Curious Cosmos Editor An asymmetric transit has an ingress, egress or internal shape that fails to mirror the other side of the event. The cause may lie in the star, material around the planet, orbital motion or the measurement process. The shape is a clue to investigate, not a unique diagnosis. First define the expected symmetry A spherical … Read more
Transit duration variations measure changes in how long a planet takes to cross its star. Another planet can produce them by perturbing the orbit, including its orientation. A changing duration is therefore a possible dynamical clue, but it does not identify a hidden planet by itself. Define which duration was measured The full transit duration, … Read more
Transit timing variations, or TTVs, are departures of measured transit midpoints from a constant-period schedule. Gravitational interactions between planets can produce them, allowing astronomers to constrain planetary masses and sometimes infer a companion that does not transit. A late transit alone is not a planet discovery. Build the reference clock first For transit number E, … Read more
An infrared excess means a white dwarf is brighter at infrared wavelengths than its fitted photosphere predicts. Warm circumstellar dust is an important explanation, but excess flux is a measurement, not yet a unique identification of dust. A cool companion or an unrelated background source can produce a competing signal. Start with the expected star … Read more
Yes, some planets survive their star’s red-giant evolution. Distant planets can avoid the expanding envelope and remain around the eventual white dwarf. Survival depends on more than the star’s maximum radius: tides, stellar mass loss, later giant phases and interactions with other planets all affect the outcome. Two competing effects reshape the orbit Tidal dissipation … Read more
Calcium absorption in a white dwarf can reveal material supplied from outside the star. In many cool polluted white dwarfs, the broader evidence points to accreted planetary debris. The calcium line is a chemical clue, not a complete analysis of a destroyed planet and not a direct clock for the planetary system’s age. Identify where … Read more
Planetary debris around white dwarfs is detected through several complementary signals: atmospheric heavy elements, thermal dust emission, circumstellar gas and occultations by orbiting material. Each method samples a different part of the system. Their agreement is more informative than treating any single feature as a complete picture. Match each observation to its claim Signal What … Read more
Many white dwarfs show atmospheric elements that would otherwise sink out of view. In cool stars where external supply is needed, accretion of planetary debris is the leading explanation. “Metal” here means an element heavier than helium, including oxygen and silicon as well as iron. The puzzle is persistence, not merely the presence of atoms … Read more