Radcliffe wave explained

The Radcliffe wave is a neighbouring coherent gaseous structure in the Milky Way, dotted with a related high concentration of interconnected stellar nurseries. It stretches about 8,800 light years.^{[1] [2]} This structure runs with the trajectory of the Milky Way arms.^[3]

It lies at its closest (the Taurus Molecular Cloud) at around 400 light-years and at its farthest about 5,000 light-years (the Cygnus X star complex) from the Sun, always within the Local Arm (Orion Arm) itself, spanning about 40% of its length and on average 20% of its width.^[4] Its discovery was announced in January 2020, and its proximity surprised astronomers.^{[1] [5]}

Formation

Image:Orion Arm.JPG|frame|center|A clickable map of the nearby circa one-sixth outer sector of the galaxy, thus clearly showing the Local Arm (Orion Arm) and neighboring arms - as well as the Great Orion Nebula (as a very luminous feature of the less bright Orion molecular cloud complex) and broad-clouds North America Nebula (and Pelican Nebula) which is an intrinsic part of the Radcliffe wave.

rect 126 149 188 182 Rosette Nebularect 285 116 327 145 Crab Nebularect 243 245 284 274 Orion Nebularect 299 288 345 312 Trifid Nebularect 343 304 384 333 Lagoon Nebularect 393 322 434 353 Omega Nebularect 445 322 494 353 Eagle Nebularect 424 244 483 280 North America Nebularect 293 248 319 266 Rigelrect 225 179 299 246 Orion's Beltrect 331 211 368 234 Polarisrect 318 236 353 259 Sunpoly 302 176 303 241 315 242 361 177 Betelgeuserect 419 222 458 245 Denebpoly 0 123 508 118 637 160 637 217 470 163 0 178 Perseus Armpoly 2 202 460 201 633 261 637 326 408 260 1 258 Orion Armpoly 1 284 397 293 633 360 637 477 541 475 357 413 0 400 Sagittarius Arm

desc bottom-leftScientists do not know how the undulation of dust and gas formed. It has been suggested that it could be a result of a much smaller galaxy colliding with the Milky Way, leaving behind "ripples", or could be related to dark matter.^{[1] [6]} Inside the dense clouds, gas can be so compressed that new stars are born.^[2] It has been suggested that this may be where the Sun originated.^[1]

Many of the star-forming regions found in the Radcliffe wave were thought to be part of a similar-sized but somewhat helio-centric ring which contained the Solar System, the "Gould Belt". It is now understood the nearest discrete relative concentration of sparse interstellar matter instead forms a massive wave.^{[1] [2]}

Discovery

The wave was discovered by an international team of astronomers including Catherine Zucker and João Alves.^[7] It was announced by co-author Alyssa A. Goodman at the 235th meeting of the American Astronomical Society, held at Honolulu^[8] and published in the journal Nature on 7 January 2020.^[9] The discovery was made using data collected by the European Space Agency's Gaia space observatory.^[10]

The wave was invisible in 2D, requiring new 3D techniques of mapping interstellar matter to reveal its pattern using Glue (software).^{[2] [10] [8]} The proximity of the wave surprised astronomers.^{[1] [5]} It is named after the Radcliffe Institute for Advanced Study in Cambridge, Massachusetts, the place of study of the team.^[10]

Structure and movement

The Radcliffe wave contains four of the five Gould Belt clouds:

• Orion molecular cloud complex
• Perseus molecular cloud
• Taurus molecular cloud
• Cepheus OB2

The cloud not within its scope is the Rho Ophiuchi Cloud complex, part of a linear structure parallel to the Radcliffe wave.

Other structures in the wave, further from the local star system, are Canis Major OB1, the North America Nebula and Cygnus X.^[11]

The mass of this structure is on the scale of

\geq 3 x 10 ^{6} . It has a length of 8,800 light-years (2,700 parsecs) and an amplitude of 520 light-years (160 parsecs). The Radcliffe wave occupies about 20% of the width and 40% of the length of the local arm (Orion Arm). The latter is more dispersed as to its interstellar medium than the wave and has further large star-forming regions such as Monoceros OB1, California Nebula, Cepheus Far, and Rho Ophiuchi.

A 2024 paper announced the discovery that the Radcliffe wave is oscillating in the form of a traveling wave.^[12]

See also

• Antlia 2, another giant ripple across the Milky Way's disc found in data from the Gaia space telescope
• List of nearby stellar associations and moving groups
• Great Rift (astronomy)
• Serpens-Aquila Rift

Further reading

• 237–239. 2001.08748. 10.1038/s41586-019-1874-z. 31910431. 2020Natur.578..237A. A Galactic-scale gas wave in the solar neighborhood. Nature. 578. 2020. Alves. João. Zucker. Catherine. Goodman. Alyssa A.. Speagle. Joshua S.. Meingast. Stefan. Robitaille. Thomas. Finkbeiner. Douglas P.. Schlafly. Edward F.. Green. Gregory M.. 7794.

External links

• Interactive map of the Radcliffe wave on the sky
• The Radcliffe Wave informational site created by Harvard University

Notes and References

1. News: 7 January 2020. Astronomers discover huge gaseous wave holding Milky Way's newest stars. The Guardian. 7 January 2020. 0261-3077.
2. News: Paul. Rincon. 7 January 2020. Vast 'star nursery' region found in our galaxy. 7 January 2020. BBC News.
3. Web site: Brandon. Specktor. 7 January 2020. 7 January 2020. Mysterious 'Wave' of Star-Forming Gas May Be the Largest Structure in the Galaxy. livescience.com.
4. Web site: Brandon. Specktor. 7 January 2020. 7 January 2020. Mysterious 'Wave' of Star-Forming Gas May Be the Largest Structure in the Galaxy. livescience.com.
5. Web site: Hannah. Osborne. Something appears to have collided with the Milky Way and created a huge wave in the galactic plane. 7 January 2020. Newsweek.
6. Web site: Something Appears to Have Collided with the Milky Way and Created a Huge Wave in the Galactic Plane. 2020-01-08. Radcliffe Institute for Advanced Study at Harvard University. en. 2020-01-09.
7. Web site: Bennett. McIntosh. 7 January 2020. An Interstellar Ribbon of Clouds in the Sun's Backyard. 7 January 2020. Harvard Magazine.
8. Web site: Ashley. Strickland. 7 January 2020. Astronomers discover giant wave-shaped structure in the Milky Way. CNN. 7 January 2020 .
9. Web site: 7 January 2020. New map of Milky Way reveals giant wave of stellar nurseries. Phys.org.
10. News: Dunn. Marcia. Titanic wave of star-forming gases found in Milky Way. 8 January 2020. Associated Press. 8 January 2020. 0447-5763. Japan Times Online.
11. Alves. João. Zucker. Catherine. Goodman. Alyssa A.. Speagle. Joshua S.. Meingast. Stefan. Robitaille. Thomas. Finkbeiner. Douglas P.. Schlafly. Edward F.. Green. Gregory M.. January 2020. A Galactic-scale gas wave in the Solar Neighborhood. Nature. en. 578. 7794. 237–239. 2001.08748. 10.1038/s41586-019-1874-z. 31910431. 2020Natur.578..237A.
12. Ralf . Konietzka . Alyssa A. . Goodman . Catherine . Zucker . Andreas . Burkert . João . Alves . Michael . Foley . Cameren . Swiggum . Maria . Koller . Núria . Miret-Roig . The Radcliffe Wave is Oscillating . . 10.1038/s41586-024-07127-3 . 20 February 2024. 628 . 8006 . 62–65 . 38378142 . 2402.12596 .