@misc{MTMT:35207603,
	title = {NEOWISE-R Caught the Luminous SN 2023ixf in Messier 101},
	url = {https://m2.mtmt.hu/api/publication/35207603},
	author = {Van, Dyk Schuyler D. and Szalai, Tamas and Cutri, Roc M. and Kirkpatrick, J. Davy and Grillmair, Carl J. and Fajardo-Acosta, Sergio B. and Masiero, Joseph R. and Mainzer, Amy K. and Gelino, Christopher R. and Vinkó, József and Joo, Andras Peter and Pál, András and Könyves-Tóth, Réka and Kriskovics, Levente and Szakáts, Róbert and Vida, Krisztián and Zheng, WeiKang and Brink, Thomas G. and Filippenko, Alexei V.},
	doi = {10.48550/arXiv.2406.18005},
	unique-id = {35207603},
	abstract = {The reactivated Near-Earth Object Wide-field Infrared Survey Explorer (NEOWISE-R) serendipitously caught the Type II supernova SN 2023ixf in Messier 101 on the rise, starting day 3.6 through day 10.9, and on the late-time decline from days 211 through 213 and days 370 through 372. We have considered these mid-infrared (mid-IR) data together with observations from the ultraviolet (UV) through the near-IR, when possible. At day 3.6 we approximated the optical emission with a hot, ~26,630 K blackbody, with a notable UV excess likely from strong SN shock interaction with circumstellar matter (CSM). In the IR, however, a clear excess is also obvious, and we fit it with a cooler, ~1,620 K blackbody with radius of ~2.6 x 10^{15} cm, consistent with dust in the progenitor's circumstellar shell likely heated by the UV emission from the CSM interaction. On day 10.8, the light detected was consistent with SN ejecta-dominated emission. At late times we also observed a clear NEOWISE-R excess, which could arise either from newly formed dust in the inner ejecta or in the contact discontinuity between the forward and reverse shocks, or from more distant pre-existing dust grains in the SN environment. Furthermore, the large 4.6 micron excess at late times can also be explained by the emergence of the carbon monoxide 1--0 vibrational band. SN 2023ixf is the best-observed SN IIP in the mid-IR during the first several days after explosion and one of the most luminous such SNe ever seen.},
	keywords = {Astrophysics - Solar and Stellar Astrophysics; Astrophysics - High Energy Astrophysical Phenomena; Astrophysics - Astrophysics of Galaxies},
	year = {2024},
	orcid-numbers = {Vinkó, József/0000-0001-8764-7832}
}

@article{MTMT:34970101,
	title = {The enigma of Gaia18cjb: A possible rare hybrid of FUor and EXor properties},
	url = {https://m2.mtmt.hu/api/publication/34970101},
	author = {Fiorellino, Elenonora and Ábrahám, Péter and Kóspál, Ágnes and Kun, Mária and Alcalá, Juan M. and Caratti, o Garatti Alessio and Fernando, Cruz-Saenz de Miera and García-Álvarez, David and Giannini, Teresa and Park, Sunkyung and Siwak, Michal and Szilágyi, Máté and Covino, Elvira and Marton, Gábor and Nagy, Zsófia and Nisini, Brunella and Marianna, Szabó Zsófia and Bora, Zsófia and Cseh, Borbála and Kalup, Csilla and Krezinger, Máté and Kriskovics, Levente and Ogłoza, Waldemar and Pál, András and Sódor, Ádám and Sonbas, Eda and Szakáts, Róbert and Vida, Krisztián and Vinkó, József and Wyrzykowski, Lukasz and Zielinski, Pawel},
	doi = {10.1051/0004-6361/202347777},
	journal-iso = {ASTRON ASTROPHYS},
	journal = {ASTRONOMY & ASTROPHYSICS},
	volume = {686},
	unique-id = {34970101},
	issn = {0004-6361},
