Kinematics of the structure of the active region in Orion-KL

The kinematics of the superfine structure of the active star-forming region in the dense molecular cloud Orion-KL has been investigated in the Н₂О maser emission for the period 1998–2003. It has been established that the surrounding gas inflows onto the disk and is transferred in a spiral trajectory to the center. An excess angular momentum as it is accumulated is carried away by a bipolar outflow; a highvelocity central flow surrounded by low-velocity components is formed. The outer low-velocity component observed at the detection limit has a diameter Ø₃ ≈ 4.5 AU, further out, Ø₂ ≈ 0.5 AU and Ø₁ ≈ 0.24 AU. The gas transfer velocity increases exponentially as the center is approached. The maser emission from the central flow is decisive. A rise in the velocity leads to a flow discontinuity and a reduction in the amount of inflowingmaterial and, accordingly, the emission level. The emission in the period under consideration was reduced exponentially for ~6 months, whereupon its restoration began.     

Structural peculiarities of the AGN object 1803+784

The structure of the AGN object 1803+784 has been investigated at a wavelength of 7 mm with a limiting angular resolution reaching 20 μas. The ejector nozzle surrounded by a ring structure, an accretion disk, has been identified. The nozzle size is ∼0.1 pc, the diameter of the ring structure is ∼1.4 pc, and its width is ∼0.25 pc. The reaction of the plasma flow produces a multimode precession responsible for the conical helical structure of the jet with a variable step and a curved axis. The viewing angle of the flow ejection is ∼40°. The central part of the ejected flow moving along the axis accelerates to a relativistic velocity. The apparent velocity reaches 12 s at a distance of ∼1 mas or ∼6 pc from the ejector. The outer part of the flow moves along a helix around a high-velocity component whose step is a factor of 4 smaller, because the longitudinal velocity is relatively low. The plasma is ejected almost toward the observer, as confirmed by its high brightness temperature T _b ≈ 8 × 10¹³ K and highly beamed emission. The polarized emission from the nozzle is axisymmetric. The orientation of the polarization of the flow along the whole length is aligned with the direction of its motion, suggesting the excitation of a ring magnetic field around it and self-focusing.     

Fine Structure of the Core of the Blazar OJ 287. III. Polarized Emission

This conclusive paper summarizes the results of our studies of the fine and superfine structure of the blazar OJ 287 at wavelengths of 7 mm and 2 cm in polarized emission with angular resolution is 20 μas. The orientation of the polarization of its fragments is almost orthogonal to the motion of the flows, suggesting that the magnetic field of the structures is oriented along the direction of the flow velocity. This is determined by the rotation of the flows—the excitation of ring currents and the generation of a solenoidal magnetic field, which applies both to the arms along which the surrounding matter is transferred to the center, the northern (m = 16%) and southern (m = 5%) ones, and to the ejected flows carrying away an excess angular momentum. The polarization level of the jet and counterjet flows reachesm = 15–20%and rises as one recedes fromthe nozzle due to a decrease in the optical depth of the fragments. The polarization level of the counterjet at the nozzle exit reaches 10%, while that of the jet is considerably lower. This is related to the location of the jet nozzle in the opposite direction relative to the observer, the influence of the screen. The special position refers to the nozzles. The polarization level is m - 2%. In the case of outbursts, the polarization increases with brightness, λ = 7 mm. At λ = 2 cm there is an inverse dependence. The spectral index of outbursts lies within the range α = 0–0.8.     

An accretion disk,a bipolar outflow,and an envelope—A structure that accompanies the formation of a protostar

We analyze the superfine structure of the supermaser H₂O emission region in Orion KL over the period 1979–1999. The angular resolution reached 0.1 mas, which corresponds to 0.045 AU at a distance to Orion KL of 450 pc. We determined the velocity of the local standard of rest, V_LSR = 7.65 km s^?1. The formation of a protostar is accompanied by a structure that consists of an accretion disk, a bipolar outflow, and a surrounding envelope. The disk is at the stage of separation into protoplanetary rings. The disk plane is warped like the brim of a hat. The disk is 27 AU in diameter and ～0.3 AU in thickness. The rings contain ice granules. Radiation and stellar wind sublimate and blow away the water molecules to form halos around the rings, maser rings. The radiation from the rings is concentrated in the azimuthal plane, and its directivity reaches 10^?3. The relative velocities of the rings located in the central part of the disk 15 AU in diameter correspond to rigid-body rotation, V_rot = ΩR. The rotation period is T ≈ 170 yr. The injector is surrounded by a toroidal structure 1.2 AU in diameter. The diameter of the injected flow does not exceed 0.05 AU. A highly collimated bipolar outflow with a diameter of ～0.1 AU is observed at a distance as large as 3 AU. Precession of the injector axis with a period of ～10 yr forms a spiral flow structure. The flow velocity is ～10 km s^?1. The kinetic energy of the accreting matter and the disk is assumed to be transferred to the bipolar outflow, causing the rotation velocity distribution of the rings to deviate from the Keplerian velocity. The surrounding envelope amplifies the emission from the structure at a velocity of 7.65 km s^?1 in a band of ～0.5 km s^?1 by more than two orders of magnitude, which determines the supermaser emission.     

