The spectroscopy of TCP J12355222+2755559

ATel #14460; A. Vinokurov; A. F. Valeev; Yu. Solovyeva (SAO RAS)
on 15 Mar 2021; 19:52 UT
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Credential Certification: Azamat Valeev (azamat@sao.ru)

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We present the result of the spectroscopy TCP J12355222+2755559 (=AT 2016blu), which were carried out using the 6-m telescope equipped with the SCORPIO spectrograph on Mar 15 2021 (15-03-2021, MJD=59288.01). The new outburst of the object were discovered on Mar 7, 2021 (http://www.cbat.eps.harvard.edu/unconf/followups/J12355222+2755559.html), when the object had U magnitude 16.8. Most probably the transient belongs to the SN-imposters, several outbursts were detected during last ten years (Atels #3865, #6303, #8755). The analysis of 24-06-2014 spectrum made by P. Sheehan at al (Atel #6303) revealed the strong relatively narrow lines with P Cyg profiles of the Balmer series. The expansion velocity ~700 km/s was estimated from the absorption components. Moreover the similar P Cyg profile was detected for HeI 5876 line. The unresolved [S II] 6716,6731 and [O III] 4959,5007 were found in the spectrum, those probably due to the HII region surrounded this transient. Our spectrum covers 3600-5400 ÅÅ with the spectral resolution about 5.5 Å. The weather was not stable and on our acquisition images with ~3 arcsec seeing the photometry of the object is unmeasurable. On our spectrum we clearly see the lines of Balmer series with complex P Cyg profiles. The emission lines have the narrow components (which have FWHM similar to the spectral resolution) and broad components (FWHM ~1400 km/s). The absorption components of the Hβ and Hγ lines have double-peaked shape, similar to profiles of 2009-OT1 (Pastorello et al., 2010, MNRAS, 408, 181) during 2009 outburst. We measure the difference between the velocities of two peaks ~2800 km/s. The broad wings of the absorption feature extend up to velocity 5800 km/s. If we take into account that ratio between the terminal velocity and the edge velocity about 0.8 (following the Pastorello et al., 2010), as the result we will get the terminal velocity about 4600 km/s. Our spectrum revealed also the weak lines of the He I and ionized iron. We measure the FWHM of the profiles on the column along the slit near the Hβ, [OIII] 5007, [OII] 3727 lines and continuum - the spatial profiles of oxygen lines occur broader. This fact confirms that the largest parts of these Balmer emissions belong to the transient and various oxygen lines originate from the HII region.

J12355222+2755559 BTA 6-m spectrum