Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Has SOHO ended a 30-year quest for solar ripples?

The ESA-NASA Solar and Heliospheric Observatory (SOHO) may have glimpsed long-sought oscillations on the Sun’s surface. The data will reveal details about the very core of our central star and it contains clues as to how the Sun formed, 4.6 billion years ago.

The subtle variations reveal themselves as a minuscule ripple in the overall movement of the solar surface. Astronomers have been searching for ripples of this kind since the 1970s, when they first detected that the solar surface was oscillating in and out.

The so-called ‘g-modes’ are driven by gravity and provide information about the deep interior of the Sun. They are thought to occur when gas churning below the solar surface plunges even deeper into our star and collides with denser material, sending ripples propagating through the Sun’s interior and up to the surface. It is the equivalent of dropping a stone in a pond.

Unfortunately for observers, these waves are badly degraded during their passage to the solar surface. By the time g-modes reach the exterior, they are little more than ripples a few metres high. To make matters more difficult, the g-modes take between two and seven hours to oscillate just once. So, astronomers are faced with having to detect a swell on the surface that rises a metre or two over several hours.

Now, however, astronomers using the Global Oscillation at Low Frequency (GOLF) instrument on SOHO think they may have caught glimpses of this behaviour. Instead of looking for an individual oscillation, they looked for the signature of the cumulative effect of a large number of these oscillations.

By analogy, imagine that the Sun was an enormous piano playing all the notes simultaneously. Instead of looking for a particular note (middle C for instance) it would be easier to search for all the ‘C’s, from all the octaves together.

In the piano their frequencies are related to each other just as on the Sun, one class of g modes are separated by about 24 minutes.

“So that’s what we looked for, the cumulative effect of several g modes,” says Rafael A. García, DSM/DAPNIA/Service d’Astrophysique, France. They combined ten years of data from GOLF and then searched for any hint of the signal at 24 minutes. They found it.

“We must be cautious but if this detection is confirmed, it will open a brand new way to study the Sun’s core,” says García.

Until now, the rotation rate of the solar core was uncertain. If the GOLF detection is confirmed, it will show that the solar core is definitely rotating faster than the surface.

The rotation speed of the solar core is an important constraint for investigating how the entire Solar System formed, because it represents the hub of rotation for the interstellar cloud that eventually formed the Sun and all the bodies around it. The next step for the team is to refine the data to increase their confidence in the detection. To do this, they plan to incorporate data from other instruments, both on SOHO and at ground-based observatories.

“By combining data from space (VIRGO and MDI, on SOHO) and ground (GONG and BiSON) instruments, we hope to improve this detection and open up a new branch of solar science,” says García.

Bernhard Fleck | alfa
Further information:

More articles from Physics and Astronomy:

nachricht 'Frequency combs' ID chemicals within the mid-infrared spectral region
16.03.2018 | American Institute of Physics

nachricht Fraunhofer HHI have developed a novel single-polarization Kramers-Kronig receiver scheme
16.03.2018 | Fraunhofer-Institut für Nachrichtentechnik, Heinrich-Hertz-Institut, HHI

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Locomotion control with photopigments

Researchers from Göttingen University discover additional function of opsins

Animal photoreceptors capture light with photopigments. Researchers from the University of Göttingen have now discovered that these photopigments fulfill an...

Im Focus: Surveying the Arctic: Tracking down carbon particles

Researchers embark on aerial campaign over Northeast Greenland

On 15 March, the AWI research aeroplane Polar 5 will depart for Greenland. Concentrating on the furthest northeast region of the island, an international team...

Im Focus: Unique Insights into the Antarctic Ice Shelf System

Data collected on ocean-ice interactions in the little-researched regions of the far south

The world’s second-largest ice shelf was the destination for a Polarstern expedition that ended in Punta Arenas, Chile on 14th March 2018. Oceanographers from...

Im Focus: ILA 2018: Laser alternative to hexavalent chromium coating

At the 2018 ILA Berlin Air Show from April 25–29, the Fraunhofer Institute for Laser Technology ILT is showcasing extreme high-speed Laser Material Deposition (EHLA): A video documents how for metal components that are highly loaded, EHLA has already proved itself as an alternative to hard chrome plating, which is now allowed only under special conditions.

When the EU restricted the use of hexavalent chromium compounds to special applications requiring authorization, the move prompted a rethink in the surface...

Im Focus: Radar for navigation support from autonomous flying drones

At the ILA Berlin, hall 4, booth 202, Fraunhofer FHR will present two radar sensors for navigation support of drones. The sensors are valuable components in the implementation of autonomous flying drones: they function as obstacle detectors to prevent collisions. Radar sensors also operate reliably in restricted visibility, e.g. in foggy or dusty conditions. Due to their ability to measure distances with high precision, the radar sensors can also be used as altimeters when other sources of information such as barometers or GPS are not available or cannot operate optimally.

Drones play an increasingly important role in the area of logistics and services. Well-known logistic companies place great hope in these compact, aerial...

All Focus news of the innovation-report >>>



Industry & Economy
Event News

Ultrafast Wireless and Chip Design at the DATE Conference in Dresden

16.03.2018 | Event News

International Tinnitus Conference of the Tinnitus Research Initiative in Regensburg

13.03.2018 | Event News

International Virtual Reality Conference “IEEE VR 2018” comes to Reutlingen, Germany

08.03.2018 | Event News

Latest News

Wandering greenhouse gas

16.03.2018 | Earth Sciences

'Frequency combs' ID chemicals within the mid-infrared spectral region

16.03.2018 | Physics and Astronomy

Biologists unravel another mystery of what makes DNA go 'loopy'

16.03.2018 | Life Sciences

Science & Research
Overview of more VideoLinks >>>