An upper limit to hydrogen ionization rates from radio recombination-line observations toward 3C123

1984 ◽  
Vol 89 ◽  
pp. 668 ◽  
Author(s):  
H. E. Payne ◽  
E. E. Salpeter ◽  
Y. Terzian
Keyword(s):  
Recombination Line ◽  
Upper Limit ◽  
Radio Recombination Line ◽  
Hydrogen Ionization ◽  
Ionization Rates

Radio recombination line observations towards Spitzer infrared bubbles with the TianMa radio telescope

2019 ◽  
Vol 489 (4) ◽  
pp. 4862-4874
Author(s):  
L G Hou ◽  
X Y Gao
Keyword(s):  
Radio Telescope ◽  
Detection Rate ◽  
Milky Way ◽  
Absorption Method ◽  
Recombination Line ◽  
Ionized Gas ◽  
Radio Recombination Line ◽  
Warm Ionized Medium

ABSTRACT Many of the Spitzer infrared bubbles identified by the Milky Way Project (MWP) are suggested to be $\rm{H \small {II}} $ regions in nature. More than 70 per cent of the ∼5000 known bubbles do not have radio recombination line (RRL) observations, hence have not been confirmed as $\rm{H \small {II}} $ regions. A systematic RRL survey should be helpful to identify the nature of the bubbles. With the Shanghai TianMa 65-m radio telescope, we searched for RRLs towards 216 selected Spitzer bubbles by simultaneously observing 19 RRLs in the C band (4–8 GHz). RRLs are detected in the directions of 75 of the 216 targets. 31 of the 75 RRL sources are classified as new detections, which are possibly from new $\rm{H \small {II}} $ regions or diffuse warm ionized medium; 36 of them are probably from the outskirts of nearby bright $\rm{H \small {II}} $ regions, rather than bubble-encircled ionized gas; and the detected RRLs towards 8 bubbles are identified from known $\rm{H \small {II}} $ regions. For 58 of the 75 RRL sources, we obtained their distances after resolving the kinematic distance ambiguity by combining the results of the H2CO absorption method, the $\rm{H \small {I}} $ emission/absorption method, and the $\rm{H \small {I}} $ self-absorption method. The low detection rate of new $\rm{H \small {II}} $ regions implies that a number of MWP bubbles in the DR1 catalogue are too faint if they are $\rm{H \small {II}} $ regions.

Very Large Array H92α and H53α Radio Recombination Line Observations of M82

2004 ◽  
Vol 616 (2) ◽  
pp. 783-803 ◽  
Author(s):  
C. A. Rodriguez‐Rico ◽  
F. Viallefond ◽  
J.‐H. Zhao ◽  
W. M. Goss ◽  
K. R. Anantharamaiah
Keyword(s):  
Large Array ◽  
Recombination Line ◽  
Very Large Array ◽  
Radio Recombination Line

Erratum: “VLA H53α Radio Recombination Line Observations of the Ultraluminous Infrared Galaxy Arp 220” (ApJ, 633, 198 [2005])

2007 ◽  
Vol 668 (1) ◽  
pp. 625-625 ◽  
Author(s):  
C. A. Rodriguez‐Rico ◽  
W. M. Goss ◽  
F. Viallefond ◽  
J.‐H. Zhao ◽  
Y. Gomez ◽  
...  
Keyword(s):  
Recombination Line ◽  
Infrared Galaxy ◽  
Radio Recombination Line ◽  
Ultraluminous Infrared Galaxy

Interpretation of anomalous helium abundance derived from radio recombination line observations of nebulae

1998 ◽  
Vol 15 (1-4) ◽  
pp. 281-289 ◽  
Author(s):  
D. Ershov ◽  
S. A. Gulyaev ◽  
A. Ivanchik ◽  
D. A. Varshalovich ◽  
A. Tsivilev
Keyword(s):  
Helium Abundance ◽  
Recombination Line ◽  
Radio Recombination Line

scholarly journals Radio recombination line observations at 1.0 – 1.5GHz with FAST

2021 ◽  
Vol 21 (8) ◽  
pp. 209
Author(s):  
Chuan-Peng Zhang ◽  
Jin-Long Xu ◽  
Guang-Xing Li ◽  
Li-Gang Hou ◽  
Nai-Ping Yu ◽  
...  
Keyword(s):  
Recombination Line ◽  
Radio Recombination Line

scholarly journals A Search for Radio Recombination Lines of Positronium Near the Galactic Center

