_version_ 1866908349907337216
author Nagy, Zsófia
Kóspál, Ágnes
Ábrahám, Péter
Giannini, Teresa
Kun, Mária
Gangi, Manuele
de Miera, Fernando Cruz-Sáenz
Kuhn, Michael
Siwak, Michał
Szilágyi, Máté
Fiorellino, Eleonora
Antoniucci, Simone
Biazzo, Katia
Bódi, Attila
Bora, Zsófia
Cseh, Borbála
Dróżdż, Marek
Horti-Dávid, Ágoston
Joó, András Péter
Kalup, Csilla
Kotysz, Krzysztof
Kriskovics, Levente
Marton, Gábor
Mikołajczyk, Przemysław J.
Nisini, Brunella
Pál, András
Seli, Bálint
Sódor, Ádám
Szabados, László
Szabó, Norton Olivér
Szabó, Zsófia Marianna
Szakáts, Róbert
Varga, Vázsony
Vinkó, József
Wyrzykowski, Łukasz
Zieliński, Paweł
author_facet Nagy, Zsófia
Kóspál, Ágnes
Ábrahám, Péter
Giannini, Teresa
Kun, Mária
Gangi, Manuele
de Miera, Fernando Cruz-Sáenz
Kuhn, Michael
Siwak, Michał
Szilágyi, Máté
Fiorellino, Eleonora
Antoniucci, Simone
Biazzo, Katia
Bódi, Attila
Bora, Zsófia
Cseh, Borbála
Dróżdż, Marek
Horti-Dávid, Ágoston
Joó, András Péter
Kalup, Csilla
Kotysz, Krzysztof
Kriskovics, Levente
Marton, Gábor
Mikołajczyk, Przemysław J.
Nisini, Brunella
Pál, András
Seli, Bálint
Sódor, Ádám
Szabados, László
Szabó, Norton Olivér
Szabó, Zsófia Marianna
Szakáts, Róbert
Varga, Vázsony
Vinkó, József
Wyrzykowski, Łukasz
Zieliński, Paweł
contents 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 2023 outburst. We obtained optical and near-infrared photometry and spectroscopy to probe the variation of the physical properties of Gaia23bab during its recent outburst. We also collected archival photometry to study a previous outburst of the star. We used several accretion tracers, including the Ca II triplet, He I, and various hydrogen lines from the Paschen and Brackett series, to measure the accretion rate during the outburst. The accretion rate is consistent with $\sim 2.0 \times 10^{-7} M_\odot$ $\rm{yr}^{-1}$. Comparing the line fluxes of the hydrogen Brackett series to predictions of Case B theory suggests excitation temperatures of 5000 - 10000 K and electron densities of $10^9$-$10^{10}$ cm$^{-3}$. Comparison to the predictions of a model for T Tauri stars revealed that the fluxes of the Balmer series are consistent with temperatures of 5000 - 12500 K and a hydrogen density of $10^8$ cm$^{-3}$, while the fluxes of the Paschen series are consistent with temperatures in the range between 10000 and 12500 K and a hydrogen density of $10^{11}$ cm$^{-3}$. The derived temperatures and densities confirm that Gaia23bab is a prototypical EXor, not only due to its accretion rate, but also based on the best fit temperatures and densities revealed by the detected hydrogen lines.
format Preprint
id arxiv_https___arxiv_org_abs_2505_02227
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle The 2023 outburst of the Gaia alerted EXor Gaia23bab
Nagy, Zsófia
Kóspál, Ágnes
Ábrahám, Péter
Giannini, Teresa
Kun, Mária
Gangi, Manuele
de Miera, Fernando Cruz-Sáenz
Kuhn, Michael
Siwak, Michał
Szilágyi, Máté
Fiorellino, Eleonora
Antoniucci, Simone
Biazzo, Katia
Bódi, Attila
Bora, Zsófia
Cseh, Borbála
Dróżdż, Marek
Horti-Dávid, Ágoston
Joó, András Péter
Kalup, Csilla
Kotysz, Krzysztof
Kriskovics, Levente
Marton, Gábor
Mikołajczyk, Przemysław J.
Nisini, Brunella
Pál, András
Seli, Bálint
Sódor, Ádám
Szabados, László
Szabó, Norton Olivér
Szabó, Zsófia Marianna
Szakáts, Róbert
Varga, Vázsony
Vinkó, József
Wyrzykowski, Łukasz
Zieliński, Paweł
Solar and Stellar Astrophysics
Astrophysics of Galaxies
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 2023 outburst. We obtained optical and near-infrared photometry and spectroscopy to probe the variation of the physical properties of Gaia23bab during its recent outburst. We also collected archival photometry to study a previous outburst of the star. We used several accretion tracers, including the Ca II triplet, He I, and various hydrogen lines from the Paschen and Brackett series, to measure the accretion rate during the outburst. The accretion rate is consistent with $\sim 2.0 \times 10^{-7} M_\odot$ $\rm{yr}^{-1}$. Comparing the line fluxes of the hydrogen Brackett series to predictions of Case B theory suggests excitation temperatures of 5000 - 10000 K and electron densities of $10^9$-$10^{10}$ cm$^{-3}$. Comparison to the predictions of a model for T Tauri stars revealed that the fluxes of the Balmer series are consistent with temperatures of 5000 - 12500 K and a hydrogen density of $10^8$ cm$^{-3}$, while the fluxes of the Paschen series are consistent with temperatures in the range between 10000 and 12500 K and a hydrogen density of $10^{11}$ cm$^{-3}$. The derived temperatures and densities confirm that Gaia23bab is a prototypical EXor, not only due to its accretion rate, but also based on the best fit temperatures and densities revealed by the detected hydrogen lines.
title The 2023 outburst of the Gaia alerted EXor Gaia23bab
topic Solar and Stellar Astrophysics
Astrophysics of Galaxies
url https://arxiv.org/abs/2505.02227