Publications (94)
SN 2023ixf in M101: physical parameters from bolometric light curve modeling
J. Vinko, Zs. R. Bodola, A. Godeny +25
We present new photometric observations of the core-collapse supernova SN 2023ixf occurred in M101, taken with the RC80 and BRC80 robotic telescopes in Hungary. The initial nickel…
The strange close binary V405 And: the influence of different dynamos on the components
K. Vida, L. Kriskovics, K. Oláh +1
V405 And is a fast-rotating (P=0.465d) grazing eclipsing binary with two active components. Using multicolor photometric monitoring and radial velocity measurements, we find that t…
Exploring the circumstellar environment of the young eruptive star V2492 Cyg
Ã. Kóspál, P. Ãbrahám, J. A. Acosta-Pulido +20
Context. V2492 Cyg is a young eruptive star that went into outburst in 2010. The near-infrared color changes observed since the outburst peak suggest that the source belongs to a n…
Improved distance determination to M51 from supernovae 2011dh and 2005cs
J. Vinko, K. Takats, T. Szalai +9
The appearance of two recent supernovae, SN 2011dh and 2005cs, both in M51, provides an opportunity to derive an improved distance to their host galaxy by combining the observation…
Detecting coronal mass ejections with machine learning methods
K. Vida, B. Seli, T. Szklenár +3
Flares on the Sun are often associated with ejected plasma: these events are known as coronal mass ejections (CMEs). These events, although are studied in detail on the Sun, have o…
The Konkoly Blazhko Survey: Is light-curve modulation a common property of RRab stars?
J. Jurcsik, Ã. Sódor, B. Szeidl +9
A systematic survey to establish the true incidence rate of the Blazhko modulation among short-period, fundamental-mode, Galactic field RR Lyrae stars has been accomplished. The Ko…
Optical flares from the faint mid-dM star 2MASS J00453911+4140396
Zs. KÅvári, F. Vilardell, I. Ribas +4
We present and light curves of a large stellar flare obtained with the Wide Field Camera at the Isaac Newton 2.5-m telescope (La Palma). The source object is a faint ($m_V=…
Results of the photometry of the spotted dM1-2e star EY Draconis
K. Vida
We have observed EY Draconis with the 24`` telescope of Konkoly Observatory in Budapest for 64 nights. In the first obse rving season the star produced a stable light curve for mor…
An UXor among FUors: extinction related brightness variations of the young eruptive star V582 Aur
P. Ãbrahám, Ã. Kóspál, M. Kun +24
V582 Aur is an FU Ori-type young eruptive star in outburst since 1985. The eruption is currently in a relatively constant plateau phase, with photometric and spectroscopic va…
The outburst and nature of two young eruptive stars in the North America/Pelican Nebula Complex
Ã. Kóspál, P. Ãbrahám, J. A. Acosta-Pulido +8
Context. In August 2010, the sudden optical brightening of two young stellar objects, located in the North America/Pelican Nebula Complex, was announced. Early observations indicat…
Time-series Doppler images and surface differential rotation of the effectively-single rapidly-rotating K-giant KU Pegasi
Zs. KÅvári, A. Künstler, K. G. Strassmeier +6
According to most stellar dynamo theories, differential rotation (DR) plays a crucial role for the generation of toroidal magnetic fields. Numerical models predict surface differen…
The big sibling of AU Mic: a cold dust-rich debris disk around CP-72 2713 in the Pic moving group
A. Moór, N. Pawellek, P. Ãbrahám +8
Analyzing Spitzer and Herschel archival measurements we identified a debris disk around the young K7/M0 star CP-72 2713. The system belongs to the 24Myr old Pic moving group.…
Four decades of photometry of XX Trianguli, `the most spotted star' in the sky
Zs. KÅvári, K. G. Strassmeier, K. Oláh +3
Over the past 40 years the brightness variations of XX Tri, a single line RS CVn type binary system with a synchronized K-giant primary, has exceeded one magnitude in the V band. A…
Photometric and spectroscopic observations of three rapidly rotating late-type stars: EY Dra, V374 Peg and GSC 02038-00293
H. Korhonen, K. Vida, M. Husarik +3
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 thi…
