A Demarcation Criterion for Hydrogen Burning of Millinovae
Millinovae are a new class of transient supersoft X-ray sources with no clear signature of mass ejection. They show similar triangle shapes of V / I band light curves with 1000 times fainter peaks than typical classical novae. Maccarone et al. regarded the prototype millinova, ASASSN-16oh, as a dwar...
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2025-01-01
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| author | Izumi Hachisu Mariko Kato |
| author_facet | Izumi Hachisu Mariko Kato |
| author_sort | Izumi Hachisu |
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| description | Millinovae are a new class of transient supersoft X-ray sources with no clear signature of mass ejection. They show similar triangle shapes of V / I band light curves with 1000 times fainter peaks than typical classical novae. Maccarone et al. regarded the prototype millinova, ASASSN-16oh, as a dwarf nova and interpreted the supersoft X-rays to originate from an accretion belt on a white dwarf (WD). Kato et al. proposed a nova model induced by high-rate mass accretion during a dwarf nova outburst; the X-rays originate from the photosphere of a hydrogen-burning hot WD, whereas the V / I band photons are from the irradiated accretion disk. Because each peak brightness differs largely from millinova to millinova, we suspect that not all millinova candidates host a hydrogen-burning WD. Based on the light-curve analysis of the classical nova KT Eri that has a bright disk, we find that the disk is more than 2 magnitudes brighter when the disk is irradiated by the hydrogen-burning WD than when not irradiated. We present the demarcation criterion for hydrogen burning to be ${I}_{{\rm{q}}}-{I}_{{\rm{\max }}}\gt 2.2$ , where I _q and ${I}_{{\rm{\max }}}$ are the I magnitudes in quiescence and at maximum light, respectively. Among many candidates, this requirement is satisfied with the two millinovae in which soft X-rays were detected. |
| format | Article |
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| institution | DOAJ |
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| language | English |
| publishDate | 2025-01-01 |
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| spelling | doaj-art-2d63c0ed48a6434f8bfdfbeefd80c9db2025-08-20T03:10:24ZengIOP PublishingThe Astrophysical Journal1538-43572025-01-01983214510.3847/1538-4357/adc107A Demarcation Criterion for Hydrogen Burning of MillinovaeIzumi Hachisu0https://orcid.org/0000-0002-0884-7404Mariko Kato1https://orcid.org/0000-0002-8522-8033Department of Earth Science and Astronomy, College of Arts and Sciences, University of Tokyo , 3-8-1 Komaba, Meguro-ku, Tokyo 153-8902, Japan ; izumi.hachisu@outlook.jpDepartment of Astronomy, Keio University , Hiyoshi, Yokohama 223-8521, JapanMillinovae are a new class of transient supersoft X-ray sources with no clear signature of mass ejection. They show similar triangle shapes of V / I band light curves with 1000 times fainter peaks than typical classical novae. Maccarone et al. regarded the prototype millinova, ASASSN-16oh, as a dwarf nova and interpreted the supersoft X-rays to originate from an accretion belt on a white dwarf (WD). Kato et al. proposed a nova model induced by high-rate mass accretion during a dwarf nova outburst; the X-rays originate from the photosphere of a hydrogen-burning hot WD, whereas the V / I band photons are from the irradiated accretion disk. Because each peak brightness differs largely from millinova to millinova, we suspect that not all millinova candidates host a hydrogen-burning WD. Based on the light-curve analysis of the classical nova KT Eri that has a bright disk, we find that the disk is more than 2 magnitudes brighter when the disk is irradiated by the hydrogen-burning WD than when not irradiated. We present the demarcation criterion for hydrogen burning to be ${I}_{{\rm{q}}}-{I}_{{\rm{\max }}}\gt 2.2$ , where I _q and ${I}_{{\rm{\max }}}$ are the I magnitudes in quiescence and at maximum light, respectively. Among many candidates, this requirement is satisfied with the two millinovae in which soft X-rays were detected.https://doi.org/10.3847/1538-4357/adc107Cataclysmic variable starsClassical novaeDwarf novaeNovaeX-ray astronomy |
| spellingShingle | Izumi Hachisu Mariko Kato A Demarcation Criterion for Hydrogen Burning of Millinovae The Astrophysical Journal Cataclysmic variable stars Classical novae Dwarf novae Novae X-ray astronomy |
| title | A Demarcation Criterion for Hydrogen Burning of Millinovae |
| title_full | A Demarcation Criterion for Hydrogen Burning of Millinovae |
| title_fullStr | A Demarcation Criterion for Hydrogen Burning of Millinovae |
| title_full_unstemmed | A Demarcation Criterion for Hydrogen Burning of Millinovae |
| title_short | A Demarcation Criterion for Hydrogen Burning of Millinovae |
| title_sort | demarcation criterion for hydrogen burning of millinovae |
| topic | Cataclysmic variable stars Classical novae Dwarf novae Novae X-ray astronomy |
| url | https://doi.org/10.3847/1538-4357/adc107 |
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