scholarly journals FLASHING: New high-velocity H2O masers in IRAS 18286−0959

2020 ◽  
Vol 72 (4) ◽  
Author(s):  
Hiroshi Imai ◽  
Yuri Uno ◽  
Daichi Maeyama ◽  
Ryosuke Yamaguchi ◽  
Kei Amada ◽  
...  
Keyword(s):  
High Velocity ◽  
Stellar System ◽  
Line Of Sight ◽  
Expansion Velocity ◽  
Dense Gas ◽  
Good Opportunity ◽  
Maser Emission ◽  
Bipolar Outflow ◽  
Systemic Velocity ◽  
Rapid Deceleration

Abstract We discovered new high-velocity components of H2O maser emission in one of the “water fountain” sources, IRAS 18286−0959, which has been monitored using the Nobeyama 45 m telescope in the FLASHING (Finest Legacy Acquisitions of SiO- and H2O-maser Ignitions by Nobeyama Generation) project since 2018 December. The maser spectra show new components with extremely high expansion velocities (>200 km s−1 projected in the line of sight), some of which are located symmetrically in the spectrum with respect to the systemic velocity. They were also mapped with KaVA (KVN and VERA Combined Array) in 2019 March. We located some of these maser components closer to the central stellar system than other high-velocity components (50–200 km s−1) that have been confirmed to be associated with the known bipolar outflow. The new components would have flashed in the fast collimated jet at a speed of over 300 km s−1 (soon) after 2011 when they had not been detected. The fastest of the new components seem to indicate rapid deceleration in these spectra; however, our present monitoring is still too sparse to unambiguously confirm it (up to 50 km s−1 yr−1) and too short to reveal their terminal expansion velocity, which will be equal to the expansion velocity that has been observed ($v$exp ∼ 120 km s−1). Future occurrences of such extreme-velocity components may provide a good opportunity to investigate possible recurrent outflow ignitions. Thus, the sculpture of the parental envelope will be traced by the dense gas that is entrained by the fast jet and exhibits spectacular distributions of the relatively stable maser features.

scholarly journals Dynamical Models of the Maser in NGC 4258

1997 ◽  
Vol 159 ◽  
pp. 402-405
Author(s):  
J.M. Moran
Keyword(s):  
Linear Dependence ◽  
High Velocity ◽  
Major Axis ◽  
Line Of Sight ◽  
Velocity Versus ◽  
Dynamical Models ◽  
Maser Emission ◽  
Systemic Velocity ◽  
The Galaxy ◽  
Dynamical Connection

The presence of two quasars symmetrically displaced from the nucleus of the galaxy NGC 4258 (Pietsch et al. 1994) has given rise to some speculation that they might have some dynamical connection with the high-velocity maser emission seen in the nucleus (Burbidge 1996; Ozernoy 1996). The case that the masers define a simple Keplerian disk is very compelling; nonetheless, it is instructive to investigate whether any other dynamical models could fit the available data.The evidence that the masers define a thin Keplerian disk can be found in Miyoshi et al. (1995) and Moran et al. (1995). Some of the relevant data are shown elsewhere in this volume (Fig. 2 of Greenhill’s paper). The basic analysis is as follows. The features near the systemic velocity of 470km s−1 show a linear dependence of line-of-sight velocity versus distance along the major axis, while the redshifted and blueshifted high-velocity features show a nearly Keplerian dependence with distance.

scholarly journals H2O maser emission from the Seyfert 2 galaxy IC 2560: evidence for a super-massive black hole and a probe for mass-accretion rate

2002 ◽  
Vol 206 ◽  
pp. 400-403
Author(s):  
Yuko Ishihara ◽  
Naomasa Nakai ◽  
Naoko Iyomoto ◽  
Kazuo Makishima ◽  
Phil Diamond ◽  
...  
Keyword(s):  
Black Hole ◽  
High Velocity ◽  
Accretion Rate ◽  
Rotating Disk ◽  
Massive Black Hole ◽  
Central Mass ◽  
Maser Emission ◽  
Mass Accretion Rate ◽  
Systemic Velocity ◽  
Velocity Drift

Our observations of H2O masers have detected some high-velocity features and a secular velocity drift of the systemic features in the Seyfert 2 Galaxy IC 2560. The high-velocity features were blue- and red-shifted from the systemic velocity of 220-420 km s−1 and 210-350 km s−1, respectively. The velocity of the systemic features drifted at a secular rate of 2.62 km s−1 yr−1. Assuming the existence of a compact rotating disk as in NGC 4258, IC 2560 possesses a nuclear disk with inner and outer radii of 0.07 pc and 0.26 pc, respectively, and a confined mass of 2.8 × 106M⊙ at the center, making the central density > 2.1 × 109M⊙ pc−3. Such a dense object cannot be a cluster of stars, and this strongly suggests that the central mass is a super-massive black hole. Since the 2-10 keV luminosity of IC 2560 is 1 × 1041 erg s−1, the mass accretion rate of the suggested black hole must be 2 × 10−5M⊙ yr−1.

