J/A+A/649/A164 Protoplanetary nebulae and young PN CO spectra (Lorenzo+, 2021)
Fast outflows in protoplanetary nebulae and young planetary nebulae observed
by Herschel/HIFI.
Lorenzo, M., Teyssier D., Bujarrabal V., Garcia-Lario P., Alcolea J.,
Verdugo E., Marston A.
<Astron. Astrophys. 649, A164 (2021)>
=2021A&A...649A.164L 2021A&A...649A.164L (SIMBAD/NED BibCode)
ADC_Keywords: Planetary nebulae ; Carbon monoxide ; Spectra, radio
Keywords: stars: AGB, post-AGB - circumstellar matter - stars: mass-loss -
planetary nebulae: general
Abstract:
Fast outflows and their interaction with slow shells (generally known
as the fossil circumstellar envelope of asymptotic giant branch stars)
play an important role in the structure and kinematics of
protoplanetary and planetary nebulae (pPNe, PNe). To properly study
their effects within these objects, we also need to observe the
intermediate-temperature gas, which is only detectable in the
far-infrared (FIR) and submillimetre (submm) transitions.
We study the physical conditions of the outflows presented in a number
of pPNe and PNe, with a focus on their temperature and excitation
states.
We carried out Herschel/HIFI observations in the submm lines of 12CO
in nine pPNe and nine PNe and complemented them with low-J CO spectra
obtained with the IRAM 30m telescope and taken from the literature.
The spectral resolution of HIFI allows us to identify and measure the
different nebular components in the line profiles. The comparison with
large velocity gradient (LVG) model predictions was used to estimate
the physical conditions of the warm gas in the nebulae, such as
excitation conditions, temperature, and density.
We found high kinetic temperatures for the fast winds of pPNe,
typically reaching between 75K and 200K. In contrast, the
high-velocity gas in the sampled PNe is colder, with characteristic
temperatures between 25K and 75K, and it is found in a lower
excitation state. We interpret this correlation of the kinetic
temperature and excitation state of fast outflows with the amount of
time elapsed since their acceleration (probably driven by shocks) as a
consequence of the cooling that occurred during the pPN phase.
Description:
We present observations of intermediate-excitation CO lines in a
sample of 18 nebulae carried out with Herschel/HIFI. These
observations have been obtained as part of the guaranteed-time project
SUbmilimetre Catalogue of Circumstellar Envelopes of StarS (SUCCESS),
a submm/FIR CO survey of a large sample of AGB and post-AGBstars. In
particular, this programme obtained observations of the 12CO J=5-4
and J=9-8 lines in 18 post-AGB stars. Of this sample of nebulae, 3
were also observed in the 12CO J=14-13 line and 5 were followed up
in 12CO J=2-1 and J=1-0 lines using the IRAM 30m telescope.
The data are provided as FITS files containing the spectra for each of
the relevant CO transition. The FITS files contain an array of the
antenna temperature in the Tmb scale. The velocity scale can be built
from the information in the header:
- CRPIX1 gives the value of the reference channel
- VELO-LSR gives the value of the LSR velocity at that reference channel
- DELTAV provides the velocity resolution of each channel
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
sources.dat 41 18 List of studied sources
list.dat 165 60 List of fits spectra
fits/* . 60 Individual fits spectra
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Byte-by-byte Description of file: sources.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 15 A15 --- Name Star name
17- 18 I2 h RAh Right ascension (J2000)
20- 21 I2 min RAm Right ascension (J2000)
23- 28 F6.3 s RAs Right ascension (J2000)
30 A1 --- DE- Declination sign (J2000)
31- 32 I2 deg DEd Declination (J2000)
34- 35 I2 arcmin DEm Declination (J2000)
37- 41 F5.2 arcsec DEs Declination (J2000)
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Byte-by-byte Description of file: list.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 15 A15 --- Name Star name
17- 25 F9.5 deg RAdeg Right Ascension of center (J2000)
26- 34 F9.5 deg DEdeg Declination of center (J2000)
36- 40 I5 --- Nx Number of pixels along X-axis
42- 64 A23 "datime" Obs.date Observation date
66- 77 E12.7 Hz BFreq Lower value of frequency interval
79- 89 E11.6 Hz bFreq Upper value of frequency interval
91-101 E11.6 Hz dFreq Frequency resolution
103-104 I2 Kibyte size Size of FITS file
106-129 A24 --- FileName Name of FITS file, in subdirectory fits
132-165 A34 --- Title Title of the FITS file
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Acknowledgements:
Marta Lorenzo, mlorenzo(at)cab.inta-csic.es
(End) Patricia Vannier [CDS] 14-Apr-2021