December 2022 - vsnet-campaign-polar - ooruri.kusastro.kyoto-u.ac.jp

[vsnet-campaign-polar 150]EF Eri: dips
by Taichi Kato 26 Dec '22

26 Dec '22

EF Eri: dips Observations by Kiyota-san and Itoh-san clearly shows short-duration dips such as at 2022 Dec. 25.618 (UT). These dips were not seen in every orbit but were present almost on every night. The durations were 2-3 min and were 0.8-mag deep. Ingress was slower and egress was sometimes sudden (within 30s).

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[vsnet-campaign-polar 149]Re: EF Eri profile
by Taichi Kato 25 Dec '22

25 Dec '22

Re: EF Eri profile Berto Monard has provided observations on 2006 Mar. 11 (one of high states in the 2000s). The orbital profile was similar to the current one (two maxima per period). It was not always the case in the past. See e.g.: https://ui.adsabs.harvard.edu/abs/1987A%26A...181L..15L/abstract

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[vsnet-campaign-polar 148]EF Eri profile
by Taichi Kato 24 Dec '22

24 Dec '22

EF Eri profile Kyoto U. team, Kiyota-san, Itoh-san, Peter Starr and Josch Hambsch have reported observation. The object shows very clear two peaks (full amplitude 0.7 mag) in one orbital period. The period 0.056269(3) d is in very good agreement with the published one. There is also a dip (somewhat variable), which may be an eclipse of/by the accretion column.

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[vsnet-campaign-polar 147]ASAS-SN light curve of EF Eri
by Taichi Kato 21 Dec '22

21 Dec '22

ASAS-SN light curve of EF Eri First high state since the start of ASAS-SN. https://asas-sn.osu.edu/sky-patrol/coordinate/97767859-7bac-4e8d-bdda-ded38…

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[vsnet-campaign-polar 146]EF Eri short-term variations
by Taichi Kato 20 Dec '22

20 Dec '22

EF Eri short-term variations Kyoto U. team obtained high time-resolution observations. The object showed QPO-like variations with time scales of about 5 min. They could arise from instabilities in the accretion column. Itoh-san and Kiyota-san also reported observations showing large modulations.

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[vsnet-campaign-polar 145]Re: EF Eri (polar) still bright
by Taichi Kato 19 Dec '22

19 Dec '22

Re: EF Eri (polar) still bright Peter Starr reported time-resolved observations. Variations up to 0.8 mag were present.

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[vsnet-campaign-polar 144]EF Eri (polar) still bright
by Taichi Kato 19 Dec '22

19 Dec '22

EF Eri (polar) still bright Large-amplitude variations were suggested from observations by Josch Hambsch. The time resolution was not enough. Observations with higher time resolution are recommended. YYYYMMDD(UT) mag observer 20221123.5642 <162C (Masayuki Moriyama) 20221216.624 148 (Rod Stubbings) 20221216.651 147 (Rod Stubbings) 20221216.658 147 (Rod Stubbings) 20221217.483 146 (Rod Stubbings) 20221218.076 14.26C (Gary Poyner) 20221218.0759 14.20C (Masao Funada) 20221218.878 14.11C (Gary Poyner) 20221218.8778 13.94C (Masao Funada)

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[vsnet-campaign-polar 143]Re: EF Eri in active state!
by Taichi Kato 16 Dec '22

16 Dec '22

> The polar EF Eri is in an active state. > > ERIEF 221216.624 148 > ERIEF 221216.651 147 > ERIEF 221216.659 147 This is rare and very important. This polar has a brown-dwarf secondary and has a low mass-transfer rate.

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[vsnet-campaign-polar 142]Re: DDE 35: more likely a polar
by Taichi Kato 09 Dec '22

09 Dec '22

Re: DDE 35: more likely a polar E. Pavlenko has advised that this object is too blue for a polar. The data by Crimean Astrophys. Obs. team in 2020 showed flickering, but no indication of stable superhumps nor orbital variation. Although a period of 0.20976(3) d was suspected from CrAO observations (by my analysis), this period was not detected in the ZTF data. This object indeed looks like a CV with high/low states, but is certainly neither an SU UMa nor a polar. This object is currently in high state and would be an easy target for spectroscopy to determine the orbital period.

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[vsnet-campaign-polar 141]DDE 35: more likely a polar
by Taichi Kato 03 Dec '22

03 Dec '22

DDE 35: more likely a polar This object was classified as an SU UMa star based on superhump detection (vsnet-alert 24074). These humps, however, were seen only on two nights (2020 Mar. 16 and 18) and no humps were apparent on Mar. 19. The ZTF data show distinct high and low states unlike an SU UMa star (currently in bright state starting from late 2021). The magnitude (around 16) in 2020 Mar. was too faint (M_V=+6.6) for a superoutburst. The behavior suggests that the object is likely a polar. I have not been able to detect an orbital period in the ZTF data.

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