scholarly journals A flaring megamaser in Mrk 348

2002 ◽  
Vol 206 ◽  
pp. 434-437 ◽  
Author(s):  
Alison B. Peck ◽  
Heino Falcke ◽  
Christian Henkel ◽  
Karl M. Menten ◽  
Yoshiaki Hagiwara ◽  
...  
Keyword(s):  
High Velocity ◽  
Strong Line ◽  
Maser Emission ◽  
Systemic Velocity

We report new observations of the H2O megamaser in the Seyfert 2 galaxy Mrk 348. Following our initial detection in 2000 March using the Effelsberg 100 m telescope, a re-analysis of previous data on this source indicates that the maser was present but only marginally detectable in late 1997. Monitoring through late 2000 shows that the maser has again decreased to its original level. The H2O line is redshifted by ∼130 km s−1 with respect to the systemic velocity, is extremely broad, with a FWHM of 130 km s−1, and has no detectable high velocity components within 1500 km s−1 on either side of the strong line. Followup VLBA observations show that the maser emission emanates entirely from a region ≤0.25 pc in extent, toward the base of the radio jet.

scholarly journals A Supermassive Object in the Nucleus of NGC 4258?

1995 ◽  
Vol 10 ◽  
pp. 531-534
Author(s):  
L.J. Greenhill ◽  
D.R. Jiang ◽  
J.M. Moran ◽  
M.J. Reid ◽  
K.-Y. Lo ◽  
...  
Keyword(s):  
Time Series ◽  
High Velocity ◽  
Major Axis ◽  
Line Of Sight ◽  
Spectral Features ◽  
Systemic Velocity

AbstractVLBI images of the H2O megamaser in NGC 4258 and a time series of spectra taken over several years combine to make a compelling case that there is a compact molecular disk associated with a supermassive object in the nucleus of this galaxy. The images of the maser in the velocity rangenear the systemic velocity show a highly elongated structure with a major axis of about 0.009 pc, along which the gradient in line-of-sight velocity is essentially a constant of 7970 ± 40 km s-1 pc-1. The observed acceleration of these spectral features by about 6-11 km s-1 yr-1, the presence of high-velocity maser satellite emission, and the VLBI results suggest emission from a disk of diameter0.2 pc, rotating with a velocity of ~800 Km s-1, bound by a mass of 1.5×107 M⊙ and denisty of ≳3.6×109 M⊙ pc-3

scholarly journals High-velocity interstellar absorption associated with the supernova remnant W28

2020 ◽  
Vol 495 (3) ◽  
pp. 2909-2920 ◽  
Author(s):  
Adam M Ritchey
Keyword(s):  
High Velocity ◽  
Molecular Cloud ◽  
Supernova Remnant ◽  
Line Emission ◽  
Line Of Sight ◽  
Interstellar Gas ◽  
Lower Velocity ◽  
North East ◽  
The North ◽  
Visible Wavelengths

ABSTRACT We present an analysis of moderately high-resolution optical spectra obtained for the sightline to CD−23 13777, an O9 supergiant that probes high-velocity interstellar gas associated with the supernova remnant W28. Absorption components at both high positive and high negative velocity are seen in the interstellar Na i D and Ca ii H and K lines towards CD−23 13777. The high-velocity components exhibit low Na i/Ca ii ratios, suggesting efficient grain destruction by shock sputtering. High column densities of CH+, and high CH+/CH ratios, for the components seen at lower velocity may be indicative of enhanced turbulence in the clouds interacting with W28. The highest positive and negative velocities of the components seen in Na i and Ca ii absorption towards CD−23 13777 imply that the velocity of the blast wave associated with W28 is at least 150 km s−1, a value that is significantly higher than most previous estimates. The line of sight to CD−23 13777 passes very close to a well-known site of interaction between the supernova remnant and a molecular cloud to the north-east. The north-east molecular cloud exhibits broad molecular line emission, OH maser emission from numerous locations, and bright extended GeV and TeV γ-ray emission. The sightline to CD−23 13777 is thus a unique and valuable probe of the interaction between W28 and dense molecular gas in its environs. Future observations at ultraviolet and visible wavelengths will help to better constrain the abundances, kinematics, and physical conditions in the shocked and quiescent gas along this line of sight.

scholarly journals EVN and MERLIN observations of an OH maser ring and a starburst continuum in III Zw 35

2002 ◽  
Vol 206 ◽  
pp. 426-429
Author(s):  
Ylva M. Pihlström ◽  
John E. Conway ◽  
Roy S. Booth
Keyword(s):  
High Sensitivity ◽  
Ring Structure ◽  
Line Of Sight ◽  
Diffuse Emission ◽  
Maser Emission ◽  
Physical Conditions ◽  
Vlbi Observations ◽  
Geometrical Effects ◽  
Western Side ◽  
Luminous Infrared Galaxy

