Explanipedia

BHTOM and the European Astronomical Society of Small Telescopes (EASST): Bridging Professional and Amateur Astronomers in Microlensing Studies Open

M. Maskoliūnas, Ł. Wyrzykowski, E. Stonkutė, Paweł Zieliński, J. Zdanavičius , et al. · 2025

The Black Hole Target and Observation Manager (BHTOM.SPACE) is a powerful yet accessible web-based platform that enables both amateur and professional astronomers to contribute to cutting-edge astrophysical research. Developed within the E…

BHTOM: The Power of Many Open

A. Fraser Gillan, Ł. Wyrzykowski · 2025

Time-domain astronomy, driven by the current wide-field surveys such as ATLAS (Tonry et al., 2018), Pan-STARRS (Chambers et al., 2016) and ZTF (Bellm et al., 2019) has become essential for studying rapidly evolving astrophysical phenomena.…

The 2023 Outburst of the Gaia Alerted EXor Gaia23bab Open

Z. Nagy, Á. Kóspál, P. Ábrahám, T. Giannini, M. Kun , et al. · 2025

Episodic accretion is a fundamental process in the build-up of the stellar mass. EX Lupi-type eruptive young stars (EXors) represent one of the main types of episodic accretion. We study the recently discovered EXor Gaia23bab during its 20…

Is the symbiotic recurrent nova T CrB late? Recent photometric evolution and comparison with past pre-outburst behaviour Open

Jaroslav Merc, Ł. Wyrzykowski, P. G. Beck, P. Mikołajczyk, Krzysztof Kotysz , et al. · 2025

T CrB is a symbiotic recurrent nova that last erupted in 1946. Given its recurrence time-scale of approximately 80 yr, the next outburst is eagerly anticipated by the astronomical community. In this work, we analyse the optical light curve…

The 2023 outburst of the Gaia alerted EXor Gaia23bab Open

Z. Nagy, Á. Kóspál, P. Ábrahám, T. Giannini, M. Kun , et al. · 2025

Episodic accretion is a fundamental process in the build-up of the stellar mass. EX Lupi-type eruptive young stars (EXors) represent one of the main types of episodic accretion. We study the recently discovered EXor Gaia23bab during its 20…

AT2021uey: A planetary microlensing event outside the Galactic bulge Open

Makiko Ban, P Voloshyn, R. Adomavičienė, E. Bachelet, V. Bozza , et al. · 2025

We report the analysis of a planetary microlensing event AT2021uey. The event was observed outside the Galactic bulge and alerted both space-( Gaia ) and ground-based (ZTF and ASAS-SN) surveys. From the observed data, we find that the lens…

Gaia20bdk – New FU Ori-type star in the Sh 2-301 star-forming region Open

M. Siwak, Á. Kóspál, P. Ábrahám, G. Marton, Paweł Zieliński , et al. · 2025

Context. We analyse multi-colour photometric and spectroscopic observations of the young stellar object (YSO) Gaia20bdk. Aims. We aim to investigate the exact nature of the eruptive phenomenon that the star has been undergoing since 2018. …

Uncovering the invisible: A study of Gaia18ajz, a candidate black hole revealed by microlensing Open

K. Howil, Ł. Wyrzykowski, K. Kruszyńska, Paweł Zieliński, E. Bachelet , et al. · 2024

Context. Identifying black holes is essential for our understanding of the development of stars and can reveal novel principles of physics. Gravitational microlensing provides an exceptional opportunity to examine an undetectable populatio…

CSS 161010: A Luminous Fast Blue Optical Transient with Broad Blueshifted Hydrogen Lines Open

C. P. Gutiérrez, S. Mattila, Peter Lundqvist, Luc Dessart, S. González–Gaitán , et al. · 2024

We present ultraviolet, optical, and near-infrared photometric and optical spectroscopic observations of the luminous fast blue optical transient (LFBOT) CSS 161010:045834–081803 (CSS 161010). The transient was found in a low-redshift ( z …

Analysis of the Full Spitzer Microlensing Sample. I. Dark Remnant Candidates and Gaia Predictions Open

Krzysztof A. Rybicki, Yossi Shvartzvald, Jennifer C. Yee, S. Calchi Novati, E. O. Ofek , et al. · 2024

