cycle am…
We present TESS photometry of the asynchronous polar BY Cam, which undergoes a beat-cycle between the 199.384-min white dwarf (WD) spin period and the 201.244-min orbital period. This results in changes in the flow of matter onto the WD. The TESS light curve covers 92% of the beat cycle once and 71% of the beat cycle twice. The strongest photometric signal, at 197.560-min, is ascribed to a side-band period. During times of light-curve stability, the photometry modulates at the spin frequency, supporting our WD spin-period identification. Both one-pole and two-pole accretion configurations repe…
Context: A detailed study of the close interacting binary V4142\,Sgr based on photometric and spectroscopic analysis is presented.This system belongs to the enigmatic class of Algol-like variables showing a long photometric cycle of unknown nature. Aims: Performing photometric data-mining and spectroscopic observations covering the orbital cycle, we obtain the orbital parameters and the stellar properties of the binary system, along with the physical properties of the accretion disk located around the hot star. Insights on the evolutive path of the system are obtained. Methods: The light curve…
Recent photometric results have identified a new population among globular cluster stars. This population, referred to as the ``extended P1'', has been suggested to be the manifestation of a new abundance pattern where the initial mass fraction of He changes among cluster stars that share the same CNO values. The current paradigm for the formation of the multiple stellar populations in globular clusters assumes that variations in He are the product of chemical ``enrichment'' by the ashes of the CNO-cycle (which changes He and other elements like C, N and O simultaneously). We obtained MIKE@Mag…
The known FU Ori-type young eruptive stars are exceedingly rare (a dozen or so confirmed objects) and 2MASS J06593158-0405277, with its 2014 outburst, is likely the latest addition to the family. All members have displayed just one such eruption in their recorded history, an event lasting for decades. To test the FU Ori nature of 2MASS J06593158-0405277, we have reconstructed its photometric history by measuring its brightness on Harvard photographic plates spanning the time interval 1899-1989. No previous large amplitude eruption similar to that initiated in 2014 has been found, as in bona fi…
