Unlocking the Secrets of Star Formation: Are We Miscalculating Stellar Masses?

Jordan Keane in Science & Nature June 2025 • 4 min read.

"New research sheds light on the uncertainties and biases in estimating the mass of starless cores and protostellar envelopes, challenging our understanding of stellar evolution."

For decades, astronomers have relied on the measurement of far-infrared thermal dust emission to estimate the masses of dusty objects in space, particularly starless cores and protostellar envelopes—the seeds of future stars. These mass estimates form the basis of our knowledge about how stars originate and evolve from clouds of gas and dust. However, recent research indicates that these measurements might not be as accurate as previously thought.

A study published in Astronomy & Astrophysics delves into the uncertainties and biases inherent in the methods used to derive these crucial mass estimates. The research highlights potential errors stemming from various assumptions and observational limitations, calling for a re-evaluation of how we interpret data related to star formation.

By employing complex radiative transfer models, the study investigates the impact of factors such as non-uniform temperatures, the far-infrared opacity slope, and the methods used for background subtraction. The findings reveal that the derived masses could be significantly off, impacting our broader understanding of star formation processes.

The Problem with Temperature: Why the Uniformity Assumption Fails

Protostellar envelope with temperature gradients.

One of the most significant issues identified in the study is the assumption of a constant temperature within starless cores and protostellar envelopes. Traditional methods assume a single temperature can represent these objects, simplifying calculations and making mass estimations feasible. However, the reality is far more complex. Protostellar envelopes, for example, are centrally heated by accretion luminosity, resulting in a wide range of temperatures within the same object.

The study demonstrates that using a single “color temperature” fails to capture the nuances of these temperature gradients, leading to skewed spectral shapes and inaccurate mass estimations. Regions with higher temperatures emit more intensely at shorter wavelengths, influencing the overall spectral signature and resulting in underestimated masses.

Temperature Gradients: The study highlights how temperatures vary significantly within these objects, especially in protostellar envelopes.
Emission Skew: Warmer regions emit more intensely at shorter wavelengths, distorting the overall spectral shape.
Mass Underestimation: Traditional methods that assume uniform temperatures can underestimate masses by factors of 2 to 5.

This inherent flaw means that many existing models, which rely on simplified temperature assumptions, may need to be adjusted. The study suggests a more nuanced approach, considering temperature variations to derive more accurate mass estimates. While this adds complexity, it is essential for refining our understanding of star formation.

Moving Forward: Towards More Accurate Mass Estimations

The research underscores the necessity for a paradigm shift in how astronomers approach mass estimations of starless cores and protostellar envelopes. It advocates for incorporating the complexities of temperature variations and other factors into models to obtain more precise and reliable results. This will involve refining existing methods and potentially developing new techniques that account for the limitations of current approaches. By addressing these uncertainties and biases, scientists can build a more accurate framework for understanding the intricate processes of star formation and the evolution of cosmic structures.

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This article is based on research published under:

DOI-LINK: 10.1051/0004-6361/201628122, Alternate LINK

Title: Uncertainties And Biases Of Source Masses Derived From Fits Of Integrated Fluxes Or Image Intensities

Subject: Space and Planetary Science

Journal: Astronomy & Astrophysics

Publisher: EDP Sciences

Authors: A. Men’Shchikov

Published: 2016-09-01

Everything You Need To Know

What methods do astronomers traditionally use to estimate the mass of starless cores and protostellar envelopes, and why are these measurements important?

Astronomers traditionally measure far-infrared thermal dust emission to estimate the mass of starless cores and protostellar envelopes. These measurements are crucial as they form the foundation for understanding how stars are born and evolve from gas and dust clouds. These methods, however, may contain inaccuracies.

Why is assuming a uniform temperature within starless cores and protostellar envelopes a problem, particularly concerning protostellar envelopes?

The assumption of uniform temperature within starless cores and protostellar envelopes is problematic. Protostellar envelopes are centrally heated by accretion luminosity, which creates temperature gradients. Using a single "color temperature" doesn't account for these temperature variations, skewing spectral shapes and underestimating masses. For example, warmer areas emit more intensely at shorter wavelengths, and this influences the spectral signature which then results in underestimated masses.

What factors contribute to inaccuracies in estimating the mass of starless cores and protostellar envelopes, according to recent studies?

Using radiative transfer models, the research showed that factors like non-uniform temperatures, the far-infrared opacity slope, and the methods used for background subtraction can introduce errors. The assumption of constant temperature within starless cores and protostellar envelopes can lead to mass underestimations by factors of 2 to 5.

How can astronomers improve the accuracy of mass estimations for starless cores and protostellar envelopes in future studies?

To obtain more precise results, it's crucial to incorporate the complexities of temperature variations and other factors into models. There is a need to refine existing methods and potentially develop new techniques that account for the limitations of current approaches. Understanding the uncertainties and biases will allow for a more accurate framework to explain the intricacies of star formation and cosmic structure evolution.

If the mass of starless cores and protostellar envelopes are underestimated, what aspects of stellar evolution and galactic dynamics could be impacted?

If stellar masses are underestimated, our understanding of stellar evolution would be impacted. This could affect our understanding of the initial mass function, the star formation rate, and the overall chemical evolution of galaxies. The dynamics within star clusters and galaxies could also be affected, which are influenced by the gravitational interactions of stars of different masses.