We report on high-sensitivity EVN and MERLIN observations of the OH maser emission and continuum in the luminous infrared galaxy III Zw 35. Earlier VLBI observations have shown two compact maser clumps containing 40%–50% of the single-dish flux. In addition to these compact masers, we detect more diffuse maser emission which lies in a clear ring structure of radius r ∼ 22 pc. The ring appears inclined to the line of sight and the compact masers occur at the tangent points. This structure suggests that the compact and diffuse masers appear different because of geometrical effects and not pumping or other physical conditions. Our observations reveal a velocity gradient along the western side of the disc which indicates rotation. The 18 cm continuum radiation is resolved into a few unresolved sources, plus more diffuse emission and is broadly consistent with emission originating in a starburst.

scholarly journals The Structure and Velocity Field of A78

1989 ◽  
Vol 131 ◽  
pp. 185-185
Author(s):  
P. Pismis ◽  
M. A. Moreno
Keyword(s):  
Velocity Field ◽  
Planetary Nebula ◽  
Image Intensifier ◽  
Radial Velocities ◽  
Central Hole ◽  
Expansion Velocity ◽  
San Pedro ◽  
Systemic Velocity ◽  
Fabry Perot ◽  
The Face

We present a velocity field of the planetary nebula A78 based on three Fabry Pérot Hα (10A) interferograms taken with a focal reducer attached to the 2.1 m reflector of the Observatorio Astronómico Nacional at San Pedro Mártir, Mexico. We have used a single-stage Varo image intensifier and two different étalons with interorder separations of 283 km s−1 (2 interf.) and 100 km s−1 (1 interf.). The scale of the original photographs is 49 arcsec mm−1. Our data have yielded radial velocities in the Hα line at 110 points on the face of A78; the velocity field is far from being smooth. The rings are wide around the central hole, and a few show definite splittings; from these splittings we have estimated an overall expansion velocity of 27 km s−1. The average systemic velocity is found to be around −3 km s−1.

scholarly journals A Collimated Molecular Jet in W 43A Traced by Water Maser Emission

2003 ◽  
Vol 209 ◽  
pp. 267-268
Author(s):  
Hiroshi Imai ◽  
Tetsuo Sasao ◽  
Kumiko Obara ◽  
Toshihiro Omodaka ◽  
Philip J. Diamond
Keyword(s):  
Planetary Nebula ◽  
Stellar Object ◽  
The Other ◽  
Maser Emission ◽  
Other Hand ◽  
Systemic Velocity ◽  
Short Period ◽  
The Common ◽  
Water Maser

We present VLBA observations of the spatial and velocity distributions of 22 GHz H2O and 1612 MHz OH masers in the OH/IR star W 43A. These masers have the same systemic velocity and are, therefore, likely to be associated with the common stellar object. However, the kinematical structures of them are quite different and independent. Most of the H2O masers are extremely collimated spatially and kinematically. The H2O maser jet also seems to be precessing. On the other hand, the OH masers exhibit clear arc-shaped structures indicating a spherically-expanding shell with weak collimation. The W 43A jet is very likely to be predominantly composed of hot molecules traced by H2O maser emission and formed in the immediate vicinity of an unknown star next to another OH/IR star. Such a “molecular jet” is likely to appear only during the short period before a star forms an elongated planetary nebula.

A Discussion on astronomy in the ultraviolet - Skylark rocket observations of ultraviolet spectra of γ 2 Velorum and ζ Puppis

1975 ◽  
Vol 279 (1289) ◽  
pp. 355-369 ◽  
Keyword(s):  
Wavelength Range ◽  
Spectral Resolution ◽  
High Velocity ◽  
Stellar Atmospheres ◽  
Photographic Film ◽  
Line Of Sight ◽  
Line Profiles ◽  
Interstellar Gas ◽  
Stellar Spectra ◽  
Ultraviolet Spectra

A star-stabilized Skylark rocket was launched from Woomera in June 1973 to record ultraviolet spectra of the bright stars y 2 Velorum and £ Puppis. The instrumentation consisted of three Wadsworth-mounted objective grating spectrographs with a combined wavelength range 90-230 nm. Stellar spectra were recorded on Kodak 101-01 photographic film, the in-flight spectral resolution being approximately 30 pm. Two exposures were obtained on each of the target stars. The y 2 Vel spectrum observations extend from 92 to 230 nm and the £ Pup spectrum from 100 to 230 nm. Analysis of the spectra provides information about the composition and properties of the interstellar gas in the line of sight. The observations also provide useful data on the stellar atmospheres. P Cygni line profiles are observed in the spectra of both stars indicating that high velocity material is being ejected.

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