J0328-1219 Photometry Observations, Season #3
by amateur Bruce L. Gary, using a 16" telescope at the Hereford Arizona Observatory (HAO)
Last updated: 2022.09.30, 02 UT

This web page is meant to be an archive of my light curve observations for "observing season #3" (2022 August to 2023 February) of white dwarf J0328 using my HAO backyard observatory 16" Ritchey-Chretien AstroTech telescope with a SBIG XME-10 CCD, g' band filter (link). Most of my web pages are meant for documenting observations and analysis results for myself (it's easier than using a filing cabinet). My web pages can sometimes serve to help with collaborations if I join with others to study the same star. This web page may serve these dual purposes since I'm aware of a group of astronomers (headed by Zachary Vanderbosch) that was engaged in the first and second observing seasons of observations following publication about the variable nature of J0328. My Web Site #2 is located at http://www.brucegary.net/J0328-2/; it includes my observations during the 2nd observing season (2021.11.10 to 2022.02.09).

Latest Waterfall Plot


Yes, I know; most of these dashed-line associations are statistically uncertain. As usual, we need more data. Keep in mind that dips with P = 11.2 hrs will appear at "random" locations on this waterfall plot (or associated with slopes very steeply slanted to the right).

Latest Phase-Fold Light Curves for Date Groups






Only 3 nights before clouds came.




This periodogram shows peaks at 9.939 and 11.64 hrs (0.41411 and 0.48508 day).


This is a 15-night (3100 measurement) phase-folded LC using the A-system period of 9.931 hrs.


This is a 15-night (3100 measurement) phase-folded LC using the B-system period of 11.64 hrs. It is made after subtracting an A-system model and adding 1 to these differences. B-system dips have depths of only ~ 3 %, compared with ~ 10 % for A-system dips.

General Information

RA/DE = 03:28:33.7 -12:19:45, g'-mag = 16.7, white dwarf type DZ, T_eff = 8750 (170) K (Guidry et al., 2020). Observing season is centered on Nov 18 (and extends from about Aug 01 to Mar 05).

List of Internal Links

    Observing session dates  
    Observing session LCs  
    Finder image  
    Physical model suggestion  
    References  
    Related external links  


Observing Session Dates


2022.09.27   Data for this and preceding 14 dates: link
2022.09.26  
2022.09.25  
2022.09.22  

2022.09.18  
2022.09.17  
2022.09.16  
2022.09.15  

2022.09.07  
2022.09.06  
2022.09.05  

2022.09.01  
2022.08.31  
2022.08.30  
2022.08.29  

Observing Session Light Curves


2022.09.27 





2022.09.26 



2022.09.25  



2022.09.22  




2022.09.18 



2022.09.17   Obs'd without filter, which I'll do from now on.





2022.09.16  



2022.09.15  



2022.09.07 

Too many clouds (only 2 hrs without).



2022.09.06  



2022.09.05 






2022.09.01 



2022.08.31 



2022.08.30 



 

2022.08.29 




 
Finder Image



Finder image. FOV = 15 x 10 'arc.
North up, east left.

Physical Model Suggestion

J0328 resembles WD1145 in the following ways: 1) dips are present some of the time, 2) dips exist for weeks to months, 3) the inner-most orbit is the most active in producing dips, and 4) dust clouds are in orbits that can (or must) be close to the WD's tidal radius. J0328 differs from WD1145 in the following respects: 1) during seasons #1 and #2 J0328 dips were present essentially all the time, whereas for WD1145 there are almost always plenty of OOT time per orbit, 2 ) the J0328 dust clouds are in a larger orbit , with P > twice the WD1145 P's. 


Since the WD1145 dust cloud sources (fragments of a planetesimal source) are certainly related in some way to being on the verge of tidal disruption I suggest that the J0628 dust clouds are produced by the same mechanism. I propose that the fragments for both WD1145 and J0328 are being bombarded by a background of rock collisions that become exhausted at the fragment location after a few weeks to months. This replenishment of dust that is continually lost from Keplerian shear and radiation pressure amounts to a steady-state of production and loss, thus accounting for long timescale preservation of dust cloud shape (depth and width) that would not occur in the absence of continual collision bombardment.

When a fragment begins to be bombarded by a swarm of rocky debris it will start with a shape that is narrow and will deepen quickly, while eventually reaching a steady-state level of collisional bombardment. While the rate of rocky bombardment is constant the dip will have a quasi-constant shape (depth and width). As the background level of rocky debris diminishes the dip should broaden and become reduced in depth. These three life-cycle phases can be thought of as "early, "middle" and "late." Accordingly, this observing season's A dip is in a late phase whereas the B dip is in an early phase.

Whereas WD1145's planetesimal source for fragments is a planetary core (with density ~ 7 g/cc), the J0328 planetesimal source for fragments is an asteroid (with density ~ 2 g/cc).

My Collaboration Policy

Please don't ask me to co-author a paper! At my age of 83 I'm entitled to have fun and avoid work. Observing and figuring things out is fun; writing papers is work. My observations are "in the public domain" and are available for use by anyone. If my data is essential to any publication just mention this in the Acknowledgement section.


References

Vanderbosch, Zachary P., Saul Rappaport, Joseph A. Guidry, Bruce L. Gary and 13 others, "Recurring Planetary Debris Transits and Circumstellar Gas around White Dwarf ZTF J0328-1219," MNRAS arXiv

Xu, Siyi, Samuel Lai and Erik Dennihy, 2020, "Infrared Excesses around Bright White Dwarfs from Gaia and unWISE I," arXiv 

Guidry, Joseph A., Zachary P. Vanderbosch, J. J. Hermes, Brad N. Barlow, Isaac D. Lopez, Thomas M. Boudreaux, Kyle A. Corcoran, Bart H. Dunlap, Keaton J. Bell, M. H. Montgomery, Tyler M. Heintz, D. E. Winget, Karen I. Winget, J. W. Kuehne, 2020, "I Spy Transits and Pulsations: Empirical Variability in White Dwarfs Using Gaia and the Zwicky Transient Facility," submitted to ApJ, arXiv

Rappaport, Saul, Roberto
Sanchis-Ojeda, Leslie A. Rogers, Alan Levine & Joshua Winn, 2013, "The Roche Limit for Close-Orbiting Planets: Minimum Density, Composition Constraints and Applications to the 4.2-Hour Planet KOI 1843.03," ApJ L, arXiv 


External Links of Possible Relevance

J0328 Photometry observations by Bruce Gary during observing season #1 (2020/2021)
WD1145 summary of 4 observing seasons
WD1145 for 2020/21 observing season
Resume of webmaster

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This site opened December12, 2021. Nothing on this web page is copyrighted.