	abstract = {Context. Gaia18cjb is one of the Gaia-alerted eruptive young star candidates that has been experiencing a slow and strong brightening during the last 13 years, similarly to some FU Orionis-type objects. Aims: The aim of this work is to derive the young stellar nature of Gaia18cjb and determine its physical and accretion properties to classify its variability. Methods: We conducted monitoring observations using multi-filter optical and near-infrared (NIR) photometry, as well as NIR spectroscopy. We present an analysis of pre-outburst and outburst optical and IR light curves, color-magnitude diagrams in different bands, the detection of NIR spectral lines, and estimates of both stellar and accretion parameters during the burst. Results: The optical light curve shows an unusually long (over 8 years) brightening event of 5 mag in the last 13 years, before reaching a plateau indicating that the burst is still ongoing, suggesting a FU Orionis-like (FUor-like) nature. The same outburst is less strong in the IR light curves. The NIR spectra, obtained during the outburst, exhibit emission lines typical of highly accreting low-intermediate mass young stars with typical EX Lupi-type (EXor) features. The spectral index of Gaia18cjb SED classifies it as a Class I in the pre-burst stage and a flat-spectrum young stellar object (YSO) during the burst. Conclusions: Gaia18cjb is an eruptive YSO that exhibits FUor-like photometric features (in terms of brightening amplitude and length of the burst) as well as EXor-like spectroscopic features and accretion rate. Its nature appears similar to that of V350 Cep and V1647 Ori, which have been classified as objects in between FUors and EXors. Spectra from various sources (LT, LBT, GTC) are available at the CDS via anonymous ftp to cdsarc.cds.unistra.fr (ftp://130.79.128.5) or via https://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/686/A160 Based on observations collected at the Large Binocular Telescope under LBT programme IT-2019B-008, the European Southern Observatory under ESO/NTT programmes 105.203T.001 and 105.203T.003, and the Gran Telescopio Canarias under GTC program GTC29-22B.},
	keywords = {ACCRETION; stars: formation; stars: pre-main sequence; stars: low-mass; ACCRETION DISKS; stars: protostars; Techniques: imaging spectroscopy},
	year = {2024},
	eissn = {1432-0746},
	orcid-numbers = {Szilágyi, Máté/0000-0002-3648-433X; Vinkó, József/0000-0001-8764-7832}
}

@article{MTMT:34862224,
	title = {A star under multiple influences. Magnetic activity in V815 Her, a compact 2+2 hierarchical system},
	url = {https://m2.mtmt.hu/api/publication/34862224},
	author = {Kővári, Zsolt and Strassmeier, K. G. and Kriskovics, Levente and Oláh, Katalin Ilona and Borkovits, Tamás and Radványi, Ádám and Granzer, T. and Seli, Bálint Attila and Vida, Krisztián and Weber, M.},
	doi = {10.1051/0004-6361/202348324},
	journal-iso = {ASTRON ASTROPHYS},
	journal = {ASTRONOMY & ASTROPHYSICS},
	volume = {684},
	unique-id = {34862224},
	issn = {0004-6361},
	abstract = {Context. Close binaries with magnetically active components are astrophysical laboratories for studying the effects of binarity on activity. Of particular interest are binary and multiple star systems that contain a solar-type active component with an internal structure similar to the Sun, allowing us to study how the dynamo of a solar-type star would work under different conditions.},
	year = {2024},
	eissn = {1432-0746},
	orcid-numbers = {Kővári, Zsolt/0000-0001-5160-307X; Strassmeier, K. G./0000-0002-6192-6494; Borkovits, Tamás/0000-0002-8806-496X; Radványi, Ádám/0000-0001-5848-2960; Granzer, T./0000-0002-5310-1521; Seli, Bálint Attila/0000-0002-3658-2175; Weber, M./0000-0002-7032-2967}
}

@article{MTMT:34566634,
	title = {Abundant sub-micron grains revealed in newly discovered extreme debris discs},
	url = {https://m2.mtmt.hu/api/publication/34566634},
	author = {Moór, Attila and Ábrahám, Péter and Su, K Y L and Henning, T and Marino, S and Chen, Lei and Kóspál, Ágnes and Pawellek, Nicole and Varga, József and Vida, Krisztián},