The Seyfert Galaxy NGC 1275: Superfine Structure

Astronomy Letters - Based on VLBA observations (NRAO archive) at λ = 2 cm, we have constructed radio maps of the Seyfert galaxy NGC 1275 with a resolution of 25 µas, the epochs of...     

Fine Structure of the Core of the Blazar OJ 287-I

The fine structure of the active region, the bulge, of the blazar OJ 287 has been investigated with a resolution of 20 μas (0.1 pc) at a wavelength of 7 mm, the epochs of 2007–2017. The structure and kinematics correspond to a vortex nature. The surrounding matter, the plasma, is transferred to the center along two arms from opposite directions. The emerging excess angular momentum is carried away along the rotation axis by bipolar outflows, rotating coaxial tubes, in a direction X ≈ ?120? in the plane of the sky as it is accumulated. The central high-velocity bipolar outflow has a helical shape. The diameters of the low-velocity flows are ø1 ≈ 0.3 and ø2 ≈ 0.65 mas, or 1.4 and 3 pc, respectively. Ring currents whose tangential directions are observed as parallel chains of components are excited in the flow walls. The peak brightness temperature of the nozzle reaches Tb ≈ 1012?1013 K. A “disk” with a diameter ø ≈ 0.5 mas (≈2.2 pc) is observed by the absorption of synchrotron radiation. The disk is inclined to the plane of the sky at an angle of 60? in the jet direction. The fragments are seen from a distance of ～0.2 mas outside the absorption zone. The jet sizes exceed considerably the counterjet ones. An enhanced supply of plasma from the northern arm gives rise to an independent vortex 0.2 mas away from the central one in the NW direction. As in the first case, the helical central bipolar outflow is surrounded by a low-velocity component ø ≈ 0.28 mas in diameter with built-in ring currents. The jet is ejected in the direction X = ?50? in the plane of the sky. The jet orientation changes, X = ?130? at a distance of 1 mas. A high activity of the central and two side nozzles spaced 0.22 mas apart in the direction X = ?40? is occasionally observed simultaneously. The active region of the blazar is observed through an ionized medium, a screen, whose influence is significant even at a wavelength of 7 mm. The absorption and refraction of the transmitted emission in the screen affect the apparent brightness relative to the positions of the fragments.     

Kinematics of the active region of the quasar 3C 345

The fine structure of the quasar 3C 345 in polarized emission at 7 mm and 2 cm has been investigated. The kinematics is shown to correspond to an anticentrifuge: the thermal plasma of the surrounding space accretes onto the disk, flows to the center, and is ejected in the form of a rotating bipolar outflow that carries away the excess angular momentum as it accumulates. The bipolar outflow consists of a high-velocity central jet surrounded by a low-velocity component. The low-velocity flows are the rotating hollow tubes ejected from the peripheral part of the disk with a diameter ～Ø₁ = 2.2 pc and from the region Ø₂ = 1 pc. The high-velocity jet with a diameter Ø₃ = 0.2 pc is ejected from the central part of the disk, while the remnant falls onto the forming central body. The ejection velocity of the high-velocity flow is v ? 0.06c. At a distance up to ～1 pc, the jet accelerates to an apparent velocity v ～ 8c. Further out, uniform motion is observed within ～2 pc following which deceleration occurs. The jet structure corresponding to a conical diverging helix with an increasing pitch is determined by gasdynamic instability. The counterjet structure is a mirror reflection of the nearby part of the jet. The brightness temperature of the fragment of the high-velocity flow at the exit from the counterjet nozzle is T _b ≈ (10¹²?10¹³) K. The disk inclined at an angle of 60° to the plane of the sky shadows the jet ejector region. Ring currents observed in the tangential directions as parallel chains of components are excited in the rotating flows. The magnetic fields of the rotating bipolar outflow and the disk are aligned and oriented along the rotation axis. The translational motions of the jet and counterjet are parallel and antiparallel to the magnetic field, which determines their acceleration or deceleration. The quasar core is surrounded by a thermal plasma. The sizes of the HII region reach ～30 pc. The electron density decreases with increasing distance from the center from N _e ≈ 10⁸ to ≈10⁵ cm^?3. The observed emission from the jet fragments at the exit from the nozzle is partially absorbed by the thermal plasma, is refracted with increasing distance—moves with an apparent superluminal velocity, and decelerates as it goes outside the HII region.     