1989 ◽  
Vol 136 ◽  
pp. 607-616 ◽  
Author(s):  
K. R. Anantharamaiah ◽  
V. Radhakrishnan ◽  
D. Morris ◽  
M. Vivekanand ◽  
D. Downes ◽  
...  
Keyword(s):  
Production Rate ◽  
Galactic Center ◽  
Absorption Feature ◽  
Recombination Line ◽  
Radio Recombination Lines ◽  
Upper Limit ◽  
Positron Production

Several attempts were made to detect the possible radio recombination lines of positronium near the galactic center. An absorption feature seen at λ6cm, in the D-configuration of the VLA was not confirmed by subsequent observations at λ6cm and λ20cm using the B and C configurations of the VLA. An observation at λ3mm using the IRAM 30m telescope also did not detect any line. On the basis of one recombination line photon for every positron (McClintock 1984), our non-detections imply an upper limit to the positron production rate of < 3.1 × 1043 s−1, within about 2″ of the galactic center.

scholarly journals Substructures in the Keplerian disc around the O-type (proto-)star G17.64+0.16

2019 ◽  
Vol 627 ◽  
pp. L6 ◽  
Author(s):  
L. T. Maud ◽  
R. Cesaroni ◽  
M. S. N. Kumar ◽  
V. M. Rivilla ◽  
A. Ginsburg ◽  
...  
Keyword(s):  
Angular Resolution ◽  
Dust Emission ◽  
Recombination Line ◽  
Rotating Disc ◽  
Molecular Line ◽  
Vibrationally Excited ◽  
The North ◽  
Radio Recombination Line ◽  
Massive Forming ◽  
North And South

We present the highest angular resolution (∼20 × 15 mas–44 × 33 au) Atacama Large Millimeter/sub-millimeter Array (ALMA) observations that are currently possible of the proto-O-star G17.64+0.16 in Band 6. The Cycle 5 observations with baselines out to 16 km probe scales < 50 au and reveal the rotating disc around G17.64+0.16, a massive forming O-type star. The disc has a ring-like enhancement in the dust emission that is especially visible as arc structures to the north and south. The Keplerian kinematics are most prominently seen in the vibrationally excited water line, H2O 55, 0−64, 3 ν2 = 1 (Eu = 3461.9 K). The mass of the central source found by modelling the Keplerian rotation is consistent with 45 ± 10 M⊙. The H30α (231.9 GHz) radio-recombination line and the SiO (5-4) molecular line were detected at up to the ∼10σ level. The estimated disc mass is 0.6 − 2.6 M⊙ under the optically thin assumption. Analysis of the Toomre Q parameter in the optically thin regime indicates that the disc stability is highly dependent on temperature. The disc currently appears stable for temperatures > 150 K; this does not preclude that the substructures formed earlier through disc fragmentation.

scholarly journals Response of the interplanetary hydrogen population to global changes of solar activity: a quantitative analysis based on SOHO/SWAN and SOHO/LASCO-C2 data comparison.

2021 ◽  
Author(s):  
Dimitra Koutroumpa ◽  
Eric Quémerais ◽  
Lucile Conan ◽  
Philippe Lamy ◽  
Stéphane Ferron ◽  
...  
Keyword(s):  
Interplanetary Space ◽  
Time Lag ◽  
Three Dimensional ◽  
Direct Consequence ◽  
Cycle Phase ◽  
Global Changes ◽  
Hydrogen Atoms ◽  
Hydrogen Ionization ◽  
Coronal Electron ◽  
Ionization Rates

&lt;p&gt;For more than two decades the SOHO/SWAN instrument has been monitoring the full-sky hydrogen backscattered Lyman-&amp;#945; emission, and the derived three-dimensional solar wind proton flux. We present a comparison of the time series of the latitude-integrated hydrogen ionization rates (&amp;#946;) derived from the inversion of the SWAN full-sky maps with the integrated coronal electron density derived from the inversion of SOHO/LASCO-C2 white light images. The analysis shows a variable time lag of the SWAN &amp;#946; of a few Carrington rotations, correlated with the solar cycle phase (larger delay during solar maxima compared to minima). This is a direct consequence of the variation of the size of the hydrogen ionization cavity and the time it takes for hydrogen atoms to propagate in the inner heliosphere. This effect should be taken into account in studies of the interstellar neutral populations in interplanetary space.&lt;/p&gt;

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