	doi = {10.1093/mnras/stae155},
	journal-iso = {MON NOT R ASTRON SOC},
	journal = {MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY},
	volume = {528},
	unique-id = {34566634},
	issn = {0035-8711},
	abstract = {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 terrestrial region between large planetesimals or planetary bodies, and thus provide a rare opportunity to peer into the aftermaths of these events. Here, we report on results of a mini-survey we conducted with the aim to increase the number of known EDDs, investigate the presence of solid-state features around 10 μm in eight EDDs, and classify them into the silica or silicate dominated groups. We identify four new EDDs and derive their fundamental properties. For these, and for four other previously known discs, we study the spectral energy distribution around 10 μm by means of VLT/VISIR photometryin three narrow-band filters and conclude that all eight objects likely exhibit solid-state emission features from sub-micron grains. We find that four discs probably belong to the silicate dominated subgroup. Considering the age distribution of the entire EDD sample, we find that their incidence begins to decrease only after 300 Myr, suggesting that the earlier common picture that these objects are related to the formation of rocky planets may not be exclusive, and that other processes may be involved for older objects (≳100 Myr). Because most of the older EDD systems have wide, eccentric companions, we suggest that binarity may play a role in triggering late giant collisions.},
	year = {2024},
	eissn = {1365-2966},
	pages = {4528-4546},
	orcid-numbers = {Marino, S/0000-0002-5352-2924}
}

@CONFERENCE{MTMT:34718724,
	title = {Stellar flares with PLATO},
	url = {https://m2.mtmt.hu/api/publication/34718724},
	author = {Raetz, Stefanie and Stelzer, Beate and Vicanek, Martinez Tobias and Bruno, Giovanni and Vida, Krisztián and Feliz, Dax and Stassun, Keivan},
	booktitle = {PLATO Stellar Science Conference 2023},
	doi = {10.5281/zenodo.8143624},
	unique-id = {34718724},
	abstract = {Stellar flares are powerful localized eruptions caused by magnetic reconnection events in a star's magnetosphere that can be seen across the entire electromagnetic spectrum. Over short timescales of minutes to a few hours, they emit energies up to 10^38 erg. Flares are important diagnostics for our understanding of coronal physics as well as the evolution of planetary atmospheres. While flares with energies >10^34 erg can lead to an erosion of the ozone layer of the planet's atmosphere when they occur frequently enough, a minimum flare frequency and energy might be required to trigger chemical reactions that are necessary for the development of life. The PLATO mission with its unprecedented precision, short cadence and long observational baseline, is ideally suited to study stellar white-light flares in up to now unrivaled detail. Flares will be identified within the PLATO pipeline MSAP1 with a code developed by the PLATO WP 123 700 ("Stellar flares") both in order to remove stellar variability from the light curves and to extract astrophysically important information. The first prototype of the code was already delivered to the PDC. In this talk I provide a brief summary of the work carried out in the PLATO WP and I will show examples of applications of the flare detection algorithm we develop for MSAP1 to selected stellar samples, e.g. the TESS HZCat M dwarf sample or the Kepler Superflare sample. Furthermore, I will show how the derived flare properties help to estimate the effects of flaring on the habitability of exoplanets.},
	keywords = {Zenodo community pssc23},
	year = {2023}
}

@inproceedings{MTMT:34683543,
