J/A+A/667/A7 BVRI photometry of nova V5856 Sgr (Munari+, 2022)
Persistent nuclear burning in Nova Sgr 2016 N.4 (= V5856 Sgr = ASASSN-16ma)
six years past its outburst.
Munari U., Masetti N., Walter F.M., Williams R.E., Hambsch F.-J., Frigo A.,
Valisa P.
<Astron. Astrophys. 667, A7 (2022)>
=2022A&A...667A...7M 2022A&A...667A...7M (SIMBAD/NED BibCode)
ADC_Keywords: Novae ; Photometry, UBVRI ; Spectra, optical
Keywords: novae - cataclysmic variables - stars: winds, outflows
Abstract:
We report about the fast Nova Sgr 2016 N.4 being surprisingly trapped
in a long-lasting and bright plateau (Delta(I)≥10mag above
quiescence), six years past the nova eruption. Very few other novae
experience a similar occurring. We have carried out an intensive
observing campaign collecting daily BVRI photometry, monthly
high-resolution optical spectroscopy, and observed the nova in
ultraviolet and X-rays with Swift at five distinct epochs. The
bolometric luminosity radiated during the plateau is
L(bol)∼4200L☉ (scaled to the distance of the Galactic Bulge),
corresponding to stable nuclear burning on a 0.6M☉ white dwarf.
A stable wind is blown-off at FWZI∼1600km/s, with episodic
reinforcement of a faster FWZI∼3400km/s mass-loss, probably oriented
along the polar directions. The collision of such winds could power
the emission detected in X-rays. The burning shell has an outer radius
of ∼25R☉ at which the effective temperature is ∼7600K, values
similar to those of a F0 II/Ib bright giant. The Delta(m)<1mag
variability displayed during the plateau is best described as chaotic,
with the irregular appearance of quasi-periodic oscillations with a
15-17 days periodicity. A limited amount of dust (∼3x10-11M☉)
continuously condense at T(dust)∼1200K in the outflowing wind,
radiating L(dust)∼52L☉.
Description:
Optical photometry of V5856 Sgr was obtained simultaneously in the
BVRI bands during 108 nights in 2021 and 111 nights in 2022, with the
same robotic 40 cm telescope (located in San Pedro de Atacama, Chile)
and the same observing procedures adopted by Munari et al.
(2017MNRAS.469.4341M 2017MNRAS.469.4341M, Cat. J/MNRAS/469/4341) to cover the main
outburst, in particular (i) the same local photometric sequence around
V5856 Sgr was used to solve the color equations for each observing
night and accurately place the observations on the Landolt
(2009AJ....137.4186L 2009AJ....137.4186L, Cat. J/AJ/137/4186) photometric system, and (ii)
photometry was carried out in PSF-fitting mode on the central server
of ANS Collaboration in Asiago.
Optical spectra of V5856 Sgr were recorded from Italy and from Chile.
From Italy, low-resolution spectroscopy of V5856 Sgr was obtained with
the Asiago 1.22 m telescope equipped with a Boller and Chivens (B&C)
spectrograph. The CCD camera is an ANDOR iDus DU440A with a
back-illuminated E2V 42-10 sensor, 2048x512 array of 13.5um pixels.
The long-slit spectra were recorded with a 300ln/mm grating blazed at
5000Å, and covered the wavelength range from 3300 to 8000Å at
2.31Å/pix.
We also observed V5856 Sgr from Chile, where it transits nearly
overhead, using the CHIRON fiber-fed bench-mounted Echelle fed by the
CTIO 1.5m telescope operated by SMARTS. We used CHIRON in "fiber"
mode with 4x4 on-chip binning yielding a resolution
λ/δλ~=27800.
Objects:
----------------------------------------------------
RA (2000) DE Designation(s)
----------------------------------------------------
18 20 52.25 -28 22 12.1 V5856 Sgr = ASASSN -16ma
----------------------------------------------------
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 72 219 BVRI photometry of nova V5856 Sgr
collected in 2021 and 2022
spectrum.dat 24 2053 Spectrum (fig. 2)
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Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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2- 8 F7.3 d HJD Heliocentric Julian date (HJD-2459000)
10- 23 A14 "date" Date Date (UT) of the observation (YYYY-MM-DD.ddd)
25- 30 F6.3 mag Vmag V magnitude
32- 36 F5.3 mag e_Vmag Error on Vmag
38- 42 F5.3 mag B-V ? B-V color
44- 48 F5.3 mag e_B-V ? Error on B-V color
50- 54 F5.3 mag V-R ? V-R color
56- 60 F5.3 mag e_V-R ? Error on V-R color
62- 66 F5.3 mag R-I ? R-I color
68- 72 F5.3 mag e_R-I ? Error on R-I color
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Byte-by-byte Description of file: spectrum.dat
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Bytes Format Units Label Explanations
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2- 10 F9.4 0.1nm lambda Heliocentric wavelength
12- 24 E13.8 10mW/m2/nm Flux Flux (in erg/cm2/s/Å
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Acknowledgements:
Ulisse Munari, ulisse.munari(at)inaf.it
(End) Patricia Vannier [CDS] 04-Aug-2022