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Wyszukujesz frazę "Sefako, R." wg kryterium: Autor


Wyświetlanie 1-7 z 7
Tytuł:
Gaia20bdk : new FU Ori-type star in the Sh 2-301 star-forming region
Autorzy:
Krzesiński, Jerzy
Szilágyi, M.
Cruz-Sáenz de Miera, F.
Siwak, Michał
Pál, A.
Cseh, B.
Vinkó, J.
Kun, M.
Wyrzykowski, Ł.
Szabó, Zs. M.
Gromadzki, M.
Kalup, Cs.
Nagy, Z.
Sefako, R.
Fiorellino, E.
Joó, A.
Marton, G.
Szakáts, R.
Kriskovics, L.
Sódor, Á.
Ábrahám, P.
Potter, S. B.
Zieliński, P.
Lucas, P. W.
Horti-Dávid, Á.
Zakrzewski, B.
Kóspál, Á.
Worters, H. L.
Buckley, D. A. H.
Giannini, T.
Ogłoza, W.
Opis:
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. Methods. We used public-domain archival photometry to characterise the quiescent phase and to establish the major physical parameters of the progenitor. We used our own optical and infrared (IR) photometry and spectroscopy, along with data from the public domain, to study the outburst. Results. Gaia20bdk is a member of the Sharpless 2-301 star-forming region, at a distance of 3.3 kpc. The progenitor is a rather massive 2.7 ± 0.5 M$_{\odot}$, G7-type Class I young star, with an effective temperature of 5300$_{-300}^{+500}$ K and bolometric luminosity of 11 ± 2 L$_{\odot}$. The optical and IR photometric and spectroscopic data obtained during the outburst reveal a variety of signatures commonly found in classical FU Ori-type stars (FUors). Our disc modelling gives a bolometric luminosity of 100 − 200 L$_{\odot}$ and mass accretion rate of 1 − 2 $\times$ 10$^{−5}$ M$_{\odot}$ yr$^{-1}$, also confirming the object’s FUor classification. Further monitoring is necessary to track the light changes, accretion rate, and spectral variations, as well as to understand the mechanisms behind the disc flickering.
Dostawca treści:
Repozytorium Uniwersytetu Jagiellońskiego
Artykuł
Tytuł:
Wavelength-resolved reverberation mapping of quasar CTS C30.10 : dissecting Mg II and Fe II emission regions
Autorzy:
Martinez-Aldama, Mary Loli
Sobrino Figaredo, Catalina
Hryniewicz, Krzysztof
Zajaček, Michal
Worters, Hannah L.
Udalski, Andrzej
Przyłuski, Robert
Czerny, Bożena
Kumar Jaiswal, Vikram
Haas, Martin
Trzcionkowski, Piotr
Olejak, Aleksandra
Rałowski, Mateusz
Panda, Swayamtrupta
Prince, Raj
Śniegowska, Marzena
Genade, Anja
Karas, Vladimir
Naddaf, Mohammad-Hassan
Sefako, Ramotholo R.
Jacek Sarna, Marek
Bilicki, Maciej
Bronikowski, Mateusz
Opis:
Context. We present the results of the reverberation monitoring of the Mg II broad line and Fe II pseudocontinuum for the luminous quasar CTS C30.10 (z = 0.90052) with the Southern African Large Telescope in 2012–2021. Aims. We aimed at disentangling the Mg II and UV Fe II variability and the first measurement of UV Fe II time delay for a distant quasar. Methods. We used several methods for the time-delay measurements and determined the Fe II and Mg II time delays. We also performed a wavelength-resolved time delay study for a combination of Mg II and Fe II in the 2700–2900 Å rest-frame wavelength range. Results. We obtain a time delay for Mg II of 275.5$_{-19.5} ^{+12.4}$ days in the rest frame, and we have two possible solutions of 270.0$_{-25.3} ^{+13.8}$ days and 180.3$_{-30.0} ^{+26.6}$ in the rest frame for Fe II. Combining this result with the old measurement of Fe II UV time delay for NGC 5548, we discuss for first time the radius-luminosity relation for UV Fe II with the slope consistent with 0.5 within the uncertainties. Conclusions. Because the Fe II time delay has a shorter time-delay component but the lines are narrower than Mg II, we propose that the line-delay measurement is biased toward the part of the broad line region (BLR) facing the observer. The bulk of the Fe II emission may arise from the more distant BLR region, however, the region that is shielded from the observer.
