J/ApJ/925/L22 KMTNet BVI LCs and spectroscopy of KSP-OT-201701a (Lee+, 2022)
Discovery of a short-period and unusually Helium-deficient dwarf nova
KSP-OT-201701a by the KMTNet Supernova Program.
Lee Y., Kim S.C., Moon D.-S., Park H.S., Drout M.R., Ni Y.Qi, Im H.
<Astrophys. J., 925, L22 (2022)>
=2022ApJ...925L..22L 2022ApJ...925L..22L
ADC_Keywords: Novae; Photometry, UBVRI; Spectra, optical
Keywords: Dwarf novae ; Novae
Abstract:
We present the first ever discovery of a short-period and unusually
helium-deficient dwarf nova KSP-OT-201701a by the Korea Microlensing
Telescope Network Supernova Program. The source shows three
superoutbursts, each led by a precursor outburst, and several normal
outbursts in BVI during the span of ∼2.6yr with supercycle and normal
cycle lengths of about 360 and 76 days, respectively. Spectroscopic
observations near the end of a superoutburst reveal the presence of
strong double-peaked HI emission lines together with weak HeI emission
lines. The helium-to-hydrogen intensity ratios measured by
HeIλ5876 and Hα lines are 0.10±0.01 at a quiescent
phase and 0.26±0.04 at an outburst phase, similar to the ratios
found in long- period dwarf novae, while significantly lower than
those in helium cataclysmic variables (He CVs). Its orbital period of
51.91±2.50 minutes, which is estimated based on time-series
spectroscopy, is a bit shorter than the superhump period of
56.52±0.19 minutes, as expected from the gravitational interaction
between the eccentric disk and the secondary star. We measure its mass
ratio to be 0.37-0.21+0.32 using the superhump period excess of
0.089±0.053. The short orbital period, which is under the period
minimum, the unusual helium deficiency, and the large mass ratio
suggest that KSP-OT-201701a is a transition object evolving to an He
CV from a long-period dwarf nova with an evolved secondary star.
Description:
KSP-OT-201701a was discovered by the Korea Microlensing Telescope
Network (KMTNet) Supernova Program (KSP; Moon+ 2016SPIE.9906E..4IM)
during its wide-field monitoring observations of the spiral galaxy
NGC2280 for about 2.6yr between 2016 October and 2019 May. KSP
conducts high-cadence, multicolor (BVI bands) observations, taking
advantage of 24hr continuous sky coverage provided by the three 1.6m
telescopes of the KMTNet in Chile, South Africa, and Australia.
We conducted time-series spectroscopic observations of KSP-OT-201701a
using GMOS on the 8m Gemini South telescope on 2018 February 9. We
obtained four blue (3725-6770Å) and four red (5260-9860Å) GMOS
spectra, each with an exposure time of 400s, during about 1hr.
In addition, we observed the target using LDSS3-C on the 6.5m Magellan
Clay telescope on 2017 April 30 (spectral range 4400-9990Å).
Objects:
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RA (ICRS) DE Designation(s)
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06 39 23.20 -26 37 18.8 KSP-OT-201701a = KSP-OT-201701a
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
fig1.dat 25 2693 KSP-OT-201701a light curves in B, V, and I bands
fig3.dat 22 1381 Stacked Gemini and Magellan spectra of KSP-OT-201701a
fig4.dat 21 8 Radial velocities measured in Hα emission
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See also:
B/cb : Cataclysmic Binaries, LMXBs, and related objects (Ritter+, 2004)
V/113 : Cataclysmic Binaries, LMXBs, and related objects (Ritter+, 2003)
J/MNRAS/460/2526 : Dwarf novae outbursts properties (Otulakowska-Hypka+, 2016)
J/ApJ/881/22 : BVI phot of TypeII SN KSP-SN-2016kf (Afsariardchi+, 2019)
J/ApJ/910/151 : KMTNet BVi photometry of SNIa KSP-OT-201509b (Moon+, 2021)
Byte-by-byte Description of file: fig1.dat
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Bytes Format Units Label Explanations
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1- 12 F12.6 d MJD Modified Julian Date (JD-2400000.5)
14 A1 --- Filt [BVI] Bandpass
16- 20 F5.2 mag omag [14.97/22.1] Magnitude in Filt,
extinction corrected
22- 25 F4.2 mag e_omag [0.01/0.2] Error of omag
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Byte-by-byte Description of file: fig3.dat
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Bytes Format Units Label Explanations
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1- 7 A7 --- Tel Telescope/Instrument used (1)
9- 14 F6.1 0.1nm lambda [3715.5/9990.4] Wavelength in Angstrom
16- 22 F7.4 10-8W/m3 Flux [-0.005/1.2] Flux, 10-15erg/s/cm2/Å
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Note (1): Telescope/Instrument used as follows:
GMOS = GMOS on the 8-m Gemini South telescope on 2018 February 9th
(827 occurrences);
LDSS3-C = LDSS3-C on the 6.5-m Magellan Clay telescope on 2017 April 30th
(554 occurrences).
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Byte-by-byte Description of file: fig4.dat
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Bytes Format Units Label Explanations
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1- 8 F8.6 h Time Hours from MJD=58158.0
10- 15 F6.2 km/s RVel [-68/173] Radial velocity
17- 21 F5.2 km/s e_RVel [23] Error of radial velocity
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 12-Sep-2023