The Long and Short of Transiting Debris Around White Dwarfs

Conference presentation, 20 min. September 2024: Celebrating 21 years of Astronomy at Warwick, Coventry, UK.

Transcript

1. The Long and Short of Transiting Debris Around White Dwarfs J.J. Hermes + Joseph Guidry (BU) Zach Vanderbosch (Caltech) Jay Farihi (UCL) Tom Marsh (Warwick) & many others Mark Garlick
2. Gänsicke, Aungwerojwit, Marsh, et al. 2016 >50% WD1145+017, 1st Transiting WD, Found in K2 Campaign 1 TNT/ULTRASPEC Discovered by Vanderburg, Johnson, Rappaport et al. 2015 • Transits recur every ~4.5 hr (near WD tidal disruption radius) • There are many extended, changing features in the transits minimum transits > 3 min, model is 5.4 RE (4x WD radius)
3. ZTFJ0139+5245, 2nd Transiting WD, Part of DAV Search Vanderbosch, Hermes, Dennihy et al. 2020 • Transits recur every ~107 d (debris likely at high eccentricity) • This is a pulsating WD part of ZTF search within 200pc for new DAV; had one ZTF alert
4. ZTF+Gaia Variability Discovered 5 New Transiting WDs Guidry, Vanderbosch, Hermes, et al. 2021 • Selecting the objects with the largest photometric variability at a given G mag nets many pulsating white dwarfs, and transits
5. WD1054-226: Relentless and complex transits, 25.02 hr Farihi, Hermes, Marsh et al. 2022 g+r
6. WD1054-226: Relentless and complex transits, 25.02 hr Farihi, Hermes, Marsh et al. 2022
7. WD1054-226: Relentless and complex transits, 25.02 hr Farihi, Hermes, Marsh et al. 2022 • Drifting fragments at 25.5 hr
8. WD1054-226: Relentless and complex transits, 25.02 hr Farihi, Hermes, Marsh et al. 2022 • ULTRACAM shows the transits have no color dependence (totally grey) • Spectroscopy shows no circumstellar gas
9. WD1054-226: Relentless and complex transits, 25.02 hr Farihi, Hermes, Marsh et al. 2022 23 min
10. WD1054-226: Relentless and complex transits, 25.02 hr Farihi, Hermes, Marsh et al. 2022 • 65th harmonic of Porb is exceptionally strong
11. WD1054-226: Relentless and complex transits, 25.02 hr Farihi, Hermes, Marsh et al. 2022 • 65th harmonic of Porb is exceptionally strong 9/1/21, 03:48 The only tentative [physical explanation] I have come up with is that there is an unseen object on an orbit that intersects the ~25 hour orbit but with a period that differs from it by 23 minutes. As this object (and associated debris perhaps) crosses the 25h orbit, I think of it leaving some sort of "wake" in the more uniformly distributed 25 hour trail, which we pick up when it crosses the WD, as the 23 min signal. There is no independent evidence, but also no reason why all orbits should cross the WD. However, there are probably insuperable difficulties with this idea that I am unaware of, so I'll shut up. Tom
12. Mark Garlick
13. ZTF Uncovered a New 4.97-hr Transiting WD Vanderbosch, Guidry, Hermes et al. in prep.
14. ZTF Uncovered a New 4.97-hr Transiting WD Vanderbosch, Guidry, Hermes et al. in prep. • Since May 2024 the transits have almost completely disappeared
15. 4.97-hr Porb: Short-Period Structure in Transit? Vanderbosch, Guidry, Hermes et al. in prep.
16. 4.97-hr Porb: Short-Period Structure in Transit? Vanderbosch, Guidry, Hermes et al. in prep.
17. 4.97-hr Porb: Short-Period Structure in Transit? Vanderbosch, Guidry, Hermes et al. in prep.
18. 4.97-hr Porb: Short-Period Structure in Transit? Vanderbosch, Guidry, Hermes et al. in prep.
19. Transiting Debris Around White Dwarfs • Transits appear at short (hr) to long (months) timescales • If connected to tidal disruption, longer à more eccentric • Lots of questions remain with these events • Why the 65th harmonic? • Why are transits grey? Mark Garlick
20. Extra Slides
21. ZTF Uncovered a New 4.97-hr Transiting WD Vanderbosch, Guidry, Hermes et al. in prep.
22. WD Transits Appear Short (Hours) to Long (Months) Discovery papers: Vanderburg, Johnson, Rappaport et al. 2015 Vanderbosch, Hermes, Dennihy et al. 2020 Vanderbosch, Rappaport, Guidry et al. 2021 Farihi, Hermes, Marsh et al. 2022
23. ZTF+Gaia Variability Discovered 5 New Transiting WDs Guidry, Vanderbosch, Hermes, et al. 2021 • Transits appear to recur on either quite long (months) or short (hours) timescales highly eccentric? more recently disrupted? nearer Roche radius? more evolved?
24. WD1054-226: Relentless and complex transits, 25.02 hr Farihi, Hermes, Marsh et al. 2022 • 65th harmonic of Porb is exceptionally strong Re: Incorrect harmonic counting in 1054 paper? 1/11/22, 07:55 Ah, this is an old one! I am not sure who is right. … For instance, a text book I have called "Vibrations & Waves in Physics", by I.G.Main (2nd edition), agrees with us because on page 96 it describes cos(3*omega*t) as the "third harmonic". This is even though it calls cos(omega*t) the "fundamental" and all other terms "harmonics", but still according to it, cos(2*omega*t) would be the second harmonic. I tend to think that the fundamental can also be called the "first harmonic", but I guess that's arguable. … Tom
25. SBSS 1232+563 Hermes, Vanderbosch, Guidry et al. in prep.
26. SBSS 1232+563 Hermes, Vanderbosch, Guidry et al. in prep.
27. WD1145+017, 1st Transiting WD, Found in K2 Campaign 1 Vanderburg, Johnson, Rappaport et al. 2015 • Transits recur every ~4.5 hr (near WD tidal disruption radius)
28. WD1145+017, 1st Transiting WD, Found in K2 Campaign 1 Vanderburg, Johnson, Rappaport et al. 2015 • Transits recur every ~4.5 hr (near WD tidal disruption radius) • <200 WDs in first two 80-day K2 campaigns • WD1145+017 is the only transiting WD among 2200 WDs in K2
29. Gänsicke, Aungwerojwit, Marsh, et al. 2016 >50% • Transits recur every ~4.5 hr (near WD tidal disruption radius) • There are many extended, changing features in the transits WD1145+017, 1st Transiting WD, Found in K2 Campaign 1 TNT/ULTRASPEC
30. Gänsicke, Aungwerojwit, Marsh, et al. 2016 WD1145+017, 1st Transiting WD, Found in K2 Campaign 1 TNT + Warwick 1m
31. ZTFJ0139+5245, 2nd Transiting WD, Part of DAV Search Vanderbosch, Hermes, Dennihy et al. 2020 • Transits recur every ~107 d (debris likely at high eccentricity) • A pulsating WD part of ZTF search within 200pc for new DAV; had one ZTF alert WHT/ISIS