Two epoch spectra-imagery of PV Cep outflow system

TL;DR

This study uses multi-epoch spectroscopic imaging to analyze the structure, kinematics, and proper motions of the HH 215 outflow from PV Cep, revealing new features and detailed velocity information about the jet and knots.

Contribution

It provides the first detailed proper motion and velocity measurements of HH 215 structures, including a newly-formed knot, using multi-epoch Fabry-Perot interferometry.

Findings

Identified a high-velocity inner channel aligned with the outflow axis.

Discovered a new HH knot formed during PV Cep's 1976-1977 maximum.

Estimated the outflow length as approximately 0.2 pc and the bipolar outflow as 3.6 pc.

Abstract

We continue to study the structure and kinematics of HH flows. Herbig-Haro (HH) flows exhibit large variety of morphological and kinematical structures. Both proper motion (PM) and radial velocity investigations are essential to understand the physical nature of such structures. We investigate the kinematics and PM of spectrally separated structures in the PV Cep HH flow HH 215. We present the observational results obtained with a 6 m telescope (Russia) using the SCORPIO multi-mode focal reducer with scanning Fabry-Perot interferometer. Two epochs of the observations of the PV Cep region in H$\alpha$ and [SII] emission (2003 and 2020-2021) allowed us to study the morphology of HH 215 jet in detail and to measure the PM and the radial velocities for its inner structures. Already known emission knots in the HH 215 flow and new features were studied. Moreover, a newly-formed HH knot was revealed, presumably formed during the large maximum of PV Cep star in 1976-1977. We found the high-velocity inner channel in the HH 215 ionized outflow, oriented accordingly to the mean direction of the whole HH outflow and the axis of the symmetry of the reflection nebula. The HH-knots located along the axis of the high-velocity channel have a position angle coinciding with its axis (abut 325$^{\circ}$), however other ones have completely different value (about 25$^{\circ}$), which supports the idea that those knots are formed by oblique shocks. We derived the value of i $\approx$ 30$^{\circ}$$\pm$ 5$^{\circ}$ for the inclination angle between the flow axis and the line of sight. The total length of HH 215 outflow should be about 0.2 pc, and the full length of the bipolar outflow from PV Cep (HH 315 + HH 215) can be estimated as 3.6 pc, assuming that it more or less keeps the same inclination angle.