Episode 550 - Cosmic Collisions and galactic devouring

What happens when two massive planets collide? How can you end up with a gas giant that's super dense and heavy? how can a planet the size of Neptune be as dense as steel? What happens when two giant planets collide at high speed? Watching a black hole devour a star, one bite at a time.  Luca Naponiello, Luigi Mancini, Alessandro Sozzetti, Aldo S. Bonomo, Alessandro Morbidelli, Jingyao Dou, Li Zeng, Zoe M. Leinhardt, Katia Biazzo, Patricio E. Cubillos, Matteo Pinamonti, Daniele Locci, Antonio Maggio, Mario Damasso, Antonino F. Lanza, Jack J. Lissauer, Karen A. Collins, Philip J. Carter, Eric L. N. Jensen, Andrea Bignamini, Walter Boschin, Luke G. Bouma, David R. Ciardi, Rosario Cosentino, Silvano Desidera, Xavier Dumusque, Aldo F. M. Fiorenzano, Akihiko Fukui, Paolo Giacobbe, Crystal L. Gnilka, Adriano Ghedina, Gloria Guilluy, Avet Harutyunyan, Steve B. Howell, Jon M. Jenkins, Michael B. Lund, John F. Kielkopf, Katie V. Lester, Luca Malavolta, Andrew W. Mann, Rachel A. Matson, Elisabeth C. Matthews, Domenico Nardiello, Norio Narita, Emanuele Pace, Isabella Pagano, Enric Palle, Marco Pedani, Sara Seager, Joshua E. Schlieder, Richard P. Schwarz, Avi Shporer, Joseph D. Twicken, Joshua N. Winn, Carl Ziegler, Tiziano Zingales. A super-massive Neptune-sized planet. Nature, 2023; DOI: 10.1038/s41586-023-06499-2 P. A. Evans, C. J. Nixon, S. Campana, P. Charalampopoulos, D. A. Perley, A. A. Breeveld, K. L. Page, S. R. Oates, R. A. J. Eyles-Ferris, D. B. Malesani, L. Izzo, M. R. Goad, P. T. O’Brien, J. P. Osborne, B. Sbarufatti. Monthly quasi-periodic eruptions from repeated stellar disruption by a massive black hole. Nature Astronomy, 2023; DOI: 10.1038/s41550-023-02073-y