	title = {Finding Stellar Flares with Recurrent Deep Neural Networks},
	url = {https://m2.mtmt.hu/api/publication/34683543},
	author = {Bódi, Attila and Vida, Krisztián},
	booktitle = {1st International Conference on Machine Learning for Astrophysics, ML4ASTRO 2022},
	doi = {10.1007/978-3-031-34167-0_21},
	volume = {60},
	unique-id = {34683543},
	year = {2023},
	pages = {105-109},
	orcid-numbers = {Bódi, Attila/0000-0002-8585-4544}
}

@article{MTMT:34232492,
	title = {SN 2021gno: a calcium-rich transient with double-peaked light curves},
	url = {https://m2.mtmt.hu/api/publication/34232492},
	author = {Ertini, K. and Folatelli, G. and Martinez, L. and Bersten, M. C. and Anderson, J. P. and Ashall, C. and Baron, E. and Bose, S. and Brown, P. J. and Burns, C. and DerKacy, J. M. and Ferrari, L. and Galbany, L. and Hsiao, E. and Kumar, S. and Lu, J. and Mazzali, P. and Morrell, N. and Orellana, M. and Pessi, P. J. and Phillips, M. M. and Piro, A. L. and Polin, A. and Shahbandeh, M. and Shappee, B. J. and Stritzinger, M. and Suntzeff, N. B. and Tucker, M. and Elias-Rosa, N. and Kuncarayakti, H. and Gutiérrez, C. P. and Kozyreva, A. and Müller-Bravo, T. E. and Chen, T. -W. and Hinkle, J. T. and Payne, A. V. and Székely, Péter and Szalai, Tamás and Barna, Barnabás and Könyves-Tóth, Réka and Bánhidi, D. and Bíró, I. B. and Csányi, István and Kriskovics, Levente and Pál, András and Szabó, Zs and Szakáts, Róbert and Vida, Krisztián and Vinkó, József and Gromadzki, M. and Harvey, L. and Nicholl, M. and Paraskeva, E. and Young, D. R. and Englert, B.},
	doi = {10.1093/mnras/stad2705},
	journal-iso = {MON NOT R ASTRON SOC},
	journal = {MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY},
	volume = {526},
	unique-id = {34232492},
	issn = {0035-8711},
	abstract = {We present extensive ultraviolet (UV) and optical photometric and optical spectroscopic follow-up of supernova (SN) 2021gno by the 'Precision Observations of Infant Supernova Explosions' (POISE) project, starting less than 2 d after the explosion. Given its intermediate luminosity, fast photometric evolution, and quick transition to the nebular phase with spectra dominated by [Ca II] lines, SN 2021gno belongs to the small family of Calcium-rich transients. Moreover, it shows double-peaked light curves, a phenomenon shared with only four other Calcium-rich events. The projected distance from the centre of the host galaxy is not as large as other objects in this family. The initial optical light-curve peaks coincide with a very quick decline of the UV flux, indicating a fast initial cooling phase. Through hydrodynamical modelling of the bolometric light curve and line velocity evolution, we found that the observations are compatible with the explosion of a highly stripped massive star with an ejecta mass of $0.8\\, M_\\odot$ and a 56Ni mass of 0.024 M⊙. The initial cooling phase (first light-curve peak) is explained by the presence of an extended circumstellar material comprising ~$10^{-2}\\, {\\rm M}_{\\odot }$ with an extension of $1100\\, R_{\\odot }$. We discuss if hydrogen features are present in both maximum-light and nebular spectra, and their implications in terms of the proposed progenitor scenarios for Calcium-rich transients.},
	keywords = {Astrophysics - Solar and Stellar Astrophysics; supernovae: general; Astrophysics - High Energy Astrophysical Phenomena; stars: massive; supernovae: individual: SN 2021gno},
	year = {2023},
	eissn = {1365-2966},
	pages = {279-298},
	orcid-numbers = {Vinkó, József/0000-0001-8764-7832}
}

@article{MTMT:34221293,
	title = {Three is the magic number: Distance measurement of NGC 3147 using SN 2021hpr and its siblings},
	url = {https://m2.mtmt.hu/api/publication/34221293},
