Astronomers are constantly seeking new ways to detect exoplanets, especially those orbiting nearby stars. This study, led by Dino Mesa and colleagues, explores the use of high-contrast imaging with the SHARK-NIR camera at the Large Binocular Telescope (LBT). The team investigated three stars, HIP 11696, HIP 47110, and HIP 36277, aiming to constrain the properties of potential companions responsible for unusual proper motion behaviors.

Background and Objectives

High-contrast imaging is a powerful technique for identifying large planets orbiting young stars at significant distances. However, most giant planets reside closer to their stars, making detection challenging. To overcome this, the team combined imaging data with astrometric measurements, specifically focusing on proper motion anomalies (PMAs) — unexpected deviations in a star's movement caused by gravitational effects of unseen companions.

The researchers used SHARK-NIR, a near-infrared camera capable of achieving extremely fine resolution, and paired it with another instrument, LMIRCam, to simultaneously capture data in complementary wavelength bands.

Observations and Methodology

The team selected three stars from a catalog of PMAs, ensuring they met specific criteria like proximity to Earth and signs of youth. Observations of these stars were conducted under varying weather conditions using coronagraphic techniques to block out starlight, enabling the detection of faint objects nearby.

For data processing, advanced algorithms like principal component analysis (PCA) were applied to separate potential signals from noise. The researchers also utilized information from the Gaia satellite to further constrain the properties of potential companions.

Results

1. HIP 11696:

   1. A bright object was initially detected but confirmed to be a background star unrelated to the PMA signal.

   2. Based on imaging and astrometric data, the team concluded that a companion between 4 and 16 Jupiter masses likely resides within 2.5 to 28 AU of the star.

2. HIP 47110:

   1. No objects were directly detected around this star. However, the PMA analysis suggested a companion with a mass of 2–10 Jupiter masses at 3–30 AU.

3. HIP 36277:

   1. Two candidate companions were identified. The brighter one was confirmed as bound to the star, but its position ruled it out as the PMA source.

   2. A faint, closer companion was detected but requires further observations for confirmation. Depending on the system's age, this object could be a massive planet or a brown dwarf.

Discussion

The findings highlight the challenges and opportunities in combining imaging and astrometry. While no definitive planets were imaged, the constraints on possible companions provide valuable insights for future studies. Notably, SHARK-NIR demonstrated exceptional capabilities even under suboptimal conditions, achieving sufficient contrasts to probe planetary-mass regimes. For HIP 36277, the results are intriguing but inconclusive, emphasizing the need for follow-up observations to clarify the nature of the detected companions.

Conclusion

This work underscores the potential of SHARK-NIR in exoplanet research, especially when paired with astrometric data. By narrowing down the possible properties of hidden companions, it paves the way for future discoveries with next-generation instruments. The study also showcases the importance of multi-wavelength observations in piecing together the complex puzzle of planetary systems.

Source: Mesa