A study of the photometric and spectroscopic variations of the prototypical FU Orionis-type star V1057 Cyg
Zs. M. Szabó, Ã. Kóspál, P. Ãbrahám +19
Among the low-mass pre-main sequence stars, a small group called FU Orionis-type objects (FUors) are notable for undergoing powerful accretion outbursts. V1057 Cyg, a classical exa…
Chromospheric activity in bright contact binary stars
T. Mitnyan, T. Szalai, A. Bódi +7
Studying chromospheric activity of contact binaries is an important way of revealing the magnetic activity processes of these systems. An efficient but somewhat neglected method fo…
Surface velocity network with anti-solar differential rotation on the active K-giant Geminorum
Zs. Kõvári, J. Bartus, M. Švanda +4
We demonstrate the power of the local correlation tracking technique on stellar data for the first time. We recover the spot migration pattern of the long-period RS CVn-type binary…
Superflares on the late-type giant KIC 2852961 -- Scaling effect behind flaring at different energy levels
Zs. KÅvári, K. Oláh, M. N. Günther +7
The most powerful superflares reaching 10erg bolometric energy are from giant stars. The mechanism behind flaring is supposed to be the magnetic reconnection, which is close…
Lithium enrichment on the single active K1-giant DI Piscium -- Possible joint origin of differential rotation and Li enrichment
L. Kriskovics, Zs. KÅvári, K. Vida +2
We investigate the surface spot activity of the rapidly rotating, lithium-rich active single K-giant DI Psc to measure the surface differential rotation and understand the mechanis…
Asteroid sizes determined with thermophysical model and stellar occultations
A. Choukroun, A. Marciniak, J. Äurech +165
Context. The sizes of many asteroids, especially slowly rotating, low-amplitude targets, remain poorly constrained due to selection effects. These biases limit the availability of…
Spots, flares, accretion, and obscuration in the pre-main sequence binary DQ Tau
Ã. Kóspál, P. Ãbrahám, G. Zsidi +4
DQ Tau is a young low-mass spectroscopic binary, consisting of two almost equal-mass stars on a 15.8 d period surrounded by a circumbinary disk. Here, we analyze DQ Tau's light cur…
Magnetic activity of the young solar analogue V1358 Ori
L. Kriskovics, Zs. KÅvári, K. Vida +3
Young, fast rotating single stars can show dramatically different magnetic signatures and levels of magnetic activity as compared with the Sun. While losing angular momentum due to…
Planet Hunters X. KIC 8462852 - Where's the Flux?
T. S. Boyajian, D. M. LaCourse, S. A. Rappaport +46
Over the duration of the Kepler mission, KIC8462852 was observed to undergo irregularly shaped, aperiodic dips in flux of up to \%. The dipping activity can last for betwe…
Image-based Classification of Variable Stars: First Results from Optical Gravitational Lensing Experiment Data
T. Szklenár, A. Bódi, D. Tarczay-Nehéz +5
Recently, machine learning methods presented a viable solution for automated classification of image-based data in various research fields and business applications. Scientists req…
Surface evolution in stable magnetic fields: the case of the fully convective dwarf V374 Peg
K. Vida, K. Oláh, Zs. Kovari
We present BV(RI)_C photometric measurements of the dM4-type V374 Peg covering ~430 days. The star has a mass of ~0.28M_Sun, so it is supposed to be fully convective. Previous obse…
Photospheric and chromospheric activity in V405 And: An M dwarf binary with components on the two sides of the full convection limit
K. Vida, K. Oláh, Zs. KÅvári +4
We investigate the fast-rotating (P_orb=P_rot=0.465d), active dwarf binary V405 And (M0V+M5V) using photometric BV(RI)_C and optical spectroscopic data. The light variation is caus…
Investigating magnetic activity in very stable stellar magnetic fields: long-term photometric and spectroscopic study of the fully convective M4 dwarf V374 Peg
K. Vida, L. Kriskovics, K. Oláh +8
The ultrafast-rotating () fully convective single M4 dwarf V374 Peg is a well-known laboratory for studying intense stellar activity in a stable magnet…
Extending the FIP bias sample to magnetically active stars. Challenging the FIP bias paradigm?
