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The Fascinating Life of WR 138: A Stellar Duo

Explore the unique characteristics and dynamics of the WR 138 binary star system.

Amanda Holdsworth, Noel Richardson, Gail H. Schaefer, Jan J. Eldridge, Grant M. Hill, Becca Spejcher, Jonathan Mackey, Anthony F. J. Moffat, Felipe Navarete, John D. Monnier, Stefan Kraus, Jean-Baptiste Le Bouquin, Narsireddy Anugu, Sorabh Chhabra, Isabelle Codron, Jacob Ennis, Tyler Gardner, Mayra Gutierrez, Noura Ibrahim, Aaron Labdon, Cyprien Lanthermann, Benjamin R. Setterholm

― 5 min read


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In the vastness of space, we have stars that are like the high-energy rock stars of the universe. Among these stars are the Wolf-Rayet stars, known for being massive and having lost their hydrogen layers, leaving them as luminous and hot celestial bodies. This story focuses on one such star, WR 138, which is part of a binary system. This means it has a partner star, and they are in a dance around each other in the cosmos.

Meet the Stars

WR 138 is a type of star that loves to showcase its impressive features, sort of like a peacock but with more nuclear fusion going on. It is located in the constellation Cygnus, also known as the swan. This star is special because it is rich in nitrogen and forms a binary system with an O-type star, which is a hotter and more massive type of star. Together, they create an elaborate celestial spectacle.

What Makes WR 138 Tick?

The life of WR 138 and its companion is marked by the loss of mass, which can happen for reasons like strong Stellar Winds or interactions between the two stars. Imagine them as two rock stars in a band-sometimes they collaborate, and sometimes they overshadow each other. With a period of around 4 years, WR 138 and its partner star spin around one another, and their relationship is filled with twists and turns, much like a soap opera in the sky.

The Quest for Understanding

The basic idea behind studying WR 138 is to figure out how stars like it evolve and what makes them special. Through advanced methods like Interferometry, which is a fancy way of saying "seeing tiny details of stars," scientists are able to get great insights into the orbits and masses of these stars.

Chasing the Light

Using the CHARA Array, a group of telescopes working together, researchers collected data to understand WR 138 better. This involved observing the stars at different times, similar to how you might take a series of photos at a family reunion. The goal was to get a full picture of how the stars move and interact with each other.

The Stars in Motion

The measurements showed that WR 138 and its companion star are separated by a specific distance, with WR 138 being a bit heavier than its partner. This relationship helps scientists understand how they formed and how they influence each other. Picture it like two dancers: one leads while the other follows, creating a dynamic movement that's fascinating to observe.

What the Data Reveals

From the observations, researchers were able to determine the sizes of the stars and their precise movements. They found that WR 138 had a mass of about 13.9 times that of our Sun, while its companion had a mass of approximately 26.3 times the Sun's mass. That's like comparing a hefty elephant to a massive whale!

Stellar Evolution

The stars in this binary system have an interesting backstory. They may have lost their outer layers over time, likely due to strong winds or through a complex relationship with one another. The two stars likely started off as bigger and brighter stars but have evolved into their current forms after many cosmic years of change.

Comparing the Stars

In the broader context, WR 138's characteristics are compared to similar stars in other Binary Systems. This way, researchers can get a better grasp of what makes WR 138 unique. Additionally, comparisons to models help to see if this star matches expectations based on current theories of star formation.

The Role of Mass Loss

Mass loss is a significant factor in the lives of these stars. It plays a vital role in their evolution and the way they behave in relation to each other. Mass loss can occur through various means, like strong stellar winds or interactions when one star pulls away material from another. It's somewhat like a couple sharing a pizza-sometimes one takes a larger slice than the other, and it can affect how both feel in the end.

The Dance of Orbits

The measurements taken also help to create a visual representation of the stars' orbits around one another. You can think of it as drawing up a dance floor plan to see how the stars move together. With the data collected, the rotation speed, distance, and other details provide clarity on their relationship, making them easier to study and understand.

Spectroscopic Measurements

To get further insights, researchers also used Spectroscopy, a method of studying how stars emit light at different wavelengths. This helps to determine the composition and properties of the stars in the binary system. The light acts like a fingerprint, revealing the unique characteristics of each star.

An Ongoing Story

The tale of WR 138 is still unfolding. New findings will continue to shed light on how these stars evolved and their place in the grand scheme of the universe. Every observation provides more pieces to the puzzle, allowing researchers to build a more comprehensive story.

The Cosmic Connect

By comparing WR 138 to other binary systems, researchers can assess the bigger picture of how massive stars behave. This helps scientists understand the evolutionary paths of stars in various environments and what factors influence their futures.

Future Studies

Future observations will likely delve deeper into this star system, catching more captivating glimpses of these stellar rock stars. With advanced technology and ongoing research, the secrets of WR 138 will unravel further, revealing even more about the life cycles of these magnificent stars.

Conclusion

In the end, the study of WR 138 and its companion provides not just answers but also raises questions about how stars live, interact, and evolve together. The universe is full of drama, and with the help of scientists, we get to witness the exciting dance of stars from the comfort of Earth. Who knew that the heavens could be so entertaining?

Original Source

Title: Visual Orbits of Wolf-Rayet Stars II: The Orbit of the Nitrogen-Rich WR Binary WR 138 measured with the CHARA Array

Abstract: Classical Wolf-Rayet stars are descendants of massive OB-type stars that have lost their hydrogen-rich envelopes, and are in the final stages of stellar evolution, possibly exploding as type Ib/c supernovae. It is understood that the mechanisms driving this mass-loss are either strong stellar winds and or binary interactions, so intense studies of these binaries including their evolution can tell us about the importance of the two pathways in WR formation. WR 138 (HD 193077) has a period of just over 4 years and was previously reported to be resolved through interferometry. We report on new interferometric data combined with spectroscopic radial velocities in order to provide a three-dimensional orbit of the system. The precision on our parameters tend to be about an order of magnitude better than previous spectroscopic techniques. These measurements provide masses of the stars, namely $M_{\rm WR} = 13.93\pm1.49M_{\odot}$ and $M_{\rm O} = 26.28\pm1.71M_{\odot}$. The derived orbital parallax agrees with the parallax from \textit{Gaia}, namely with a distance of 2.13 kpc. We compare the system's orbit to models from BPASS, showing that the system likely may have been formed with little interaction but could have formed through some binary interactions either following or at the start of a red supergiant phase, but with the most likely scenario occurring as the red supergiant phase starts for a $\sim 40M_\odot$ star.

Authors: Amanda Holdsworth, Noel Richardson, Gail H. Schaefer, Jan J. Eldridge, Grant M. Hill, Becca Spejcher, Jonathan Mackey, Anthony F. J. Moffat, Felipe Navarete, John D. Monnier, Stefan Kraus, Jean-Baptiste Le Bouquin, Narsireddy Anugu, Sorabh Chhabra, Isabelle Codron, Jacob Ennis, Tyler Gardner, Mayra Gutierrez, Noura Ibrahim, Aaron Labdon, Cyprien Lanthermann, Benjamin R. Setterholm

Last Update: 2024-11-01 00:00:00

Language: English

Source URL: https://arxiv.org/abs/2411.01062

Source PDF: https://arxiv.org/pdf/2411.01062

Licence: https://creativecommons.org/licenses/by/4.0/

Changes: This summary was created with assistance from AI and may have inaccuracies. For accurate information, please refer to the original source documents linked here.

Thank you to arxiv for use of its open access interoperability.

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