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Dixon Lane-Meadow Creek, CA, United States
Dixon Lane-Meadow Creek, CA, United States

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Andic A.,BBSO | Andic A.,Big Bear Solar Observatory | Chae J.,BBSO | Chae J.,Big Bear Solar Observatory | And 12 more authors.
Astrophysical Journal | Year: 2011

We detected 2.8 bright points (BPs) per Mm2 in the quiet Sun with the New Solar Telescope at Big Bear Solar Observatory, using the TiO 705.68 nm spectral line at an angular resolution 01 to obtain a 30 minute data sequence. Some BPs formed knots that were stable in time and influenced the properties of the granulation pattern around them. The observed granulation pattern within ∼3″ of knots presents smaller granules than those observed in a normal granulation pattern, i.e., around the knots a suppressed convection is detected. Observed BPs covered ∼5% of the solar surface and were not homogeneously distributed. BPs had an average size of 022, they were detectable for 4.28 minutes on average, and had an averaged contrast of 0.1% in the deep red TiO spectral line. © 2011. The American Astronomical Society. All rights reserved.


Andic A.,BBSO | Chae J.,Seoul National University | Goode P.R.,BBSO
Proceedings of the International Astronomical Union | Year: 2010

Since photospheric bright points (BPs) were first observed, there has been a question as to how are they structured. Are they just single flux tubes or a bundle of the flux-tubes? Surface photometry of the quiet Sun (QS) has achieved resolution close to 0.1" with the New Solar Telescope at Big Bear Solar Observatory. This resolution allowed us to detect a richer spectrum of BPs in the QS. The smallest BPs we observed with TiO 705.68 nm were 0.13", and we were able to resolve individual components in some of the BPs clusters and ribbons observed in the QS, showing that they are composed of the individual BPs. Average size of observed BPs was 0.22". © International Astronomical Union 2011.


Andic A.,BBSO | Andic A.,Big Bear Solar Observatory | Cao W.,BBSO | Cao W.,Big Bear Solar Observatory | And 2 more authors.
Astrophysical Journal | Year: 2011

We detected peaks of oscillatory power at 3 and ∼6.5 minutes in the umbra of the central sunspot of the active region NOAA AR 10707 in data obtained in the near-infrared (NIR) continuum at 1565.7nm. The NIR data set captured umbral dynamics around 50km below the τ500 = 1 level. The umbra does not oscillate as a whole, but rather in distinct parts that are distributed over the umbral surface. The most powerful oscillations, close to a period of ∼6.5, do not propagate upward. We noted a plethora of large umbral dots (UDs) that persisted for ≥30minutes and stayed in the same locations. The peaks of oscillatory power above the detected UDs are located at 3 and 5minute oscillations, but are very weak in comparison with the oscillations of ∼6.5 minutes. © 2011. The American Astronomical Society. All rights reserved.


News Article | October 12, 2016
Site: phys.org

But a team of NJIT scientists now claims that flares in turn have a powerful impact on sunspots, the visible concentrations of magnetic fields on the sun's surface, or photosphere. In a paper published in Nature Communications this week, the researchers argue that flares cause sunspots to rotate at much faster speeds than are usually observed before they erupt. Their observations, based on high-resolution images captured through NJIT's 1.6 meter New Solar Telescope (NST) at Big Bear Solar Observatory (BBSO), come as something of a surprise. The sun's outer layer, or corona, where flares are released, has a plasma density about a hundred million times smaller than that of the photosphere. "It's analogous to the tail wagging the dog. The lower-density regions are much less energetic and forceful," said Chang Liu, a research professor of physics at NJIT and the principal author of the study, "Flare differentially rotates sunspot on Sun's surface." "We do think the rotation of sunspots builds up magnetic energy that is released in form of solar flares, but we have also observed conclusively that flares can cause sunspots to rotate about 10 times faster," he added. "This highlights the powerful, magnetic nature of solar flares." Previous images captured by space solar missions at lower resolutions hinted at this phenomenon, the researchers said, but were inconclusive. "Our new images allow us to not only confirm it, but to also characterize the time-spatial dimension of the sunspot's rotation - to describe its progressive, non-uniform rotation - as the flare travels through it," Liu said. Haimin Wang, a distinguished professor of physics at NJIT and a co-author of the paper, said the observations will prompt scientists to revisit the mechanisms of flares - and the basic physics of the Sun - in a fundamental way. "We used to think that the surface's magnetic evolution drives solar eruptions. Our new observations suggest that disturbances created in the solar outer atmosphere can also cause direct and significant perturbations on the surface through magnetic fields, a phenomenon not envisioned by any major contemporary solar eruption models. This has immediate and far-reaching implications in understanding energy and momentum transportation in eruptions on the Sun and other stars," Wang said. "We will continue to study, and possibly re-interpret, the relationship between the different layers of the Sun." Images captured by NST, the world's largest ground-based solar telescope, are providing an unprecedented glimpse into the complex dynamics of the Sun's many layers, as well as insights into the massive eruptions originating in the solar atmosphere that are responsible for space weather. Last year, scientists at BBSO captured the first high-resolution images of magnetic fields and plasma flows originating deep below the Sun's surface, tracing the evolution of sunspots and magnetic flux ropes through the chromosphere before their dramatic appearance in the corona as flaring loops. Another recent set of images give a first-ever detailed view of the interior structure of umbrae - the dark patches in the center of sunspots - revealing dynamic magnetic fields responsible for the plumes of plasma that emerge as bright dots interrupting their darkness. The high-resolution images show the atmosphere above the umbrae to be finely structured, consisting of hot plasma intermixed with cool plasma jets as wide as 100 kilometers. Explore further: New solar telescope peers deep into the sun to track the origins of space weather More information: Chang Liu et al, Flare differentially rotates sunspot on Sun's surface, Nature Communications (2016). DOI: 10.1038/ncomms13104


Andic A.,BBSO
Proceedings of the International Astronomical Union | Year: 2010

Collision of the magnetic flux tubes in the Quiet Sun was proposed as one of the possible sources for the heating of the solar atmosphere (Furusawa and Sakai, 2000). The solar photosphere was observed using the New Solar Telescope ad Big Bear Solar Observatory. In TiO spectral line at 705.68 nm we approached resolution of 0.1. The horizontal plasma wave was observed spreading from the larger bright point. Shorty after this wave an increase in the oscillatory power appeared at the same location as the observed bright point. This behavior matches some of the results from the simulation of the collision of the two flux tubes with a weak current. © International Astronomical Union 2011.

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