The Sun from Udaipur

Post by Prof. P. Venkatakrishnan, Senior Professor and Head, Academic Faculty, Udaipur Solar Observatory

Nestling in a small valley surrounded by foothills of the Aravali mountains, and perched on a small island in the middle of lake Fatehsagar in the beautiful town of Udaipur, the Udaipur Solar Observatory is a must-see for all lovers of beauty and the sun. Right now there are 3 telescopes on the island. One is for getting full disk pictures of the solar chromosphere (a layer of hot plasma sandwiched between the cooler photosphere and the super hot one million degree corona). The other is a spar (a moving optical bench tracking the sun) which obtains chromospheric pictures with higher spatial resolution (zoomed picture) of selected portions of the sun. The third telescope is a state-of-the-art solar vector magnetograph, which is a joy for geeks who love gadgets. This telescope not only obtains the maps of the line-of-sight magnetic field, but also the other 2 components of the vector field. These two components allow us to determine the twistedness or curled up nature of the magnetic field. The energy stored in tightly wound up fields sporadically erupts in the form of flares and coronal mass ejections (CMEs). These ejecta travel across the interplanetary medium and hit the earth’s magnetosphere. Under conditions when the inter-planetary magnetic field (IMF) is oppositely directed to the geo-magnetic field, the interaction between the magnetic cloud (evolved CME) and the earth’s magnetosphere results in a magnetic storm, which causes different kinds of disturbances. Our mandate at USO is to 1) monitor the solar chromosphere for flares and 2) do research on solar magnetism to attempt prediction of eruptive phenomena.

There is another subtle aspect of solar activity that is very interesting for global warming: the IMF deflects part of the earth-ward moving cosmic rays and thus modulates the cosmic ray flux as a function of the solar cycle (11 year period). There are some people who are seriously working on the ionization of neutral atoms of earth’s atmosphere by cosmic rays. These ions can act as nucleating centres for water condensation to produce clouds. Question raised is whether cloud coverage is modulated in this way by solar activity? A blunt answer would be no, maybe just a fraction of a percent, compared to regular nucleators like dust and other aerosols. But then, should we completely ignore this effect? Answer is not very clear. There are other empirical relationships between length of the solar cycle (periods range from 9 to 13 years) and the terrestrial temperature, which we solar physicists are nowhere near any understanding. Thus, you can see that this is an exciting area of study, apart from the “regular” studies of sun, where we can now even probe the interior using sound waves (helioseismology: study of solar oscillations). Did you know that the so-called solar neutrino problem (poor unsuspecting Raymond Davis set up an experiment in the ‘70s to detect the neutrinos from the sun and found only a third of the elusive critters: the current understanding is that neutrinos change their “flavor” from electron to tau and muon neutrinos, the early expts detected only electron neutrionos and hence the deficit – new expts which detect all 3 flavors find the total number to as expected by theory of nuclear reactions in the solar core. Happy ending – Ray gets the Nobel, way to go Ray!) was solved because helioseismology restricted the solar models so tightly, that people had to find non-solar reasons for the neutrino deficit.

Currently our observatory has 4 faculty, 3 scientists, 2 technical assistants, 1 lab assistant,  3 tradesmen, & 3 administrative staff. Apart from that we have 4 PhD students (JRF), 2 project associates and 1 library trainee. A “small but happy family”, as the saying goes. Some information is available on our web page. We have just started a small canteen and hope to “keep the wolf at the door”.

Nature lovers will have a great time on our main campus as well as on the island. The main campus building houses the computer centre, several laboratories (adaptive optics, instrumentation, and data archival labs). The instrumentation lab keeps churning out new instruments. The solar vector magnetograph was developed here. The adaptive optics lab is dedicated to developing an adaptive optics system. In this system, the solar images, which get blurred by the turbulence in the earth’s atmosphere, are corrected on-line and stored. Considering that the “turn over time” for the turbulent eddies is a few tens of milliseconds, the whole process of sensing the wave-front aberrations, calculating the compensating voltages to be applied to a deformable mirror, and actually applying the corrections should be done within a few milliseconds. We have achieved this recently using a combination of hardware and software components that would be attractive to computer enthusiasts. We want to make the whole system faster, if possible, using the latest GPUs used in gaming consoles. Anybody interested out there?

The future….?

We will have our new Belgium made 50 cm solar telescope by March 2009. Meanwhile, we are designing and fabricating some superb back-end instruments. We are also into space payloads, jointly developing a space coronagraph with other institutions like IIA, ARIES, and SAID/ISAC/ISRO. We are also going to use a night-time 1.2 m telescope of the Osmania University in novel ways to get solar data (anybody in Hyderabad area interested in participating?). Plenty of challenges for the brave-hearts. To join USO as a PhD student or as a postdoctoral fellow, please look at http://www.prl.res.in for procedures. PhD holders in areas related to plasma physics, instrumentation, astrophysics, quantum physics, wishing to do postdoctoral work on newly opening areas of solar physics can write to me (pvk@prl.res.in) as also those 3^rd year B.Sc and 1^st year M.Sc. students who want to do summer projects