In the pursuit of understanding the population of stellar remnants within the Milky Way, we analyze the sample of ∼950 microlensing events observed by the Spitzer Space Telescope between 2014 and 2019. In this study we focus on a subsample…

Analysis of the full Spitzer microlensing sample I: Dark remnant candidates and Gaia predictions Open

Krzysztof A. Rybicki, Yossi Shvartzvald, Jennifer C. Yee, S. Calchi Novati, E. O. Ofek , et al. · 2024

In the pursuit of understanding the population of stellar remnants within the Milky Way, we analyze the sample of $\sim 950$ microlensing events observed by the Spitzer Space Telescope between 2014 and 2019. In this study we focus on a sub…

Gaia22dkvLb: A Microlensing Planet Potentially Accessible to Radial-velocity Characterization Open

Zexuan Wu, Subo Dong, Tuan Yi, Zhuokai Liu, Kareem El-Badry , et al. · 2024

We report discovering an exoplanet from following up a microlensing event alerted by Gaia. The event Gaia22dkv is toward a disk source rather than the traditional bulge microlensing fields. Our primary analysis yields a Jovian planet with …

No massive black holes in the Milky Way halo Open

P. Mróz, A. Udalski, M. K. Szymański, I. Soszyński, Ł. Wyrzykowski , et al. · 2024

Microlensing Optical Depth and Event Rate toward the Large Magellanic Cloud Based on 20 yr of OGLE Observations Open

P. Mróz, A. Udalski, M. K. Szymański, M. Kapusta, I. Soszyński , et al. · 2024

Measurements of the microlensing optical depth and event rate toward the Large Magellanic Cloud (LMC) can be used to probe the distribution and mass function of compact objects in the direction toward that galaxy—in the Milky Way disk, the…

Four microlensing giant planets detected through signals produced by minor-image perturbations Open

Cheongho Han, I. A. Bond, Chung‐Uk Lee, Andrew Gould, Michael D. Albrow , et al. · 2024

Aims. We investigated the nature of the anomalies appearing in four microlensing events KMT-2020-BLG-0757, KMT-2022-BLG-0732, KMT-2022-BLG-1787, and KMT-2022-BLG-1852. The light curves of these events commonly exhibit initial bumps followe…

Four microlensing giant planets detected through signals produced by minor-image perturbations Open

Cheongho Han, I. A. Bond, Chung‐Uk Lee, Andrew Gould, Michael D. Albrow , et al. · 2024

We investigated the nature of the anomalies appearing in four microlensing events KMT-2020-BLG-0757, KMT-2022-BLG-0732, KMT-2022-BLG-1787, and KMT-2022-BLG-1852. The light curves of these events commonly exhibit initial bumps followed by s…

A Close Binary Lens Revealed by the Microlensing Event Gaia20bof Open

E. Bachelet, P. Rota, V. Bozza, Paweł Zieliński, Y. Tsapras , et al. · 2024

During the last 25 yr, hundreds of binary stars and planets have been discovered toward the Galactic bulge by microlensing surveys. Thanks to a new generation of large-sky surveys, it is now possible to regularly detect microlensing events…

The 33 M⊙ black hole Gaia BH3 is part of the disrupted ED-2 star cluster Open

E. Balbinot, Emma Dodd, Tadafumi Matsuno, C. Lardo, A. Helmi , et al. · 2024

Context. The Gaia Collaboration has recently reported the detection of a 33 M ⊙ black hole in a wide binary system located in the solar neighbourhood. Aims. Here we explore the relationship between this black hole, known as Gaia BH3, and t…

A close binary lens revealed by the microlensing event Gaia20bof Open

E. Bachelet, P. Rota, V. Bozza, P. Zielinski, Y. Tsapras , et al. · 2024

During the last 25 years, hundreds of binary stars and planets have been discovered towards the Galactic Bulge by microlensing surveys. Thanks to a new generation of large-sky surveys, it is now possible to regularly detect microlensing ev…

Time-varying double-peaked emission lines following the sudden ignition of the dormant galactic nucleus AT2017bcc Open

E. J. Ridley, M. Nicholl, C. A. Ward, P. K. Blanchard, R. Chornock , et al. · 2024

We present a pan-chromatic study of AT2017bcc, a nuclear transient that was discovered in 2017 within the skymap of a reported burst-like gravitational-wave candidate, G274296. It was initially classified as a superluminous supernova, and …

