The detection and characterization of a potential sub-stellar Nemesis object are significantly impacted by several observational biases. Here's how each bias affects the search and the proposed methods to mitigate these effects:
Lutz-Kelker Bias: This bias affects distance measurements, particularly for objects with large parallax errors. For a Nemesis object at 15-25kAU, the Lutz-Kelker bias can lead to an underestimation of its distance. To mitigate this, improved parallax measurements from space-based observatories like Gaia, with a precision of about 0.02 milliarcseconds for stars brighter than magnitude 15, can be employed. This precision allows for more accurate distance determinations, crucial for objects at the proposed Nemesis distance.
Malmquist Bias: This bias results from the preferential detection of brighter objects at greater distances, potentially leading to an overestimation of the luminosity of distant objects like Nemesis. To counteract Malmquist bias, increasing the survey depth and duration, such as with the Wide-field Infrared Survey Explorer (WISE), can help detect fainter objects. WISE's sensitivity limit of approximately 16.5 mag in the W1 band allows for the detection of objects with luminosities as low as 0.001 solar luminosities at 25kAU.
Eddington Bias: This bias arises from the preferential detection of brighter objects, which can skew the detection probabilities of faint stars like Nemesis. To reduce the impact of Eddington bias, multi-wavelength observations can be utilized. Combining data from infrared (WISE) and optical (Gaia) surveys can provide a more comprehensive view of potential Nemesis candidates, helping to distinguish between different types of celestial objects.
Additionally, employing advanced statistical methods like Bayesian analysis can account for these biases in data interpretation. Bayesian methods allow for the incorporation of prior knowledge about the expected properties of Nemesis, improving the accuracy of distance and luminosity estimates.
While these strategies could enhance the detection capabilities for a Nemesis star, it's important to note that the existence of Nemesis remains a topic of debate. Some researchers argue that the lack of detection in existing surveys, such as the AllWISE catalog, with a completeness limit of 90% for objects brighter than 15.5 mag at 25kAU, suggests that Nemesis might not exist. However, others point to the potential for undiscovered objects in the outer solar system, supported by anomalies in the distribution of long-period comets and the orbits of certain trans-Neptunian objects.
In conclusion, while the application of these strategies could theoretically improve the detection of a Nemesis star, the debate over its existence continues, with empirical evidence from current surveys providing both support and challenges to the hypothesis.