@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}
}

@article{MTMT:33538419,
	title = {Characteristics of flares on giant stars},
	url = {https://m2.mtmt.hu/api/publication/33538419},
	author = {Oláh, Katalin Ilona and Seli, Bálint Attila and Kővári, Zsolt and Kriskovics, Levente and Vida, Krisztián},
	doi = {10.1051/0004-6361/202243789},
	journal-iso = {ASTRON ASTROPHYS},
	journal = {ASTRONOMY & ASTROPHYSICS},
	volume = {668},
	unique-id = {33538419},
	issn = {0004-6361},
	abstract = {Context. Although late-type dwarfs and giant stars are substantially different, their flares are thought to originate in similar physical processes and differ only by a scale factor in the energy levels. We study the validity of this approach.},
	year = {2022},
	eissn = {1432-0746},
	orcid-numbers = {Seli, Bálint Attila/0000-0002-3658-2175; Kővári, Zsolt/0000-0001-5160-307X}
}

@article{MTMT:33537935,
	title = {Photometric and Spectroscopic Study of the EXor-like Eruptive Young Star Gaia19fct},
	url = {https://m2.mtmt.hu/api/publication/33537935},
	author = {Park, Sunkyung and Kóspál, Ágnes and Ábrahám, Péter and Fernando, Cruz-Saenz de Miera and Fiorellino, Elenonora and Siwak, Michal and Nagy, Zsófia and Giannini, Teresa and Carini, Roberta and Szabó, Zsófia Marianna and Lee, Jeong-Eun and Lee, Jae-Joon and Vitali, Fabrizio and Kun, Mária and Cseh, Borbála and Krezinger, Máté and Kriskovics, Levente and Ordasi, András and Pál, András and Szakáts, Róbert and Vida, Krisztián and Vinkó, József},
	doi = {10.3847/1538-4357/aca01e},
	journal-iso = {ASTROPHYS J},
	journal = {ASTROPHYSICAL JOURNAL},
	volume = {941},
	unique-id = {33537935},
	issn = {1538-4357},
	abstract = {Gaia19fct is one of the Gaia-alerted eruptive young stars that has undergone several brightening events. We conducted monitoring observations using multifilter optical and near-infrared photometry, as well as near-infrared spectroscopy, to understand the physical properties of Gaia19fct and investigate whether it fits into the historically defined two classes. We present the analyses of light curves, color variations, spectral lines, and CO modeling. The light curves show at least five brightening events since 2015, and the multifilter color evolutions are mostly gray. The gray evolution indicates that bursts are triggered by mechanisms other than extinction. Our near-infrared spectra exhibit both absorption and emission lines and show time variability throughout our observations. We found lower rotational velocity and lower temperature from the near-infrared atomic absorption lines than from the optical lines, suggesting that Gaia19fct has a Keplerian rotating disk. The CO overtone features show a superposition of absorption and emission components, which is unlike other young stellar objects. We modeled the CO lines, and the result suggests that the emission and absorption components are formed in different regions. We found that although Gaia19fct exhibits characteristics of both types of eruptive young stars, FU Orionis–type objects and EX Lupi–type objects, it shows more similarity with EXors in general.},
	year = {2022},
	eissn = {0004-637X},
	orcid-numbers = {Giannini, Teresa/0000-0002-7035-8513; Carini, Roberta/0000-0003-1604-2064; Szabó, Zsófia Marianna/0000-0001-9830-3509; Lee, Jeong-Eun/0000-0003-3119-2087; Lee, Jae-Joon/0000-0003-0894-7824; Vitali, Fabrizio/0000-0001-8332-4227; Vinkó, József/0000-0001-8764-7832}
}

@article{MTMT:33535919,
	title = {Erratum: “A New Sample of Warm Extreme Debris Disks from the ALLWISE Catalog” (2021, ApJ, 910, 27)},
	url = {https://m2.mtmt.hu/api/publication/33535919},
	author = {Moór, Attila and Ábrahám, Péter and Szabó M., Gyula and Vida, Krisztián and Cataldi, Gianni and Derekas, Alíz and Henning, Thomas and Kinemuchi, Karen and Kóspál, Ágnes and Kovács, József and Pál, András and Sarkis, Paula and Seli, Bálint Attila and Szabó, Zsófia M. and Takáts, Katalin},
	doi = {10.3847/1538-4357/aca280},
	journal-iso = {ASTROPHYS J},
	journal = {ASTROPHYSICAL JOURNAL},
	volume = {940},
	unique-id = {33535919},
	issn = {1538-4357},
	year = {2022},
	eissn = {0004-637X},
	orcid-numbers = {Szabó M., Gyula/0000-0002-0606-7930; Cataldi, Gianni/0000-0002-2700-9676; Derekas, Alíz/0000-0002-6526-9444; Henning, Thomas/0000-0002-1493-300X; Kinemuchi, Karen/0000-0001-7908-7724; Sarkis, Paula/0000-0001-8128-3126; Seli, Bálint Attila/0000-0002-3658-2175; Szabó, Zsófia M./0000-0001-9830-3509}
}