	author = {Barna, Barnabás and Nagy, Andrea and Bora, Zs. and Czavalinga, Donát Róbert and Könyves-Tóth, Réka and Szalai, Tamás and Székely, Péter and Zsíros, Szanna and Banhidi, D. and Biro, I. B. and Csanyi, I. and Kriskovics, Levente and Pál, András and Szabo, Zs. M. and Szakáts, Róbert and Vida, Krisztián and Bodola, Zsófia Réka and Vinkó, József},
	doi = {10.1051/0004-6361/202346395},
	journal-iso = {ASTRON ASTROPHYS},
	journal = {ASTRONOMY & ASTROPHYSICS},
	volume = {677},
	unique-id = {34221293},
	issn = {0004-6361},
	abstract = {Context. The nearby spiral galaxy NGC 3147 hosted three Type Ia supernovae (SNe Ia) in the past decades that have been the subjects of intense follow-up observations. Simultaneous analysis of their data provides a unique opportunity for testing different methods of light curve fitting and distance estimation.Aims. The detailed optical follow-up of SN 2021hpr allows us to revise the previous distance estimations to NGC 3147 and compare the widely used light curve fitting algorithms to each other. After the combination of the available and newly published data of SN 2021hpr, its physical properties can also be estimated with higher accuracy.Methods. We present and analyse new BVgriz and Swift photometry of SN 2021hpr to constrain its general physical properties. Together with its siblings, SNe 1997bq and 2008fv, we cross-compared the individual distance estimates of these three SNe given by the Spectral Adaptive Lightcurve Template (SALT) code, and we also checked their consistency with the results from the Multi-Color Light Curve Shape (MLCS) code. The early spectral series of SN 2021hpr was also fit with the radiative spectral code TARDIS to verify the explosion properties and constrain the chemical distribution of the outer ejecta.Results. After combining the distance estimates for the three SNe, the mean distance to their host galaxy, NGC 3127, is 42.5 +/- 1.0 Mpc, which matches with the distance inferred by the most up-to-date light curve fitters, SALT3 and BayeSN. We confirm that SN 2021hpr is a Branch-normal Type Ia SN that ejected -1.12 +/- 0.28 M-circle dot from its progenitor white dwarf and synthesized -0.44 +/- 0.14 M-circle dot of radioactive Ni-56.},
	keywords = {radiative transfer; supernovae: general; Galaxies: distances and redshifts; supernovae: individual: SN 2021hpr},
	year = {2023},
	eissn = {1432-0746},
	orcid-numbers = {Vinkó, József/0000-0001-8764-7832}
}

@article{MTMT:34053151,
	title = {EI Eridani: A star under the influence. The effect of magnetic activity in the short and long term},
	url = {https://m2.mtmt.hu/api/publication/34053151},
	author = {Kriskovics, Levente and Kővári, Zsolt and Seli, Bálint Attila and Oláh, Katalin Ilona and Vida, Krisztián and Henry, G. W. and Granzer, T. and Görgei, A.},
	doi = {10.1051/0004-6361/202245767},
	journal-iso = {ASTRON ASTROPHYS},
	journal = {ASTRONOMY & ASTROPHYSICS},
	volume = {674},
	unique-id = {34053151},
	issn = {0004-6361},
	abstract = {Context. Homogeneous photometric time series spanning decades provide a unique opportunity to study the long-term cyclic behavior of active spotted stars such as our target EI Eridani. In addition, with ultraprecise space photometry data, it is possible to investigate the accompanying flare activity in detail. However, the rotation period of ≈2 days for EI Eri makes it impossible to achieve time-resolved surface images from a single ground-based observing site. Therefore, for this purpose, spectroscopic data from a multi-site observing campaign are needed.},
	year = {2023},
	eissn = {1432-0746},
	orcid-numbers = {Kővári, Zsolt/0000-0001-5160-307X; Seli, Bálint Attila/0000-0002-3658-2175; Görgei, A./0009-0002-1289-7946}
