- vsnet-alert - ooruri.kusastro.kyoto-u.ac.jp

[vsnet-alert 26674] Gaia22ayj: outburst from ultrashort period binary?
by Taichi Kato 23 Mar '22

23 Mar '22

Gaia22ayj: outburst from ultrashort period binary? ZTF data recorded time-resolved photometry on 2019 Jan. 10. The data show very clear double-wave modulations with a period of 0.006500(7) d. Using this period, I analyzed the entire ZTF data and found a period of 0.006499102(1) d = 9.4 min. The profile looks like that of a beta Lyr star with the primary and secondary eclipses of 1.5 and 0.7 mag. Although the period could be that of the spin period of the white dwarf, the amplitude is too large and the profile is too stable. The profile very much looks like an eclipsing binary and the period may be the orbital period. The period is, however, surprisingly short. The value is close to that of the direct impact AM CVn-type accretor V407 Vul (0.006590 d). Gaia22ayj showed an outburst (mag 16 in early March and may be still ongoing) and it suggests the presence of an accretion disk. Could it be a pre-AM CVn object? 082526.528 -223212.35 (2000.0) Gaia_DR2_5697000580270393088 plx=0.601(0.381) dismod=11.1 pmra=-4.255(0.538) pmdec=2.477(0.370) G=19.241 BP=19.399 RP=18.345 082526.528 -223212.34 (2000.0) Gaia_EDR3_5697000580270393088 plx=0.430(0.220) dismod=11.8 pmra=-4.238(0.206) pmdec=2.636(0.171) G=19.216 BP=19.570 RP=18.461

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[vsnet-alert 26673] ASASSN-22dl: eclipses
by Taichi Kato 20 Mar '22

20 Mar '22

ASASSN-22dl: eclipses Josch Hambsch and Itoh-san have reported new observations. The object already show eclipses at least since Mar. 18. It may have already entered a phase of ordinary superhumps (now stage A).

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[vsnet-alert 26672] ASASSN-15rs superoutburst
by Taichi Kato 18 Mar '22

18 Mar '22

ASASSN-15rs superoutburst YYYYMMDD(UT) mag observer 20220307.5176 <160c (Yutaka Maeda) 20220308.492 175C (Mitsutaka Hiraga) 20220308.5174 <163c (Yutaka Maeda) 20220309.5193 <153c (Yutaka Maeda) 20220310.5125 <145c (Yutaka Maeda) 20220312.4952 142:cG (Yutaka Maeda) 20220315.5073 <133c (Yutaka Maeda) 20220315.5319 146C (Masayuki Moriyama) 20220316.5009 143cG (Yutaka Maeda) 20220316.5009 143cG (Yutaka Maeda)

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[vsnet-alert 26671] MASTER OT J021216.01+461154.5 possible superoutburst
by Taichi Kato 18 Mar '22

18 Mar '22

MASTER OT J021216.01+461154.5 possible superoutburst Type from ZTF data. Supercycle about 800 d. YYYYMMDD(UT) mag observer 20220306.4731 <153c (Yutaka Maeda) 20220307.469 <174C (Mitsutaka Hiraga) 20220307.4768 <150c (Yutaka Maeda) 20220308.465 <174C (Mitsutaka Hiraga) 20220308.4765 <155c (Yutaka Maeda) 20220309.4784 <152c (Yutaka Maeda) 20220311.4562 <155c (Yutaka Maeda) 20220312.4537 <154c (Yutaka Maeda) 20220315.4640 139cG (Yutaka Maeda) 20220316.4602 138cG (Yutaka Maeda) 20220316.5197 140:C (Masayuki Moriyama)

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[vsnet-alert 26670] Re: ASASSN-22dl: new WZ Sge-type dwarf nova with large-amplitude early superhumps
by Taichi Kato 17 Mar '22

17 Mar '22

Re: ASASSN-22dl: new WZ Sge-type dwarf nova with large-amplitude early superhumps Using the ZTF data, I obtained Min(BJD) = 2458713.27415(12) + 0.05561039(3) d This is a deeply eclipsing WZ Sge-type object whose eclipse minima were below the detection limit of the ZTF observations. Orbital humps before the eclipses were also apparent, suggesting that the mass-transfer rate is not very low. The period of early superhumps (but still from a short baseline) is shorter than the orbital period by 0.13%, typical for a WZ Sge star. Tampo-san and Sebastian, please be careful about in drawing the conclusion. The ZTF data also have one-day aliases.

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[vsnet-alert 26669] Re: ASASSN-22dl: new WZ Sge-type dwarf nova with large-amplitude early superhumps
by Taichi Kato 17 Mar '22

17 Mar '22

Re: ASASSN-22dl: new WZ Sge-type dwarf nova with large-amplitude early superhumps I obtained a period of 0.0561(3) d from Kyoto U. data alone (very good data). The combined set with Itoh-san's data yielded a period of 0.05554(2) d. It looks like that the longer period is the true one.

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[vsnet-alert 26668] ASASSN-22dl: new WZ Sge-type dwarf nova with large-amplitude early superhumps
by 反保雄介 16 Mar '22

16 Mar '22

ASASSN-22dl: new WZ Sge-type dwarf nova with large-amplitude early superhumps Kyoto Univ. team observed ASASSN-22dl on 16th March. Combining with the data from Itoh-san on 15th, we obtained the double-peaked variation with the period of 0.05259(2) or 0.05555(2) d (alias) and the mean amplitude of 0.5 mag. Judging from its period and phase-averaged profile, I conclude that ASASSN-22dl is a new WZ Sge-type dwarf nova with a large amplitude early superhump. Also, the quiescence data of ZTF showed a possible variation with the period of 0.052673(1) d and with the double-peaked profile. Further observations are encouraged! Best, Yusuke 2022年3月16日(水) 8:55 Taichi Kato <tkato(a)kusastro.kyoto-u.ac.jp>: > ASASSN-22dl: superhump or early superhump? > > Itoh-san detected large variations up to 0.8 mag. > There were two maxima in one cycle and the profile > suggest either an early superhump or superhump + eclipse. > The period was around 0.054 d. Further observations > are encouraged. > -- ---------------------------------------------- Kyoto University, Graduate School of Department of Astronomy, PhD student Yusuke TAMPO MAIL: tampo(a)kusastro.kyoto-u.ac.jp ----------------------------------------------

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[vsnet-alert 26667] ASASSN-22dl: superhump or early superhump?
by Taichi Kato 16 Mar '22

16 Mar '22

ASASSN-22dl: superhump or early superhump? Itoh-san detected large variations up to 0.8 mag. There were two maxima in one cycle and the profile suggest either an early superhump or superhump + eclipse. The period was around 0.054 d. Further observations are encouraged.

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[vsnet-alert 26653] ASASSN-19hd rare outburst
by Taichi Kato 15 Mar '22

15 Mar '22

ASASSN-19hd rare outburst SU UMa star? YYYYMMDD(UT) mag observer 20220305.5545 <170c (Yutaka Maeda) 20220306.5578 <154c (Yutaka Maeda) 20220307.5619 <165c (Yutaka Maeda) 20220308.5617 <162c (Yutaka Maeda) 20220309.5636 <160c (Yutaka Maeda) 20220310.5563 146:c (Yutaka Maeda)

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[vsnet-alert 26654] AB Nor likely superoutburst
by Taichi Kato 14 Mar '22

14 Mar '22

AB Nor likely superoutburst YYYYMMDD(UT) mag observer 20220311.3231 13.69C (Masao Funada)

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