ARAS Group monitoring of RS Oph 2021: Rapid profile variations of He II detected
ATel #14883; S. N. Shore (Univ. of Pisa), F. Teyssier, J. Guarro, H. Allen, V. Lecocq, K. Shank, P. Velez (ARAS Group)
on 29 Aug 2021; 00:36 UT
Credential Certification: S. N. Shore (shore@df.unipi.it)
In the last two days the He II 4686,5411A lines have dramatically altered in both strength and profile, detected with optical grating and echelle spectra (observers and nstruments are available at the ARAS Database website). As reported in ATel#14881, on Aug. 25.8 both lines were present with roughly symmetric profiles and |vrad,max| ~ -1100 km/s. On Aug. 26.8 the profiles were similar but about 1/2 the previous normalized flux. The profile now, Aug. 28.8, has < 1/10 the relative intensity and virtually no emission associated with the component centered at +270 km/s (+10 < vrad < 1300 km/s). Notably, the fine structure peaks on all He I profiles at around -240 km/s and -20 km/s are also present on He II and its blue wing extends to vrad ~ -1200 km/s, like He I (the wing of Hbeta extends to -2200 km/s). In this same time period, the O I 7772 A component shows emission confined to the same velocity interval as the He II emission deficit, although O I 8446 A shows a similar profile to the other permitted lines, including e.g., Fe II 5018, 5169 A. Although weakened in relative flux, N III 4636 has otherwise not changed from our previous observations. The only significant structural change is in the ionized He profiles. We urge continued, high cadence spectroscopic monitoring; all spectra described here are available through the ARAS database.
ARAS database: RS Oph spectra