Fine Structure of the Core of the Blazar OJ 287. II. Wavelength 2 cm

We have continued our studies of the fine structure of the active region in the blazar OJ 287 at wavelength λ = 2cm with a resolution of 20 μas, the epochs of 1995–2017. We have identified fragments of two arms along which the surrounding plasma comes to the nozzle. The brightness temperature of the flows rises as the nozzle is approached to T_b ? 10¹² K. The high-velocity bipolar outflow surrounded by lowvelocity components carries away an excess angular momentum as it is accumulated. The high collimation and helicity of the flows are determined by rotation and precession, respectively. Ring currents responsible for the longitudinal magnetic fields are excited in the flows. The jet and counterjet are a mirror reflection of each other; the difference in sizes is determined by the acceleration/deceleration of the flows along/opposite to the magnetic field. The velocity of the high-velocity outflow is v ? 0.06 c. The brightness temperature of the nozzle reaches T_b ? 10¹⁴ K. The spectral index of the southern and northern nozzles is α ≈ 0.66 and ≈0.4, respectively; the difference is determined by absorption in the bulge. The separation between the nozzles is 12 μas or 0.05 pc. The central region of reduced brightness with a diameter ? ≈ 3.6 pc corresponds to the bulge inclined toward the jet at an angle of 65° to the plane of the sky. The counterjet is ejected toward the observer; the jet is ejected in the opposite direction and is visible outside the bulge from a distance of 1.5 pc. The structure and kinematics of the bulge correspond to a vortex nature. An enhanced supply of matter from the northern arm in the middle of 2000 increased the activity of the low-velocity nozzle. A secondary vortex located at a distance of 0.28 mas (1.3 pc) was formed. The high-velocity flow is ejected in a direction of ?110°.     

Active region of the nucleus of the blazar 3C 454.3

The superfine structure of the object 3C 454.3 has been investigated at λ = 7 mm in polarized emission. The kinematics of the structure is shown to correspond to a vortex. A spiral structure like an Archimedes spiral has been established in the accretion disk. The orbital velocity of the inflow exceeds considerably the radial velocity. The disk is oriented in the plane of the sky. The bipolar outflow ejection axis is directed toward the observer with a slight inclination to the east. The jet sizes exceed considerably the counterjet sizes. The jet is ejected in a direction opposite to the observer; its apparent separation from the nozzle is determined by the disk shadowing. The counterjet is directed toward the observer; the flow brightness temperature at the exit from the nozzle reaches T _b ≈ 10¹⁵ K. The jet has a spiral shape with an increasing pitch; the counterjet is a mirror reflection of the initial part of the jet. The incoming thermal plasma is accelerated and heated to relativistic temperatures as it is transferred along a spiral to the center. The orientation of the emission polarization plane changes along the flows due to a change in the ratio of the orbital and radial velocities, a change in the magnetic field orientation.     

Polarized emission from the ejector in Orion KL

The superfine structure of the active region in Orion KL has been investigated in the H₂O maser line at two epochs, December 23, 1998, and April 24, 1999, with an angular resolution as high as 0.01 mas. A bright central source, a bipolar outflow ejector with two nozzles spaced 0.008 mas apart, has been identified. The impact of the ejected flows causes precession of the rotation axis and gives rise to a jet structure in the shape of diverging helixes of opposite signs. The longitudinal velocities of the flows differ by 0.12 km s^?1. The flow emission at the exit from the nozzles is linearly polarized and oriented at an angle of 22° relative to the rotation axis or parallel to the flow velocities. Their brightness temperature exceeds T _b > 10¹⁸ K. The width of the emission line profiles is 0.43 km s^?1, their relative shift is ±0.06 km s^?1, and the orientations of the polarization planes differ by 45°, which determines the extraordinary rotation of the polarization plane, 25°/km s^?1.