B. Seli, K. Oláh, L. Kriskovics +6
The different elemental abundances of the photosphere and the corona are striking features of not only the Sun, but other stars as well. This phenomenon is known as the FIP effect…
Flare stars in nearby Galactic open clusters based on {\it TESS} data
O. Maryeva, K. Bicz, C. Xia +3
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…
The contact binary VW Cephei revisited: surface activity and period variation
T. Mitnyan, A. Bódi, T. Szalai +7
Context. Despite the fact that VW Cephei is one of the well-studied contact binaries in the literature, there is no fully consistent model available that can explain every observed…
The Kep-Cont Mission: Continuing the observation of high-amplitude variable stars in the Kepler field of view
L. Molnár, R. Szabó, K. Kolenberg +7
As a response to the Kepler white paper call, we propose to keep Kepler pointing to its current field of view and continue observing thousands of large amplitude variables (Cepheid…
The shortest modulation period Blazhko RR Lyrae star: SS Cnc
J. Jurcsik, B. Szeidl, Ã. Sódor +6
Extended BV(RI)c CCD observations of SS Cnc, a short period RRab star are presented. Nearly 1400 data points in each band have been obtained spanning over 79 days during the spring…
KIC 2852961 -- a superflaring red monster in the Kepler field
Zs. KÅvári, K. Oláh, M. N. Günther +3
Superflares on giant stars have up to 100,000 times more energy than the high energy solar flares. However, it is disputed, whether scaling up a solar-type dynamo could explain suc…
SN 2018zd: An Unusual Stellar Explosion as Part of the Diverse Type II Supernova Landscape
Jujia Zhang, Xiaofeng Wang, Jozsef Vinko +29
We present extensive observations of SN 2018zd covering the first \,d after the explosion. This SN shows a possible shock-breakout signal \,hr after the explosion…
Antisolar differential rotation of the K1-giant sigma Geminorum revisited
Zs. Kovari, L. Kriskovics, A. Künstler +6
Context. Surface differential rotation and other global surface flows on magnetically active stars are among the observable manifestations of the stellar dynamo working underneath.…
Identifying the Location in the Host Galaxy of the Short GRB 111117A with the Chandra Sub-arcsecond Position
T. Sakamoto, E. Troja, K. Aoki +31
We present our successful Chandra program designed to identify, with sub-arcsecond accuracy, the X-ray afterglow of the short GRB 111117A, which was discovered by Swift and Fermi.…
Extensive Spectroscopy and Photometry of the Type IIP Supernova 2013ej
G. Dhungana, R. Kehoe, J. Vinko +32
We present extensive optical (, , and open CCD) and near-infrared () photometry for the very nearby Type IIP SN ~2013ej extending from +1 to +461 days after…
The Blazhko behaviour of RR Geminorum I - CCD photometric results in 2004
J. Jurcsik, Ã. Sódor, M. Váradi +9
Extended CCD monitoring of RR Gem revealed that it is a Blazhko type RRab star with the shortest Blazhko period (7.23d) and smallest modulation amplitude (Delta Mmax<0.1 mag) curre…
The Exotic Type Ic Broad-Lined Supernova SN 2018gep: Blurring the Line Between Supernovae and Fast Optical Transients
T. A. Pritchard, Katarzyna Bensch, Maryam Modjaz +28
In the last decade a number of rapidly evolving transients have been discovered that are not easily explained by traditional supernovae models. We present optical and UV data on on…
The Blazhko modulation of TV Boo in 2010
G. Hajdu, J. Jurcsik, Ã. Sódor +6
We present the analysis of the multicolour CCD observations in the 2010 season of the Blazhko RRc star TV Boo. TV Boo shows a complex Blazhko modulation dominated by two independen…
A confined dynamo: magnetic activity of the K-dwarf component in the pre-cataclysmic binary system V471 Tauri
Zs. KÅvári, L. Kriskovics, K. Oláh +6
We scrutinize the red dwarf component in the eclipsing binary system V471 Tau in order to unravel relations between different activity layers from the stellar surface through the c…
Gaia 18dvy: a new FUor in the Cygnus OB3 association
E. Szegedi-Elek, P. Ãbrahám, L. Wyrzykowski +59
We present optical-infrared photometric and spectroscopic observations of Gaia18dvy, located in the Cygnus OB3 association at a distance of 1.88 kpc. The object was noted by the Ga…
