On Variation Mechanisms in Recurrent Nova IM Normae
Abstract
:1. Introduction
2. Reflection Effect Waveform Conceptually
3. Alternating Eclipse Type Interpretation (Resolution I)
Parameter Estimation for Resolution I
4. Case of Eclipses with Strong Tidal Variation in Disk and Star 2 (Resolution II)
5. Final Comments on the Proposed Resolutions
- Resolution I: The orbit period is doubled from to . The disk and star 2 temperatures are set nearly equal. Figure 1’s left panel illustrates the width mismatch if P= =, in agreement with WW’s comments. The right panel appears to show primary and secondary eclipses of slightly different depth and shape and doubled width when displayed for 3 nights to help in visual averaging.
- Resolution II: The period is . Widening of the computed eclipse is accomplished by having a disk with nearly the maximum equatorial dimensions ( vs. in the positive x-coordinate, where a is the orbital semi-major axis length). Apparent further widening is due to phase-dependent tidal variations of disk and star 2, with consequent difficulty in judging eclipse limits.
Funding
Data Availability Statement
Acknowledgments
Conflicts of Interest
1 | Acronym MLR means mass, luminosity, and radius. |
2 | See left panel of Figure 1 and caption. |
3 | Hereafter called star 2, with star 1 being the white dwarf in the center of the disk. |
4 | An example from the recurrent novae is U Scorpii, where a deep primary eclipse is accompanied by a shallow secondary eclipse of to that sometimes disappears Schaefer, et al. [8]. |
5 | ‘Better covered’ meaning that at least some part of the very bottom was observed. |
6 | Limiting lobe size follows from the combined influence of gravitation and rotation. |
7 | The third light for WW’s observations is (almost certainly) the fading nova shell, although some contribution from stars cannot be excluded. |
8 | Eclipse width is set by the sum of the component radii as fractions of component separation (Rdisk/a + R2/a), and by the orbital inclination. The central problem for IM Nor has been that eclipse width has seemed “impossibly wide”, so none of these three parameters can be small. Each must contribute substantially to eclipse width–neither Rdisk/a nor R2/a can “do it all by itself”. Otherwise explanation of the large eclipse width indeed becomes impossible. Note that the requirement is not ‘almost same size’ but ‘same order of size’. |
9 | See Section 2.4 in Wilson [2] for ideas on the main cause of the transients. |
10 | Reflection is noticeable at about 0.02 magnitude semi-amplitude in Honeycutt’s pre-eruption light curve shown in Wilson [2]. |
11 | Logically all local effective gravity vectors must point toward the disk’s interior to be part of the disk. |
References
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a () | (assumed) | |
mass ratio of stars (from stepped trials) | ||
disk/(white dwarf) mass ratio (from trials) | ||
(days) | twice that from WW | |
star 1 rotation parameter (from trials) | ||
star 2 rotation parameter (synchronous) | ||
(K) | star 1 temperature (white dwarf) | |
3687 | temperature of outermost disk | |
star 1 mean radius (white dwarf) | ||
star 2 mean radius | ||
(g/cm) | outer disk density | |
disk semi-thickness (by-product of solution) | ||
2,452,696.62790 | superior conjunction time (white dwarf or disk) | |
i | orbital inclination | |
outer disk coordinate, line of star centers | ||
(K) | star 2 temperature | |
star luminosity ratio (V band assumed) | ||
relative V band third light (phase 0.25) |
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Wilson, R.E. On Variation Mechanisms in Recurrent Nova IM Normae. Galaxies 2022, 10, 96. https://doi.org/10.3390/galaxies10050096
Wilson RE. On Variation Mechanisms in Recurrent Nova IM Normae. Galaxies. 2022; 10(5):96. https://doi.org/10.3390/galaxies10050096
Chicago/Turabian StyleWilson, R. E. 2022. "On Variation Mechanisms in Recurrent Nova IM Normae" Galaxies 10, no. 5: 96. https://doi.org/10.3390/galaxies10050096