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3 results on '"Dufoer, Sjoerd"'

1. ASASSN-19ax: SU UMa-type dwarf nova with a long superhump period and post-superoutburst rebrightenings

Author

Kato, Taichi, Itoh, Hiroshi, Kiyota, Seiichiro, Vanmunster, Tonny, Tordai, Tamas, Tampo, Yusuke, Kojiguchi, Naoto, Shibata, Masaaki, Ito, Junpei, Pickard, Roger D., and Dufoer, Sjoerd

Subjects
Astrophysics - Solar and Stellar Astrophysics, FOS: Physical sciences, Solar and Stellar Astrophysics (astro-ph.SR)
Abstract

We observed ASASSN-19ax during the long outburst in 2021 September-October. The object has been confirmed to be an SU UMa-type dwarf nova with a superhump period of 0.1000-0.1001 d. This object showed two post-superoutburst rebrightenings both in the 2019 and 2021 superoutbursts. These observations have established that ASASSN-19ax belongs to a group of long-period SU UMa-type dwarf novae which show multiple rebrightenings. This phenomenon probably arises from premature quenching of the superoutburst due to the weak 3:1 resonance near the stability border of the resonance, resulting in a considerable amount of disk mass after the superoutburst. We noted that ASASSN-19ax is very similar to QZ Ser, an SU UMa-type dwarf nova with an orbital period of 0.08316 d and an anomalously hot, bright secondary star, in that both objects showed multiple post-superoutburst rebrightenings at least once and that they are bright in quiescence. We expect that the core of the secondary in ASASSN-19ax may be evolved as in QZ Ser., 9 pages, 7 figures, to appear in VSOLJ Variable Star Bulletin

Published
2021

2. Investigating the Low-flux States in Six Intermediate Polars.

Author

Covington, Ava E., Shaw, Aarran W., Mukai, Koji, Littlefield, Colin, Heinke, Craig O., Plotkin, Richard M., Barrett, Doug, Boardman, James, Boyd, David, Brincat, Stephen M., Carstens, Rolf, Collins, Donald F., Cook, Lewis M., Cooney, Walter R., Fernández, David Cejudo, Dufoer, Sjoerd, Dvorak, Shawn, Galdies, Charles, Goff, William, and Hambsch, Franz-Josef

Subjects
LIGHT curves, CATACLYSMIC variable stars, WHITE dwarf stars, ACCRETION (Astrophysics), ACCRETION disks, PHOTOMETRY
Abstract

We present optical photometry of six intermediate polars that exhibit transitions to a low-flux state. For four of these systems, DW Cnc, V515 And, V1223 Sgr, and RX J2133.7+5107, we are able to perform timing analysis in and out of the low states. We find that, for DW Cnc and V515 And, the dominant periodicities in the light curves change as the flux decreases, indicating a change in the sources’ accretion properties as they transition to the low state. For V1223 Sgr, we find that the variability is almost completely quenched at the lowest flux, but we do not find evidence for a changing accretion geometry. For RX J2133.7+5107, the temporal properties do not change in the low state, but we do see a period of enhanced accretion that is coincident with increased variability on the beat frequency, which we do not associate with a change in the accretion mechanisms in the system. [ABSTRACT FROM AUTHOR]

Published
2022
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3. An Asymmetric Eclipse Seen toward the Pre-main-sequence Binary System V928 Tau.

Author

van Dam, Dirk M., Kenworthy, Matthew A., David, Trevor J., Mamajek, Eric E., Hillenbrand, Lynne A., Cody, Ann Marie, Howard, Andrew W., Isaacson, Howard, Ciardi, David R., Rebull, Luisa M., Stauffer, John R., Patel, Rahul, tors, Rodriguez, Joseph E., Pojmański, Grzegorz, Gonzales, Erica J., Schlieder, Joshua E., Hambsch, Franz-Josef, Dufoer, Sjoerd, and Vanmunster, Tonny

Published
2020
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