}

@misc{MTMT:33729197,
	title = {VizieR Online Data Catalog: Opt-to-IR monitoring obs. of V1057 Cyg (Szabo+, 2021)},
	url = {https://m2.mtmt.hu/api/publication/33729197},
	author = {Szabo, Z. M. and Kóspál, Ágnes and Ábrahám, Péter and Park, Sunkyung and Siwak, Michal and Green, J. D. and Moór, Attila and Pál, András and Acosta-Pulido, J. A. and Lee, J. -E. and Cseh, B. and Csornyei, G. and Hanyecz, O. and Könyves-Tóth, Réka and Krezinger, M. and Kriskovics, Levente and Ordasi, A. and Sárneczky, Krisztián and Seli, B. and Szakáts, Róbert and Szing, A. and Vida, Krisztián},
	unique-id = {33729197},
	abstract = {We performed the majority of our photometric observations in B, V, RC, IC , g', r', and i' filters at the Piszkesteto Mountain Station of Konkoly Observatory (Hungary) between 2005 and 2021. Three telescopes with three slightly different optical systems were used: the 1m Ritchey-Chretien-coude (RCC) telescope, the 60/90/180cm Schmidt telescope and the Astro Systeme Austria AZ800 alt-azimuth direct drive 80cm Ritchey-Chretien (RC80) telescope; see Section 2.1. In addition to our national facilities, we occasionally used other telescopes. On 2006 July 20 and 2012 October 13 we obtained B, V, RJ, and IJ images of V1057 Cyg with the IAC80 telescope of the Instituto de Astrofisica de Canarias located at Teide Observatory (Canary Islands, Spain). During 2019 August-September, in parallel with TESS, we additionally observed V1057 Cyg at the Northern Skies Observatory (NSO). We used the 0.4m telescope equipped with BVI filters. We also observed V1057 Cyg with the 2.56m Nordic Optical Telescope (NOT) at the Roque de los Muchachos Observatory, La Palma, in the Canary Islands (Plan ID 61-414, PI: Zs. M. Szabo). For optical imaging we used the Alhambra Faint Object Spectrograph and Camera (ALFOSC) on 2020 August 17. The Bessel BVR filter set was supplemented by an i interference filter, which is similar to the SLOAN i', but with a slightly longer effective wavelength of λeff=0.789um. We obtained NIR images in the J, H, and Ks bands at six epochs between 2006 July 15 and 2012 October 13 using the 1.52m Telescopio Carlos Sanchez (TCS) at the Teide Observatory. We also used the NOTCam instrument on the NOT on 2020 August 29. See Section 2.3. We obtained a new optical spectrum of V1057 Cyg with the high-resolution FIbre-fed Echelle Spectrograph (FIES) instrument on the NOT on 2020 August 17. We used a fiber with a larger entrance aperture of 2.5", which provided a spectral resolution R=25000, covering the 370-900nm wavelength range. V1057 Cyg was also observed with the Bohyunsan Optical Echelle Spectrograph (BOES) installed on the 1.8m telescope at the Bohyunsan Optical Astronomy Observatory (BOAO). It provides R=30000 in the wavelength range ~400-900nm. The first spectrum was obtained on 2012-September-11 and the last on 2018-December-18. See Section 2.4. On 2020 August 29, we used the NOTCam on the NOT to obtain new NIR spectra of V1057 Cyg and Iot Cyg (A5 V) as our telluric standard star in the JHKs bands. We used the low-resolution camera mode (R=2500). See Section 2.5. On 2018 September 6, we observed V1057 Cyg with the Stratospheric Observatory for Infrared Astronomy (SOFIA) using the Faint Object infraRed CAmera for the SOFIA Telescope (FORCAST). We obtained mid-infrared imaging in a series of short exposures in band F111 (10.6-11.6um) totaling ~30s, a single exposure in F056 (5.6um) for 37s and F077 (7.5-8um) for 42s, and R~100-200 spectra with G063 (5-8um) and G227 (17-27um) (Plan ID 06_062, PI: J. D. Green). See Section 2.6. (2 data files).},
	keywords = {stars: pre-main sequence; Photometry: UBVRI; Spectra: infrared},
	year = {2023}
}