Spectroscopic observations of the classical nova TCP J17525020-2024150

ATel #16135; Olivier Garde, Stephane Charbonnel, Pascal Le Du, Lionel Mulato, Thomas Petit (2SPOT, Chile; ARAS Group), Andrew Pearce (Nedlands, Western Australia), Steve Shore (Univ. of Pisa)
on 16 Jul 2023; 15:32 UT
Distributed as an Instant Email Notice Novae
Credential Certification: S. N. Shore (shore@df.unipi.it)

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We report early spectroscopic observations of transient TCP J17525020-2024150, reported in outburst by Andrew Pearce on 2023 Jul 15.459 (CBAT Transient follow-up reports). Spectra were obtained on 2023 Jul 15.95 and 16.04 with exposure times of 9700 sec with the 2SPOT Alpy600 and eShel spectrographs (see ATel #16004) at resolutions of about 1000 (3600-7800A, SNR ~ 30) and 11000 (3970-7600A, SNR ~ 10) with exposure times of 3000 and 9100 sec, respectively. The source is a classical nova in the early, optically thick stage of expansion. The interstellar Na I D lines have equivalent widths of 1.7A (D2) and 1.6 (D1), with multiple partly resolved components at v(LSR) = +20, +87, +132 km/s, consistent with the bulk of the 21 cm profile from LAB. This implies N_H ~ 4E21/cm^2 and E(B-V) ~0.65+/-0.1 (2sig). This is compatible with the D line ratio but about 1/10 the value derived for the likely optical counterpart, IGR J17528-2022 (Hare et al. 2021, ApJ, 914, 85), suggesting that the x-rays were mainly extinguished within the system during the Chandra/NuSTAR observations. Several DIB features appear to be measurable, 5870 (EW~0.58+/-0.05A), 6614 (0.24+/-0.05A). The Balmer lines show P Cyg profiles with multiple components in absorption at vrad(Hel) ~ -4100+/-50 (vmax ~ -4500 km/s) and -2900+/-50 km/s (Halpha-Hgamma, FWZI ~ 400 km/s for absorption) and nearly symmetrically situated emission peaks within a broader profile whose central peak is at 0.1+/-10 km/s. The redward emission wing extends to about +4500 km/s. There may be He I 5876 absorption at the Halpha velocity, but there is no emission component. Fe II 5018, 5169 and Si II 6347/70 (among others) are present with an absorption feature at around -2900 km/s, consistent with the lower velocity seen on the Balmer lines. The emission on these lines is extremely weak if present. The profiles are consistent with an aspherical ejecta structure, perhaps at comparatively low inclination to the line of sight. The velocities are high for classical novae but not exceptional. No [O I] is detected, the spectra do not reach the red O I lines or the Ca II triplet so longer wavelength observations are strongly advised.

ARAS Spectral Database