J/ApJ/926/177 SOFIA/FORCAST NIR monitoring of R Aqr (Sankrit+, 2022)
SOFIA/FORCAST monitoring of the dust emission from R Aqr: start of the eclipse.
Sankrit R., Omelian E., Gorti U., Wagner R.M., Goldman S., Whitelock P.A.
<Astrophys. J., 926, 177 (2022)>
=2022ApJ...926..177S 2022ApJ...926..177S
ADC_Keywords: Stars, variable; Photometry, infrared
Keywords: Asymptotic giant branch stars ; Mira variable stars ;
Symbiotic binary stars ; Circumstellar dust
Abstract:
We present mid-infrared (mid-IR) spectra from our continued monitoring
of R Aquarii, the nearest symbiotic Mira, using the Stratospheric
Observatory for Infrared Astronomy (SOFIA). New photometric and
spectroscopic data were obtained with the Faint Object infraRed CAmera
for the SOFIA Telescope in 2018 and 2019 after the system had started
its "eclipse," during which it became two magnitudes fainter in the
visual. The mid-IR flux, in particular the 10µm silicate feature,
has strengthened compared with the previous cycles. Radiative transfer
models for the circumstellar dust emission were calculated for the new
spectra, and recalculated for those previously obtained using more
appropriate values of the near-IR magnitudes to constrain the
properties of the asymptotic giant branch spectra heating the dust.
The modeling shows that the luminosity dependence on pulsation phase
is not affected by the onset of the eclipse, and that the increase in
the mid-IR flux is due to a higher dust density. The models also
confirm our earlier results that micron-size grains are present, and
that no changes in the grain composition are required to explain the
variations in the spectra.
Description:
As part of our continued monitoring of R Aqr in the mid-IR, we
obtained photometric and spectroscopic data using FORCAST on board
SOFIA on 2018 August 24 and 2019 October 16 (all dates are UTC) during
Observing Cycles 6 and 7, respectively. The FORCAST instrument has a
suite of imaging filters and low-dispersion grisms, and covers the
5.4-37.5um wavelength region, except for a gap between about 13.5 and
17.5um.
R Aqr was monitored at near-IR wavelengths between 1980 and 2014 using
the MkII photometer on the 0.75m telescope at the Sutherland site of
the South African Astronomical Observatory. See Section 2.1.
Objects:
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RA (ICRS) DE Designation(s)
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23 43 49.46 -15 17 04.1 R Aquarii = V* R Aqr
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 32 189 Infrared Photometry
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See also:
J/A+AS/146/407 : Symbiotic stars catalogue (Belczynski+, 2000)
J/A+AS/146/437 : IR spectra of oxygen-rich evolved stars (Speck+, 2000)
J/AJ/131/612 : Infrared-optical phase lags in AGB stars (Smith+, 2006)
Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1- 8 F8.2 d JD [2592.5/16975.34] Julian Date; JD-2440000 (1)
10- 14 F5.2 mag Jmag [-0.1/3.5]? Apparent SAAO J band magnitude (2)
16- 20 F5.2 mag Hmag [-1.1/2.01]? Apparent SAAO H band magnitude (2)
22- 26 F5.2 mag Kmag [-1.6/0.9]? Apparent SAAO K band magnitude (2)
28- 32 F5.2 mag Lmag [-2.4/-0.57]? Apparent SAAO L band magnitude (2)
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Note (1): No exact times available for the first 13 observations.
Note (2): These data are on the photometric system described by
Carter (1990MNRAS.242....1C 1990MNRAS.242....1C), which can be converted to the
2MASS system following Carpenter (2001AJ....121.2851C 2001AJ....121.2851C).
Uncertainty is 0.02mag for JHK and 0.05 for L bands.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 03-Nov-2023