Searching for Planets Orbiting Vega with the James Webb Space Telescope (2410.16551v2)

Abstract: The most prominent of the IRAS debris disk systems, $\alpha$ Lyrae (Vega), at a distance of 7.7 pc, has been observed by both the NIRCam and MIRI instruments on the James Webb Space Telescope (JWST). This paper describes NIRCam coronagraphic observations which have achieved F444W contrast levels of 3$\times10^{-7}$ at 1\arcsec\ (7.7 au), 1$\times10^{-7}$ at 2\arcsec\ (15 au) and few $\times 10^{-8}$ beyond 5\arcsec\ (38 au), corresponding to masses of $<$ 3, 2 and 0.5 MJup for a system age of 700 Myr. Two F444W objects are identified in the outer MIRI debris disk, around 48 au. One of these is detected by MIRI, appears to be extended and has a spectral energy distribution similar to those of distant extragalactic sources. The second one also appears extended in the NIRCam data suggestive of an extragalactic nature.The NIRCam limits within the inner disk (1\arcsec\ --10\arcsec) correspond to a model-dependent masses of 2$\sim$3 \mj. \citet{Su2024} argue that planets larger even 0.3 MJup would disrupt the smooth disk structure seen at MIRI wavelengths. Eight additional objects are found within 60\arcsec\ of Vega, but none has astrometric properties or colors consistent with planet candidates. These observations reach a level consistent with expected Jeans Mass limits. Deeper observations achieving contrast levels $<10^{-8}$ outside of $\sim$4\arcsec\ and reaching masses below that of Saturn are possible, but may not reveal a large population of new objects.

• The paper demonstrates how JWST’s advanced NIRCam and MIRI observations set stringent limits on the presence of massive planets around Vega.
• The study achieved contrast levels of 3×10⁻⁷ at 1 arcsecond and 1×10⁻⁸ beyond 5 arcseconds, effectively ruling out planets larger than 0.3 Jupiter masses.
• The findings support theoretical models of planet-disk interactions and suggest that deeper observations are needed to detect lower-mass, sub-Jovian bodies.

Observations of Vega for Planetary Exploration Using JWST

The academic paper titled "Searching for Planets Orbiting Vega with the James Webb Space Telescope" outlines a comprehensive observational campaign of the debris disk system surrounding Vega (α Lyrae), utilizing the advanced capabilities of the James Webb Space Telescope (JWST) equipped with both the Near Infrared Camera (NIRCam) and the Mid-Infrared Instrument (MIRI). Vega, a prominent A0V star located at a distance of 7.7 parsecs, has drawn considerable attention due to its well-documented infrared excess indicative of a circumstellar debris disk analogous to our Kuiper Belt.

The primary objective in observing Vega was to investigate the presence of planetary companions that might be contributing to the structure and evolution of the debris disk. Previously, studies, including infrared and submillimeter imaging by the Spitzer and Herschel space telescopes, have provided hints of features within the disk that could suggest the influence of yet-unidentified planets. Using JWST's coronagraphic capabilities, the research team aimed to surpass these earlier observational limits and attain the precision necessary to detect Jupiter-mass objects and potentially even sub-Jovian masses closer to Saturn-like sizes.

The NIRCam observations achieved significant contrast levels, reaching 3 × 10^-7 at 1 arcsecond, corresponding to 7.7 astronomical units (AU) at Vega's distance, and extending to 1 × 10^-8 beyond 5 arcseconds (38 AU). Despite these impressive sensitivity levels, the search resulted in the detection of extended sources likely of extragalactic origin rather than planetary companions. The limits imposed by these observations suggest the absence of massive planets (greater than 0.3 Jupiter masses) that could disrupt the disk's smooth structure observed at MIRI wavelengths.

The research supports theoretical models of planet formation by ruling out large planets in the specified observing range, which could otherwise cause prominent gaps or warps in the disk. The detected exoplanet candidate masses are consistent with the iconic Jeans Mass theory, which proposes a threshold below which fragmentation does not proceed to planet-sized objects. Notably, the investigations implied that any new discoveries within the sensitivity of Saturn-like masses might necessitate deeper observational efforts or alternative detection methodologies.

Looking ahead, the findings emphasize a practical threshold for sub-Jovian planet detection around Vega and similar systems. Future JWST observations, with even longer integration times and potentially employing more refined data reduction approaches, might further explore the lower mass regime, pushing towards Uranus and Neptune analogs in distant orbits. Such efforts would align with population synthesis models predicting an increased occurrence of planetary mass objects formed by gravitational instabilities.

In conclusion, this paper provides critical empirical constraints on the potential mass and location of planets in the Vega system. It paves the way for future detailed studies integrating theoretical models with observational data to enhance our understanding of debris disk-driven planet formation processes and the intricate dynamics within these circumstellar environments.