An extensive photometric study of the Blazhko RR Lyrae star MW Lyr: II. Changes in the physical parameters
J. Jurcsik, Ã. Sódor, B. Szeidl +11
The analysis of the multicolour photometric observations of MW Lyr, a large modulation amplitude Blazhko variable, shows for the first time how the mean global physical parameters…
Four-colour photometry of EY Dra: a study of an ultra-fast rotating active dM1-2e star
K. Vida, K. Oláh, Zs. KÅvári +8
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 o…
Photospheric and chromospheric activity on EY Dra
H. Korhonen, K. Brogaard, K. Holhjem +4
Magnetic activity in the photosphere and chromosphere of the M dwarf EY Dra is studied and possible correlations between the two are investigated using photometric observations in…
An extensive photometric study of the Blazhko RR Lyrae star DM Cyg
J. Jurcsik, Zs. Hurta, A. Sodor +10
DM Cyg, a fundamental mode RRab star was observed in the 2007 and 2008 seasons in the frame of the Konkoly Blazhko Survey. Very small amplitude light curve modulation was detected…
Long-term X-ray variability of the multiple-planet host L 98-59: Hints of an activity cycle
I. Pillitteri, S. Bellotti, S. Benatti +7
High-energy irradiation in X-rays and UV (XUV) can transform the planetary atmospheres through photoevaporation and photochemistry. This is more crucial for M stars, whose habitabl…
Magnetic activity on the young Sun: a case study of EK Draconis
A. Görgei, L. Kriskovics, K. Vida +8
Context. Young, solar analogue stars provide key insights into the early stages of stellar evolution, particularly in terms of magnetic activity and rotation. Their rapid rotation,…
Radio emission from flaring stars and brown dwarfs
K. Perger, B. Seli, K. Vida
Aims. With the aim to reveal the effects of the magnetic field to the multi-band activity of dwarf stars, we search for associated radio emission for an extensive list of 14 915 br…
Near-Infrared and Optical Observations of Type Ic SN2020oi and broad-lined Ic SN2020bvc: Carbon Monoxide, Dust and High-Velocity Supernova Ejecta
J. Rho, A. Evans, T. R. Geballe +33
We present near-infrared and optical observations of the Type Ic Supernova (SN) 2020oi in the galaxy M100 and the broad-lined Type Ic SN2020bvc in UGC 9379, using Gemini, LCO, SOAR…
Pulsational and evolutionary analysis of the double-mode RR Lyrae star BS Com
I. Dekany, G. Kovacs, J. Jurcsik +8
We derive the basic physical parameters of the field double-mode RR Lyrae star BS Com from its observed periods and the requirement of consistency between the pulsational and evolu…
Magnetic activity under tidal influences in the 2+2~hierarchical quadruple system V815 Herculis
Zs. KÅvári, K. G. Strassmeier, L. Kriskovics +5
Tidal forces in close binaries and multiple systems that contain magnetically active component are supposed to influence the operation of magnetic dynamo. Through synchronization t…
Rotation--differential rotation relationships for late-type single and binary stars from Doppler imaging
Zs. KÅvári, K. Oláh, L. Kriskovics +3
From our sample of spotted late-type stars showing surface differential rotation we find that the relationship between the rotation period and the surface shear coefficient $α=ÎÎ…
Magnetic cycles at different ages of stars
K. Oláh, Zs. KÅvári, K. Petrovay +4
We study the different patterns of interannual magnetic variability in stars on or near the lower main sequence, approximately solar-type (G-K dwarf) stars in time series of 36 yea…
Sub-second cadence structure of optical flares on AD Leo
B. Schmercz, B. Seli, K. Vida +4
Stellar flares are sudden brightenings caused by magnetic reconnection and are frequently observed on late-type stars. High-cadence photometry of flares provides valuable insights…
Constraints on the physical properties of Type Ia supernovae from photometry
R. Konyves-Toth, J. Vinko, A. Ordasi +17
We present a photometric study of 17 Type Ia supernovae (SNe) based on multi-color (Bessell BVRI) data taken at Piszkesteto mountain station of Konkoly Observatory, Hungary between…
SN 2016coi/ASASSN-16fp: An example of residual helium in a type Ic supernova?
