Two ATel describe the emergence of high ionized lines (He II, [Fe VI], [Fe VII], [Ar III]
Continuing ARAS Group spectroscopic monitoring of RS Oph: appearance of high ionization lines
ATel #14881; S. N. Shore (Univ. of Pisa), F. Teyssier, O. Thizy (ARAS Group)
on 28 Aug 2021; 12:30 UT
This is an update on the continuing spectroscopic monitoring of RS Oph by the ARAS group medium resolution (resolution above 9000, covering around 3900 to 8900A). Here we report only recent results from the echelle spectra. A large number of lower resolution, from about 200 to 1500, are also being accumulated (ATel#14868 and cited previous). The details of instruments and telescope apertures are provided on the website (
https://aras-database.github.io/database/rsoph.html). For comparison, see
https://ui.adsabs.harvard.edu/abs/2008A ... E/abstract for an overview of the 2006 outburst. All absorption has now vanished around Aug 25.0 from the Balmer profiles, the narrow wind P Cyg absorption at -36 km/s now shows weak, narrow emission on Halpha. The Halpha profile also shows a weak, extended wing to \vrad| ~ 3000 km/s with the maximum |vrad| ~ 2000 km/s at about twice the continuum level.; the line profile is steeper on the blue side. He II 4686, 5411 are both present, HWZI ~ 1000 km/s and symmetric profiles. This contrasts with the He I profiles, especially 6678, that show an emission peak at +230 km/s; this is also present on the Balmer lines, O I 7774, 8446, and is different from the [N II] 5755 peak (-37 km/s). This peak is not present on either optical He II profile or N III 4636A, which is now stronger than He II 4686. [Fe VI] 5276 shows a narrow feature, like [N II] and at -44 km/s, as does [Fe VII] 6087; the latter also appears to show a broader feature with maximum |vrad| ~ 640 km/s (HWZI) . The narrow component may have been present as early as Aug. 17. [Fe VII] 5720 may also show a weak narrow component after Aug. 25. If due to photoionization, it indicates flux at or above about 0.1 KeV so there may already be a strong soft source that is simply too absorbed by the still mainly neutral wind to be directly detectable. [Fe VI] 5276 may also have been present earlier but was more likely Fe II 5275. [Ar III] 7135 is likely present as a very weak, similarly narrow feature as early as Aug. 17.
And a short fading of He II wich almost desappared during one day.
This behavior of He II was totally unforseen (and not detected during former outburst) and very strange in the current.
This fading was so surprising/understadable that we use low resolution in order to verify.
It has been established thanks to high cadency, daily monitoring of the 2021 outburst.
A great moment!
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
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.
The evolution of He II from echelle spectra secured by Joan Guarro and François Teyssier
Rise, fading (red) and recovery (blue)
- rsoph_20210821_916_F Teyssier.png (90.67 KiB) Viewed 7533 times
The same in wl space with also the variations of NII 4640 which follows He II, to a lesser degree
- rsoph_20210821_916_F TeyssierWL.png (128.26 KiB) Viewed 7533 times
Let's go on the good job
François