Dostawca treści:
Repozytorium Uniwersytetu Jagiellońskiego
Artykuł
Tytuł:
Wavelength-resolved reverberation mapping of intermediate-redshift quasars HE 0413-4031 and HE 0435-4312 : dissecting Mg II, optical Fe II, and UV Fe II emission regions
Autorzy:
Sobrino Figaredo, Catalina
Olejak, Aleksandra
Martinez-Aldama, Mary Loli
Rałowski, Mateusz
Udalski, Andrzej
Haas, Martin
Hryniewicz, Krzysztof
Prince, Raj
Panda, Swayamtrupta
Pietrzyński, Grzegorz
Worters, Hannah L.
Sarna, Marek Jacek
Trzcionkowski, Piotr
Genade, Anja
Przyłuski, Robert
Bilicki, Maciej
Bronikowski, Mateusz
Kozłowski, Szymon
Śniegowska, Marzena
Karas, Vladimir
Czerny, Bożena
Kumar Jaiswal, Vikram
Średzińska, Justyna
Pandey, Ashwani
Sefako, Ramotholo R.
Zajaček, Michal
Naddaf, Mohammad-Hassan
Opis:
Context. We present the wavelength-resolved reverberation mapping (RM) of combined Mg II and UV Fe II broad-line emissions for two intermediate-redshift (z ∼ 1), luminous quasars, HE 0413-4031 and HE 0435-4312, monitored by the Southern African Large Telescope (SALT) and 1m class telescopes between 2012 and 2022. Aims. Using a wavelength-resolved technique, we aim to disentangle the Mg II and Fe II emission regions and to build a radius–luminosity (R–L) relation for UV Fe II emission, which has so far remained unconstrained. Methods. We applied several time-delay methodologies to constrain the time delays for total Mg II and Fe II emissions. In addition, wavelength-resolved RM is performed to quantify the inflow or outflow of broad-line region (BLR) gas around the supermassive black hole and to disentangle the emission and the emitting regions based on lines produced in proximity to each other. Results. The mean total FeII time delay is nearly equal to the mean total MgII time delay for HE 0435-4312, suggesting the co-spatiality of their emission regions. However, in HE 0413-4031, the mean FeII time delay is found to be longer than the mean MgII time delay, suggesting that FeII emission is produced at greater distances from the black hole. The UV FeII R–L relation is updated with these two quasars (now four in total) and compared with the optical FeII relation (20 sources), which suggests that the optical FeII emission region is located further than the UV FeII region by a factor of 1.7–1.9, that is, R$_{FeII-opt}$ ∼ (1.7 − 1.9)R$_{FeII-UV}$. Conclusion. Wavelength-resolved reverberation is an efficient way to constrain the geometry and structure of the BLR. We detected a weak pattern in the time delay versus wavelength relation, suggesting that the MgII broad line originates from a region slightly closer to the SMBH than the UV FeII pseudo continuum, although the difference is not very significant. Comparison of MgII, UV, and optical FeII R–L relations suggests that the difference may be greater for lower-luminosity sources, possibly with the MgII emission originating further from the SMBH. In the future, more RM data will be acquired, allowing better constraints on these trends, in particular the UV FeII R–L relation.
Dostawca treści:
Repozytorium Uniwersytetu Jagiellońskiego
Artykuł
    Wyświetlanie 1-7 z 7

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