S. J. Prentice, C. Ashall, P. A. Mazzali +35
The optical observations of Ic-4 supernova (SN) 2016coi/ASASSN-16fp, from to days after explosion, are presented along with analysis of its physical properties.…
Celestial positions in radio and optical
S. Frey, P. Veres, K. Vida
We discuss the importance of the direct link between the most accurate radio and optical reference frames that will become possible with the next-generation space astrometry missio…
Testing SNe Ia distance measurement methods with SN 2011fe
J. Vinko, K. Sarneczky, K. Takats +17
The nearby, bright, almost completely unreddened Type Ia supernova 2011fe in M101 provides a unique opportunity to test both the precision and the accuracy of the extragalactic dis…
Modelling of an eclipsing RS CVn-binary: V405 And
K. Vida, K. Oláh, Zs. KÅvári
V405 And is an ultrafast-rotating (P_rot ~ 0.46 days) eclipsing binary. The system consists of a primary star with radiative core and convective envelope, and a fully convective se…
Absolute Distances to Nearby Type Ia Supernovae via Light Curve Fitting Methods
J. Vinkó, A. Ordasi, T. Szalai +22
We present a comparative study of absolute distances to a sample of very nearby, bright Type Ia supernovae (SNe) derived from high cadence, high signal-to-noise, multi-band photome…
Detecting activity cycles of late-type dwarfs in Kepler data
K. Vida, K. Oláh
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 us…
Multi-wavelength study of the low-luminosity outbursting young star HBC 722
Ã. Kóspál, P. Ãbrahám, J. A. Acosta-Pulido +22
HBC 722 (V2493 Cyg) is a young eruptive star in outburst since 2010. It is an FU Orionis-type object with an atypically low outburst luminosity. Because it was well characterized i…
A new sdO+dM binary with extreme eclipses and reflection effect
A. Derekas, P. Nemeth, J. Southworth +10
We report the discovery of a new totally-eclipsing binary (RA=06:40:29.11; Dec=+38:56:52.2; J=2000.0; Rmax=17.2 mag) with an sdO primary and a strongly irradiated red dwarf compani…
Measuring differential rotation of the K-giant \,And
Zs. KÅvári, H. Korhonen, L. Kriskovics +5
We investigate the temporal spot evolution of the K-giant component in the RS CVn-type binary system \,Andromedae to establish its surface differential rotation. Doppler imagin…
Multicolour photometry of the M0V+M5V eclipsing binary V405 And
K. Vida, K. Olah, Zs. Kovari +1
We present multicolour photometry and modelling of the active eclipsing binary star V405 And. The components of 0.2 and 0.5 solar masses are just below and above the theoretical li…
Spots, flares, accretion, and obscuration in the pre-main sequence binary DQ Tau
Ã. Kóspál, P. Ãbrahám, G. Zsidi +4
DQ Tau is a young low-mass spectroscopic binary, consisting of two almost equal-mass stars on a 15.8 day period surrounded by a circumbinary disk. We analyzed DQ Tau's light curves…
Variable star classification with a Multiple-Input Neural Network
T. Szklenár, A. Bódi, D. Tarczay-Nehéz +3
In this experiment, we created a Multiple-Input Neural Network, consisting of Convolutional and Multi-layer Neural Networks. With this setup the selected highest-performing neural…
SN 2021gno: a Calcium-rich transient with double-peaked light curves
