J/A+A/682/A17 IRAS 20216+4104 spectra (Szymczak+, 2024)
Seven-year periodic variations in the methanol maser line displayed by the
massive protostar IRAS 20216+4104.
Szymczak M., Durjasz M., Goedhart S., Wolak P., Bartkiewicz A.,
Caratti o Garatti A., Kobak A., Massi F.
<Astron. Astrophys. 682, A17 (2024)>
=2024A&A...682A..17S 2024A&A...682A..17S (SIMBAD/NED BibCode)
ADC_Keywords: Infrared sources ; Masers
Keywords: ISM: molecules - radio lines: ISM - individual: IRAS 20216+4104 -
stars: formation - masers
Abstract:
We report the discovery and analysis of a periodic methanol maser in
the massive protostar IRAS 20216+4104.
To obtain the light curve, we used the 6.7GHz methanol maser spectra
collected between 2000-2003 and 2009-2023 with the Hartebeesthoek and
Torun radio telescopes, as well as spectra from the literature
reported prior to 1992.
The velocity-integrated flux density shows sinusoidal-like variations
with a period of 6.9±0.03yr. All but one of the features show
periodic changes with a relative amplitude of 2 up to >89. A slightly
variable feature displays a moderate anti-correlation between the flux
density and the other significantly variable features. The maser
emission appears to follow the continuum emission of the red-shifted
outflow cavity. A maximum emission of 3.4 and 4.6um precedes the
maser peak by 15% of the period and the (infrared) IR light centroids
show time-dependent displacement. The periodic behaviour of the maser
and IR emission is likely due to the eclipsing effect from a wobbling
inner disk.
Description:
The HartRAO data used here were taken as part of a monitoring
programme published in Goedhart et al. (2004MNRAS.355..553G 2004MNRAS.355..553G), spanning
from January 2000 to February 2003 (MJD 51567-52681). The target was
observed on average twice a month with a spectral resolution of
0.112km/s and 3σ sensitivity of 1.2Jy. We obtained data from the
Torun radio telescope between June 2009 and September 2023 (MJD
55006-60208) at a weekly cadence. The data from the initial period
(June 2009 to February 2013) were published in Szymczak et al.
(2018MNRAS.474..219S 2018MNRAS.474..219S, Cat. J/MNRAS/474/219), where the instrument,
observations, and data reduction methods were described in detail. In
short, a spectral resolution was 0.09km/s, a typical 3σ
sensitivity of 0.9Jy and calibration accuracy of 10%.
Objects:
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RA (2000) DE Designation(s)
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20 14 25.88 +41 13 36.9 IRAS 20126+4104 = GAL 078.12+03.64
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
fig1.dat 74 667 Time series of the velocity integrated 6.7GHz
maser flux density in IRAS 20216+4104
fig4.dat 100 4690 Light curves of the main maser features in
IRAS 20216+4104 taken with the Torun telescope
figa1.dat 173 81374 Dynamic spectrum of the 6.7GHz methanol maser
emission of IRAS 20216+4104
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Byte-by-byte Description of file: fig1.dat
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Bytes Format Units Label Explanations
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1- 24 E24.18 d MJD Modified Julian Day
26- 49 E24.18 Jy.km/s Si Integrated flux density at 6.7GHz
51- 74 E24.18 Jy.km/s e_Si Integrated flux density at 6.7GHz error
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Byte-by-byte Description of file: fig4.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 24 E24.18 d MJD Modified Julian Day
26- 49 E24.18 Jy S Flux density
51- 74 E24.18 Jy e_S Flux density error
76-100 E25.18 km/s VLSR LSR velocity
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Byte-by-byte Description of file: figa1.dat
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Bytes Format Units Label Explanations
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3- 5 I3 --- ObsNr [1/667] Epoch number
7- 19 F13.7 d MJD Modified Julian Day
22- 33 F12.7 yr Date Decimal year
36- 47 F12.7 --- Channel Spectral channel
52- 61 F10.7 km/s VLSR LSR velocity
65- 75 F11.7 Jy SI I flux density
81- 89 F9.7 Jy e_SI I flux density error
93-103 F11.7 Jy SV V flux density flux density
109-117 F9.7 Jy e_SV V flux density error
121-131 F11.7 Jy SLHC LHC flux density
137-145 F9.7 Jy e_SLHC LHC flux density error
149-159 F11.7 Jy SRHC RHC flux density
164-173 F10.7 Jy e_SRHC RHC flux density error
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Acknowledgements:
Marian Szymczak, md(at)astro.umk.pl
(End) Patricia Vannier [CDS] 09-Dec-2023