Gaia21blx: Complete resolution of a binary microlensing event in the Galactic disk Open

P. Rota, V. Bozza, M. Hundertmark, E. Bachelet, R. A. Street , et al. · 2024

Context . Gravitational microlensing is a method that is used to discover planet-hosting systems at distances of several kiloparsec in the Galactic disk and bulge. We present the analysis of a microlensing event reported by the Gaia photom…

Discovery of a dormant 33 solar-mass black hole in pre-release Gaia astrometry Open

P. Panuzzo, T. Mazeh, F. Arenou, B. Holl, E. Caffau , et al. · 2024

Context. Gravitational waves from black-hole (BH) merging events have revealed a population of extra-galactic BHs residing in short-period binaries with masses that are higher than expected based on most stellar evolution models – and also…

The enigma of Gaia18cjb: A possible rare hybrid of FUor and EXor properties Open

Eleonora Fiorellino, P. Ábrahám, Á. Kóspál, M. Kun, J. M. Alcalá , et al. · 2024

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 de…

Uncovering the Invisible: A Study of Gaia18ajz, a Candidate Black Hole Revealed by Microlensing Open

K. Howil, Ł. Wyrzykowski, K. Kruszyńska, Paweł Zieliński, E. Bechelet , et al. · 2024

Identifying black holes is essential for comprehending the development of stars and uncovering novel principles of physics. Gravitational microlensing provides an exceptional opportunity to examine an undetectable population of black holes…

A luminous, fast blue optical transient from a stellar tidaldisruption event by an intermediate-mass black hole Open

C. P. Gutiérrez, S. Mattila, Peter Lundqvist, Luc Dessart, S. González–Gaitán , et al. · 2024

Intermediate-mass black holes (BHs) bridging the gap between stellar mass (M_BH ≤ 100 M⊙) and supermassive BHs (M_BH ≥ 10⁶ M⊙) are still elusive [1]. Recent James Webb Space Telescope discoveries of supermassive BHs in…

Dark lens candidates from Gaia Data Release 3 Open

K. Kruszyńska, Ł. Wyrzykowski, Krzysztof A. Rybicki, K. Howil, M. Jabłońska , et al. · 2024

Gravitational microlensing is a phenomenon that allows us to observe dark remnants of stellar evolution even if they no longer emit electromagnetic radiation. In particular, it can be useful to observe solitary neutron stars or stellar-mas…

Time-varying double-peaked emission lines following the sudden ignition of the dormant galactic nucleus AT2017bcc Open

E. J. Ridley, M. Nicholl, Charlotte Ward, P. K. Blanchard, R. Chornock , et al. · 2023

We present a pan-chromatic study of AT2017bcc, a nuclear transient that was discovered in 2017 within the skymap of a reported burst-like gravitational wave candidate, G274296. It was initially classified as a superluminous supernova, and …

Lens mass estimate in the Galactic disk extreme parallax microlensing event Gaia19dke Open

M. Maskoliūnas, Ł. Wyrzykowski, K. Howil, K. A. Rybicki, Paweł Zieliński , et al. · 2023

We present the results of our analysis of Gaia19dke, an extraordinary microlensing event in the Cygnus constellation that was first spotted by the {\gaia} satellite. This event featured a strong microlensing parallax effect, which resulted…

The Gaia alerted fading of the FUor-type star Gaia21elv Open

Z. Nagy, Sunkyung Park, P. Ábrahám, Á. Kóspál, Fernando Cruz-Sáenz de Miera , et al. · 2023

FU Orionis objects (FUors) are eruptive young stars, which exhibit outbursts that last from decades to a century. Due to the duration of their outbursts, and to the fact that only about two dozens of such sources are known, information on …

The Gaia alerted fading of the FUor-type star Gaia21elv Open

Z. Nagy, Sunkyung Park, P. Ábrahám, Á. Kóspál, Fernando Cruz-Sáenz de Miera , et al. · 2023

FU Orionis objects (FUors) are eruptive young stars, which exhibit outbursts that last from decades to a century. Due to the duration of their outbursts, and to the fact that only about two dozens of such sources are known, information on …

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