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