K. Ertini, G. Folatelli, L. Martinez +52
We present extensive ultraviolet (UV) and optical photometric and optical spectroscopic follow-up of supernova (SN)~2021gno by the "Precision Observations of Infant Supernova Explo…
Abundant sub-micron grains revealed in newly discovered extreme debris discs
A. Moór, P. Ãbrahám, K. Y. L. Su +7
Extreme debris discs (EDDs) are bright and warm circumstellar dusty structures around main sequence stars. They may represent the outcome of giant collisions occuring in the terres…
The Multi-periodic Blazhko Modulation of CZ Lacertae
Ã. Sódor, J. Jurcsik, B. Szeidl +7
Thorough analysis of the multicolour CCD observations of the RRab-type variable, CZ Lacertae is presented. The observations were carried out in two consecutive observing seasons in…
EI Eridani: a star under the influence -- The effect of magnetic activity in the short and long term
L. Kriskovics, Zs. KÅvári, B. Seli +5
We use our photometric time series of more than forty years to analyze the long-term behaviour of EI Eri. Flare activity is investigated using space-borne photometric data obtained…
A quest for activity cycles in low mass stars
K. Vida, L. Kriskovics, K. Oláh
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…
Searching for stellar CMEs in the Praesepe and Pleiades clusters
K. Vida, B. Seli, R. M. Roettenbacher +4
On the Sun, the energetic, erupting phenomena of flares and coronal mass ejections (CMEs) often occur together. While space-based photometry has revealed frequent white-light flare…
Doppler maps and surface differential rotation of EI Eri from the MUSICOS 1998 observations
Zs. KÅvári, A. Washuettl, B. H. Foing +4
We present time-series Doppler images of the rapidly-rotating active binary star EI Eri from spectroscopic observations collected during the MUSICOS multi-site campaign in 1998, si…
M-Dwarf Fast Rotators and the Detection of Relatively Young Multiple M-Star Systems
S. Rappaport, J. Swift, A. Levine +9
We have searched the Kepler light curves of ~3900 M-star targets for evidence of periodicities that indicate, by means of the effects of starspots, rapid stellar rotation. Several…
Anti-solar differential rotation and surface flow pattern on UZ Librae
K. Vida, Zs. KÅvári, M. Å vanda +4
We re-investigate UZ Librae spectra obtained at KPNO in 1998 and 2000. From the 1998 data we compose 11 consecutive Doppler images using the Ca I-6439, Fe I-6393 and Fe I-6411 line…
A star under multiple influences. Magnetic activity in V815 Her, a compact 2+2 hierarchical system
Zs. Kovari, K. G. Strassmeier, L. Kriskovics +7
We are conducting a comprehensive investigation of V815 Her using photometric and spectroscopic data to understand the origin of the activity and what influences it in the short an…
A multi-epoch, multi-wavelength study of the classical FUor V1515 Cyg approaching quiescence
Zs. M. Szabó, Ã. Kóspál, P. Ãbrahám +28
Historically, FU Orionis-type stars are low-mass, pre-main sequence stars. The members of this class experience powerful accretion outbursts and remain in an enhanced accretion sta…
Towards the true number of flaring giant stars in the Kepler field. Are there flaring specialities associated with the giant nature?
