J/AJ/169/140 JHKLM photometry and light curves of V Cyg (Safonov+, 2025)
Disk in the Circumstellar Envelope of Carbon Mira V Cygni.
Safonov B.S., Zheltoukhov S.G., Tatarnikov A.M., Strakhov I.A.,
Shenavrin V.I.
<Astron. J., 169, 140 (2025)>
=2025AJ....169..140S 2025AJ....169..140S
ADC_Keywords: Photometry, infrared; Stars, variable
Keywords: Circumstellar envelopes ; Mira variable stars ;
Infrared spectroscopy ; Speckle interferometry
Abstract:
Asymptotic giant branch (AGB) stars are the primary source of dust and
complex molecules in the interstellar medium. The determination of
outflow parameters is often hindered by the unknown geometry of the
circumstellar environment, creating a demand for high-angular
resolution observations. We use our near-infrared spectra and
photometry of the carbon AGB star V Cyg, along with literature data,
to construct its spectral energy distribution over a wide range of
wavelengths. The dust envelope responsible for the infrared excess was
also resolved in scattered polarized light at angular scales of
50-80mas using differential speckle polarimetry. We present an
interpretation of the thermal and scattered radiation of the dust
using models of a spherical dusty outflow (Mdust=5.3e-7M☉) and
an inclined equatorial density enhancement, either in the form of a
disk (Mdust=7.6e-3M⊕) or a torus (Mdust=5.7e-3M⊕),
which material is concentrated at stellocentric distances less than
25AU. The dust material consists of amorphous carbon and SiC, with 84%
of the dust being amorphous carbon. Dust particle radii range from 5
to 950nm and follow a power law with an exponent of -3.5. Modeling the
envelope allowed us to improve the accuracy of stellar luminosity
estimations: 21,000L☉ and 8300L☉ at maximum and minimum
brightness, respectively. The relation between the disk and the high
water content in the envelope is also discussed.
Description:
JHKLM photometry was obtained between 2019-04-25 and 2022-11-07 using
the single-channel InSb photometer mounted on the 1.25m telescope of
the Crimean Astronomical Station of the Sternberg Astronomical
Institute (SAI) of Lomonosov Moscow State University (MSU) in Ukraine.
The star BS 7924, with magnitudes J=1.00, H=0.91, K=0.89, L=0.78, and
M=0.87, was used as a photometric standard. The precision of estimates
in all bands is better than 0.02mag.
Near-infrared (NIR; 1-2.5um) spectra of V Cyg were obtained on
2020-04-08, 2020-03-03, and 2023-03-29 using the ASTRONIRCAM
instrument, mounted on the Nasmyth-1 platform of the 2.5m telescope at
the Caucasian Mountain Observatory of SAI MSU in Ukraine. Observations
were conducted in the cross-dispersion mode using a 0.9" wide slit.
The typical effective spectral resolution is ∼1100.
We observed V Cyg using the Speckle Polarimeter on 2020-09-21
(JD=2459114). The instrument was mounted on the 2.5m telescope of CMO
SAI MSU in Ukraine. The epoch of observation is ∼50d before the
maximum brightness in the J-band. The observations were conducted at
three bands centered at 550, 625, and 880nm, with half-widths of 50,
50, and 70nm, respectively.
Objects:
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RA (2000) DE Designation(s)
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20 41 18.26 +48 08 28.8 V Cyg = 2MASS J20411826+4808288
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 37 50 JHKLM photometry of V Cyg
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See also:
B/gcvs : General Catalogue of Variable Stars (Samus+, 2007-2017)
I/259 : The Tycho-2 Catalogue (Hog+ 2000)
II/297 : AKARI/IRC mid-IR all-sky Survey (ISAS/JAXA, 2010)
I/337 : Gaia DR1 (Gaia Collaboration, 2016)
I/357 : Gaia DR3 Part 3. Non-single stars (Gaia Collaboration, 2022)
VII/233 : 2MASS All-Sky Extended Source Catalog (XSC) (IPAC/UMass, 2003-2006)
J/A+A/369/178 : Effective temperatures of carbon-rich stars (Bergeat+, 2001)
J/MNRAS/386/313 : IR observations of Mira variables (Whitelock+, 2008)
J/A+A/503/913 : Synthetic spectrophotometry for C-rich giants (Aringer+, 2009)
J/A+A/642/A93 : EP Aqr ALMA and SPHERE observations (Homan+, 2020)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 7 F7.1 d MJD [58598/59892] Modified Julian date, JD-2400000
9- 13 F5.2 mag Jmag [2.06/3.82] Apparent J band magnitude
15- 19 F5.2 mag Hmag [0.71/2.22] Apparent H band magnitude
21- 25 F5.2 mag Kmag [-0.38/0.67] Apparent K band magnitude
27- 31 F5.2 mag Lmag [-1.9/-0.96] Apparent L band magnitude
33- 37 F5.2 mag Mmag [-2.08/-1.08] Apparent M band magnitude
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History:
From electronic version of the journal
(End) Prepared by [AAS], Robin Leichtnam [CDS] 19-Dec-2025