Preliminary results of the alignment and Hartmann tests of the AZT-22 telescope

Aslan, Z.; Bikmaev, I.; Vitrichenko, E. A.; Gumerov, R. I.; Dembo, L. A.; Kamus, S. F.; Keskin, V.; Kızıloğlu, Ü.; Pavlinsky, M.; Panteleev, L. N.; Сахибуллин, Н. А.; Selam, S. O.; Sunyaev, R.; Khamitov, I.; Yaskovich, A.

doi:10.1134/1.1374679

Cited by 9 publications

(4 citation statements)

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“…Observations of SN 2014J were performed on the 1.5-m Russian-Turkish telescope RTT-150 (Aslan et al 2001) using time allocated to Kazan Federal University. The low-resolution spectroscopic mode of the TFOSC instrument was used.…”

Section: S P E C T Ro S C O P I C O B S E Rvat I O N S Data S U B T ...mentioning

confidence: 99%

The intermediate nebular phase of SN 2014J: onset of clumping as the source of recombination

Mazzali

Bikmaev

Sunyaev

et al. 2020

Monthly Notices of the Royal Astronomical Society

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At the age of about 1 yr, the spectra of most Type Ia supernovae (SNe Ia) are dominated by strong forbidden nebular emission lines of Fe ii and Fe iii. Later observations (at about 2 yr) of the nearby SN 2011fe showed an unexpected shift of ionization to Fe i and Fe ii. Spectra of the very nearby SN Ia 2014J at an intermediate phase (1–1.5 yr) that are presented here show a progressive decline of Fe iii emission, while Fe i is not yet strong. The decrease in ionization can be explained if the degree of clumping in the ejecta increases significantly at ∼1.5 yr, at least in the Fe-dominated zone. Models suggest that clumps remain coherent after about one year, behaving like shrapnel. The high density in the clumps, combined with the decreasing heating rate, would then cause recombination. These data may witness the phase of transition from relatively smooth ejecta to the very clumpy morphology that is typical of SN remnants. The origin of the increased clumping may be the development of local magnetic fields.

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Section: S P E C T Ro S C O P I C O B S E Rvat I O N S Data S U B T ...mentioning

confidence: 99%

The intermediate nebular phase of SN 2014J: onset of clumping as the source of recombination

Mazzali

Bikmaev

Sunyaev

et al. 2020

Monthly Notices of the Royal Astronomical Society

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“…Spectroscopic observations of 45 Her were obtained at the TÜBITAK National Observatory (TUG), Antalya with RTT150 (1.5-meter Russian-Turkish) telescope (Aslan et al 2001) and Coude Echelle Spectrometer (CES). Observations were carried out on 13 different nights in 2014, 2015, and 2018 with exposure times ranging from 20 to 70 min.…”

Section: Ces Spectroscopymentioning

confidence: 99%

Surface structure of 45 Hercules: An otherwise unremarkable Ap star with a surprisingly weak magnetic field

Kochukhov¹,

Mutlay²,

Amarsi³

et al. 2023

Preprint

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The origin of magnetic fields and their role in chemical spot formation on magnetic Ap stars is currently not understood. Here we contribute to solving this problem with a detailed observational characterisation of the surface structure of 45 Her, a weak-field Ap star. We find this object to be a long-period, single-lined spectroscopic binary and determine the binary orbit as well as fundamental and atmospheric parameters of the primary. We study magnetic field topology and chemical spot distribution of 45 Her with the help of the Zeeman Doppler imaging technique. Magnetic mapping reveals the stellar surface field to have a distorted dipolar topology with a surface-averaged field strength of 77 G and a dipolar component strength of 119 G -confirming it as one of the weakest well-characterised Ap-star fields known. Despite its feeble magnetic field, 45 Her shows surface chemical inhomogeneities with abundance contrasts of up to 6 dex. Of the four chemical elements studied, O concentrates at the magnetic equator whereas Ti, Cr and Fe avoid this region. Apart from this trend, the positions of Fe-peak element spots show no apparent correlation with the magnetic field geometry. No signs of surface differential rotation or temporal evolution of chemical spots on the time scale of several years were detected. Our findings demonstrate that chemical spot formation does not require strong magnetic fields to proceed and that both the stellar structure and the global field itself remain stable for sub-100 G field strengths contrary to theoretical predictions.

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“…During observations that began in September 2007, we used the CES attached to the RTT150 telescope at the TUG (see Aslan et al (2001) for RTT150 technical details and optical performance). The CES collects wavelengths in the interval from 3900 Å to 8700 Å, distributed over 68 spectral orders with an R = 40000 resolving power on a 1 K Â 1 K SAO-RAS CCD (pixel size: 16 lm) detector.…”

Section: Observational Setup and Data Reductionmentioning

confidence: 99%