K. Oláh, Zs. KÅvári, M. N. Günther +4
We aim to give a reliable estimate of the number of flaring giant stars in the Kepler field. By analyzing the flaring activity of these stars we explore their flare statistics and…
Antisolar differential rotation with surface lithium enrichment on the single K-giant V1192 Orionis
Zs. KÅvári, K. G. Strassmeier, T. A. Carroll +7
Context: Stars with about 12 solar masses at the red giant branch (RGB) represent an intriguing period of stellar evolution, i.e. when the convective envelope interacts with the…
An extensive photometric study of the Blazhko RR Lyrae star RZ Lyr
J. Jurcsik, Ã. Sódor, G. Hajdu +13
The analysis of recent, extended multicolour CCD and archive photoelectric, photographic and visual observations has revealed several important properties of RZ Lyr, an RRab-type v…
Study of FK Comae Berenices: VII. Correlating photospheric and chromospheric activity
K. Vida, H. Korhonen, I. V. Ilyin +3
We study the connection between the chromospheric and photospheric behaviour of the active late-type star FK Comae. We use spot temperature modelling, light curve inversion based o…
First Results of The Konkoly Blazhko Survey II
Ã. Sódor, J. Jurcsik, L. Molnár +17
The two parts of the Konkoly Blazhko Survey (KBS I and II) are introduced. The most important preliminary findings of the second part are presented in comparison to the results of…
Activity of 50 Long-Period Comets Beyond 5.2 AU
K. Sarneczky, Gy. M. Szabo, B. Csak +10
Remote investigations of the ancient solar system matter has been traditionally carried out through the observations of long-period (LP) comets that are less affected by solar irra…
Overtone and multi-mode RR Lyrae stars in the globular cluster M3
J. Jurcsik, P. Smitola, G. Hajdu +15
The overtone and multi-mode RR Lyrae stars in the globular cluster M3 are studied using a 200-d long, and time-series photometry obtained in 2012. 70\% of the…
A census of Coronal Mass Ejections on solar-like stars
M. Leitzinger, P. Odert, R. Greimel +8
Coronal Mass Ejections (CMEs) may have major importance for planetary and stellar evolution. Stellar CME parameters, such as mass and velocity, have yet not been determined statist…
Photometric and radial-velocity time-series of RR Lyrae stars in M3: analysis of single-mode variables
J. Jurcsik, P. Smitola, G. Hajdu +18
We present the first simultaneous photometric and spectroscopic investigation of a large set of RR Lyrae variables in a globular cluster. The radial-velocity data presented compris…
Eclipsing Spotted Giant Star With K2 and Historical Photometry
K. Oláh, S. Rappaport, T. Borkovits +15
Context. Stars can maintain their observable magnetic activity from the PMS to the tip of the red giant branch. However, the number of known active giants is much lower than active…
Magnetic activity in cool stars: manifestations and relevance to exoplanets
E. IÅık, A. Valio, A. Strugarek +10
Understanding stellar magnetic activity is central to exoplanet science in two ways: it sets the dynamic astrospheric boundary condition governing planetary space environments, and…
Looking for activity cycles in late-type Kepler stars using time-frequency analysis
K. Vida, K. Oláh, R. Szabó
We analyse light curves covering four years of 39 fast-rotating () late-type active stars from the Kepler database. Using time-frequency analysis (Short-Term Fo…
An extensive photometric study of the Blazhko RR Lyrae star MW Lyr: I. Light curve solution
J. Jurcsik, Ã. Sódor, Zs. Hurta +10
We have obtained the most extensive and most accurate photometric data of a Blazhko variable MW Lyr during the 2006-2007 observing seasons. The data within each 0.05 phase bin of t…
Surface magnetic activity of the fast-rotating G5-giant IN Comae, central star of the faint planetary nebula LoTr 5
Zs. KÅvári, K. G. Strassmeier, K. Oláh +8
On the AGB, low to intermediate mass stars blow away their outer envelopes, forming planetary nebulae. Interaction between the planetary nebula and its central progenitor is poorly…
Magnitude-range brightness variations of overactive K giants
K. Oláh, A. Moór, Zs. KÅvári +4
We study three representative, overactive spotted K giants (IL Hya, XX Tri, and DM UMa) known to exhibit V-band light variations between 0.65-1.05 mags. Our aim is to find the orig…