Apurva V. Oza
41 refereed papers, each with a figure taken from the paper itself, a short plain-language summary and a link you can read for free. Group-led marks papers led by me or by a student or postdoc I mentor.
Radio emission from some ultra-cool dwarf stars implies Jupiter-like radiation belts. We show that gas from a tidally heated, Io-like volcanic moon orbiting close to the star could supply that plasma, as could a weak outflow from the star's own ionosphere.
Thermal measurements show the surfaces of icy moons hold heat remarkably poorly. That is only possible if the top layer is a very porous (over 80%), fine-grained (under 1 mm), loosely packed regolith, which matters for choosing landing sites.
How Europa's and Ganymede's oxygen is made, trapped and released: plasma damages surface ice grains, creating voids where O₂ collects, and surface temperature controls when it escapes, explaining why the oxygen varies with latitude and over time.
Could TRAPPIST-1 f, g and h hide oceans beneath ice, and would their water plumes be visible? Interior models favor thin ice shells and shallow oceans on f and g, and localized plume-like outgassing gives stronger JWST transmission signals.
A review of the moons that vent gas: volcanic Io, the ocean worlds Europa and Enceladus, Triton, and Io-like exomoons — from how moons form, to plume evidence, to how plumes let us sample oceans for signs of life.
Sodium, potassium and sulfur dioxide around the hot Saturn WASP-39 b vary by more than tenfold between ground-based and JWST observations. A tidally heated volcanic moon venting gas into a cloud or torus reproduces these changes, much as Io does at Jupiter.
A hybrid plasma simulation of Europa's interaction with Jupiter's magnetosphere, with a realistic atmosphere and ionosphere, checked against Galileo's E4 flyby and used to predict what ESA's JUICE mission will see at Europa in 2032.
Can moons of hot Jupiters survive the planet's migration toward its star? N-body simulations with tides map out when an Io-like satellite survives migration through the protoplanetary disk.
The first Keck/HIRES transit observations of WASP-49 A b detect sodium that is Doppler-shifted relative to the planet, blueshifted at ingress and redshifted at egress, suggesting the gas does not come from the planet's own atmosphere.
Four JWST transits of the sub-Earth L 98-59 b favor a thin sulfur dioxide atmosphere, likely replenished by volcanism and tidal heating at least eight times stronger per unit mass than Io's.
Four nights of VLT/ESPRESSO and HARPS data show WASP-49's sodium signal varies by more than tenfold night to night and, on one night, is redshifted by about 10 km/s relative to the planet, pointing to a source beyond the planet's atmosphere.
The first exoplanet transmission spectroscopy with India's 2-m Himalayan Chandra Telescope: spectra of three hot Jupiters, confirming Rayleigh scattering on WASP-127b and giving the first low-resolution spectrum of KELT-18b.
JWST caught the dayside brightness of the lava world 55 Cancri e changing strongly over days, from undetected to about 100 ppm, in ways that do not fit a simple 3:2 spin–orbit explanation.
A dip in WASP-39b's JWST mid-infrared spectrum beyond 10 µm can be explained by a bright debris disk around the star — a warning that disks can contaminate planet spectra.
JWST's thermal emission spectrum of the rocky super-Earth 55 Cancri e rules out a lava world with only a thin rock-vapor atmosphere and points to a genuine volatile (secondary) atmosphere.
JWST's mid-infrared spectrum of the hot Saturn WASP-39b detects sulfur dioxide at 7.7 and 8.5 µm, confirming that photochemistry shapes hot exoplanet atmospheres.
3-D Monte Carlo simulations (SERPENS) of sodium clouds from volcanic exomoons at eight exoplanets show how an exo-Io's torus would change the observed signal with orbital phase — exomoon phase curves.
Why do comets outgas oxygen? The same radiation processing that traps O₂ in the ice of Europa, Ganymede and Callisto can explain it, suggesting a common origin for trapped oxygen in comets and oxidized icy moons.
CHEOPS observed 55 Cnc e on 29 visits: its visible phase curve changes from orbit to orbit, and a circumstellar dust torus is tested as the cause.
The first dedicated radio search for exoplanet–exomoon interactions: Giant Metrewave Radio Telescope observations of three candidate exo-Io systems set strong upper limits on radio emission.
Simulations of Callisto's hydrogen corona seen by Hubble show that sublimated water cannot explain it but a global H₂ atmosphere can — the first evidence for H₂ at Callisto.
How oxidants made at Europa's surface reach its ocean: brines draining through the ice shell beneath chaos terrains could deliver about 85% of surface oxidants to the ocean within roughly 20,000 years.
A volatile transport model of Neptune's moon Triton, tested against Voyager 2, telescope spectra and stellar occultations, shows its poles act as cold traps for volatile ices.
Proto-Mercury's magma ocean produced an early atmosphere of metals and volatiles; the paper quantifies how quickly that atmosphere escaped.
Earth's tidal pull could have driven intense escape of gas from the molten proto-Moon, reproducing the Moon's measured depletion in potassium and sodium.
A high-resolution survey of the ultra-hot Jupiter WASP-121 b with HARPS detects neutral Mg, Na, Ca, Cr, Fe, Ni and V in its atmosphere.
Sodium lines at exoplanets need not come from a static atmosphere: evaporating gas — escaping, from an exomoon, or in a torus — can produce the same signal, and the D2/D1 line ratio helps tell them apart.
Sodium and potassium seen at hot giant exoplanets could be the signature of hidden volcanic moons (exo-Ios): tidal heating drives far more gas loss than at Io, enough to explain the observed alkali absorption.
A review of where Europa's O₂ comes from and where it goes: radiolysis of surface ice by Jupiter's plasma, trapping in the regolith, and thermal release.
3-D Monte Carlo simulations that include Europa's rotation show O₂ accumulating on the dusk hemisphere, explaining the dusk-over-dawn asymmetry seen by Hubble.
How hot, molten rocky planets outgas CO₂ and H₂O atmospheres, and how that changes their radius and their emission and transmission spectra.
Results of the largest 3.8 µm direct-imaging survey for exoplanets (LEECH, 98 stars): tighter limits on how common giant planets are within about 20 au.
Ganymede's O₂ and water atmosphere changes as it orbits Jupiter, and Jupiter's gravity shapes where the heaviest gases collect.
LEECH imaging of GJ 504 b, the coldest directly imaged exoplanet (about 500 K), constrains its atmosphere and gives evidence for super-stellar metallicity.
Improved escape physics for large Kuiper Belt Objects: which ones can keep their primordial nitrogen atmospheres, and a classification based on volatile loss.
LBT imaging of the four-planet HR 8799 system: new astrometry, orbit fits, and limits on a putative fifth planet.
WISE found a fast-moving nearby star, an ultra-subdwarf M star crossing the sky at about 1.8 arcseconds per year.
Sub-gauss magnetic fields detected on Vega and Sirius A — evidence that ordinary A-type stars can host magnetic fields.
The first detection of a surface magnetic field on an Am star: Sirius A, at about 0.2 gauss.