J/A+A/700/A194 PN physical and spectr. param. of RRLs (Huertas-Roldan+, 2025)
Deep survey of millimeter radio recombination lines towards the planetary
nebulae IC 418 and NGC 7027.
Huertas-Roldan T., Alcolea J., Garcia-Hernandez D.A., Tafoya D.,
Fonfria J.P., Diaz-Luis J.J., Manchado A., Bujarrabal V., Barzaga R.,
Gomez-Munoz M.A.
<Astron. Astrophys. 700, A194 (2025)>
=2025A&A...700A.194H 2025A&A...700A.194H (SIMBAD/NED BibCode)
ADC_Keywords: Planetary nebulae ; Millimetric/submm sources ; Radio lines
Keywords: catalogs - radio lines: stars - submillimeter: stars -
planetary nebulae: individual: IC 418 -
planetary nebulae: individual: NGC 7027
Abstract:
The circumstellar environments of planetary nebulae (PNe) are
wonderful chemically rich astrophysical laboratories in which the
ionization of atoms and the formation of simple and complex molecules
can be studied. The new generation of high-sensitivity receivers opens
the possibility to carry out deep observations which are needed to
unveil weak atomic and molecular spectra lying in the millimeter (mm)
range. The main goal of this work is to study the emission lines
detected in the spectra of the bright C-rich PNe IC 418 and NGC 7027
and to identify all those emission features associated with radio
recombination lines (RRLs) of light elements. We aim to analyze the
RRLs detected on each source, and to model the sources and derive
their physical parameters. This work allows us to provide the most
complete and updated catalog of RRLs in space. We present the results
of our very deep line survey of IC 418 and NGC 7027 carried out at 2,
3 and 7mm with the IRAM 30m and the Yebes 40m radio telescopes. We
compare these observational data sets with synthetic models produced
with the radiation transfer code Co3RaL. Results. Our observations
towards the target PNe reveal the presence of several H and He i RRLs
at mm wavelengths in the spectra of IC 418 and NGC 7027 and also of He
ii RRLs in the spectrum of NGC 7027. Many of these lines had remained
undetected until now due to their weakness and the lack of
high-sensitivity observations at these frequencies. The data also
confirm the absence of molecular emission towards IC 418, above a
detection level of ∼3mK [Tmb]. Conclusions. These mm observations
represent the most extended RRL line survey of two C-rich PNe carried
out so far, with most of the lines never reported before. These
extremely complete catalogs evidence the importance of
high-sensitivity observations and are expected to be very helpful in
the line identification process in mm observations, in particular for
still unknown or poorly characterized molecular species existing in
the vicinity of ionized environments.
Description:
We present the physical parameters of the radio recombination lines
(RRLs) detected in the planetary nebulae IC 418 and NGC 7027 at 2, 3,
and 7mm. The RRLs were observed with the Yebes 40m and IRAM 30m
telescopes, and the data were analysed using the GILDAS-CLASS
software. The RRLs were fitted with Gaussian profiles, obtaining the
central velocity of the line (km/s), the line width (km/s), the area
(K.km/s), and the peak intensity (K in Tmb scale).
Objects:
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RA (2000) DE Designation(s)
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05 27 28.2 -12 41 50 IC 418 = PN G215.2-24.2
21 07 01.5 +42 14 10 NGC 7027 = PN G084.9-03.4
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tableb1.dat 188 460 Physical parameters of the radio recombination
lines (RRLs) detected in the planetary nebulae
IC 418 and NGC 7027 at 2, 3, and 7mm
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Byte-by-byte Description of file: tableb1.dat
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Bytes Format Units Label Explanations
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1- 17 A17 --- Line Name of the RRL transition
19- 28 F10.3 MHz nutheo Frequency at the center of the line
30- 36 F7.3 s-1 A1 IC 418 Einstein coefficient
38 A1 --- Status1 IC 418 Status of the line (1)
40- 45 F6.3 km/s v01 ? IC 418 Central velocity of the line
47- 51 F5.3 km/s e_v01 ? IC 418 Central velocity of the line error
52 A1 --- l_Tmb1 Limit flag on Tmb1
53- 59 F7.3 mK Tmb1 ? IC 418 Main beam temperature of the peak
61- 66 F6.3 mK e_Tmb1 ? IC 418 Main beam temperature of the peak
67 A1 --- l_Area1 Limit flag on Area1
68- 73 F6.4 K.km/s Area1 ? IC 418 Area under the line
75- 80 F6.4 K.km/s e_Area1 ? IC 418 Area under the line
83- 88 F6.3 km/s FWHM1 ? IC 418 Full width at half maximum (2)
90- 95 F6.3 km/s e_FWHM1 ? IC 418 Full width at half maximum (2)
97-112 A16 --- Comm1 IC 418 Comments (3)
114 A1 --- Status2 NGC 7027 Status of the line (1)
116-121 F6.3 km/s v02 ? NGC 7027 Central velocity of the line
123-127 F5.3 km/s e_v02 ? NGC 7027 Central velocity of the line
128 A1 --- l_Tmb2 Limit flag on Tmb2
129-134 F6.2 mK Tmb2 ? NGC 7027 Main beam temperature of the peak
136-140 F5.2 mK e_Tmb2 ? NGC 7027 Main beam temperature of the peak
142 A1 --- l_Area2 Limit flag on Area2
143-148 F6.3 K/km/s Area2 ? NGC 7027 Area under the line
150-154 F5.3 K/km/s e_Area2 ? NGC 7027 Area under the line
157-162 F6.3 km/s FWHM2 ? NGC 7027 Full width at half maximum (2)
164-169 F6.3 km/s e_FWHM2 ? NGC 7027 Full width at half maximum (2)
171-188 A18 --- Comm2 NGC 7027 Comments (3)
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Note (1): Status as follows:
D = detected
T = tentative
L = detection limits
Note (2): Values of lines below the detection limits are estimated using the
average of the corresponding Δn set of lines. FWHM values of HeII in
IC 418 have been estimated calculating the average of the FWHM H lines with
the same Δn in IC 418 and NGC 7027 and then calculating the ratio of
the average in NGC 7027 and in IC 418.
Note (3): Cpmments:
S = single line
B = line blended with another RRL
C = line contaminated by known molecular emission or
an unidentified feature (UF)
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Acknowledgements:
Teresa Huertas-Roldan, thuertas(at)iac.es
(End) Patricia Vannier [CDS] 02-Jul-2025