Expert: Philip Stahl - 12/15/2004

Question
-------------------------
Followup To
Question -
Please tell me about the research that you and other astronomers you know are working on at this moment. I want to know the different questions (that are unanswered or very recently answered) about space that astronomers (you and fellow astronomers) are working on right now.  This is really important to me because I'm looking forward to becoming a professional astronomer.
Answer -
Hello.

"Astronomy" is actually quite a vast discipline to try to explain at one time - even particular areas of current research-  since it includes so many sub-areas: astrometry (the study of star positions and how these change over time with celestial coordinates), celestial mechanics (the prediction of the future positions of the planets, Moon), stellar astrophysics (the study of the physics of the stars, and their evolution, changing properties), solar physics (the study of the Sun, its physics and properties, as well as terrestrial effects), galactic dynamics and astrophysics (the study of the dynamics and physics of the galaxies and galactic clusters), and cosmology, the study of the large scale motions and expansion of the universe including the derivation of its past properties from currently observed ones.

Describing a survey of major-current work in each of these would probably take a small book. What this shows is that like many other scientific disciplines, astronomy has grown and developed beyond simple description or being one simple science. When people become astronomers today, in fact, they have to specialize in one area, say solar physics (my own field) they can't just do astronomy - it's too much! (Though they do get exposed to small segments of various fields, e.g. celestial mechanics, in different university courses)

Naturally, because of this, the education is extensive. Generally those specializing in a sub-discipline will first take a Bachelor's in Physics, for example. That will include all the regular college physics courses, such as: General Physics, Mechanics, Electromagnetic Theory, Thermodynamics and Statistical Mechanics, and Quantum Mechanics. These may or may not be supplemented by actual astronomy courses, i.e. Geodesy, Celestial Mechanics, Radio Astronomy, Astrophysics and Stellar Evolution.

Many mathematics courses will also be required, including: Calculus (usually a full year), Advanced Calculus (a full year), Linear Algebra (usually one semester), Differential Equations, Mathematical Analysis (one full year, including the study of different types of partial differential equations, as well as functions of complex variables and series solutions).

Now, on to what I am working on: currently I am trying to develop a (solar) flare forecasting regime that takes into account a number of quantifiable "observables" including: the degree and rate of magnetic shear in a solar active region, the area of the region, frequency of smaller flares in the region, and appearance and nature of any coronal loops or arches. The aim of this is to expand an update an earlier paper I wrote (1983, in The Journal of the Royal Astronomical Society of Canada) that described the precursors to major solar flares in terms of "triggers".

Outside of my own field of solar physics, the hottest current research is probably in cosmology, and that concerns the discovering of "dark energy" that is accelerating the expansion of the universe.

Dark energy has only recently consolidated as a hypothesis (to account for accelerating expansion of the universe) since there have been confirmations from Type Ia Supernovae data. (See, e.g. Supernovae, Dark Energy and the Accelerating Universe, by Saul Perlmutter, in Physics Today, April, 2003, p. 53.)

I think the June (2003) issue of ASTRONOMY magazine may also have featured an article (more understandable than the preceding one) about it.

If you make a plot of absolute magnitude (vertical axis) against redshfit (z, for the galaxies they occur in ) then type Ia supernovae will be distributed in a particular way.

Such an plot framework might appear:


M(ABS)
!
!
!
!
!
!
!
!
!---------------> Z


Visualize a series of scattered points emanating from the origin up to the upper right. You also have to try to visualize an imaginary diagonal line going from the joined axes to the upper right. In terms of the real data, the type Ia (supernova) points all fall to the LEFT of that line, or in what we call the 'accelerating universe' region. On the other side of the diagonal is the "decelerating region". An additional feature of the accelerating side is 'vacuum energy'.

The cosmological "equation of state" (think of something like the equation of state for an ideal gas, e.g. P = nkT) for this vacuum energy is:

w = (Pressure/ energy density) = -1

But, as Perlmutter and others note, whenever w < ( -1/2) we must have a condition of repulsive energy!

This is the primary feature of dark energy. That the matter affected is being mutually repelled - in total contradiction to the normal behavior of (attractive) gravitation- and this repulsion is accelerating the expansion of the cosmos.

By the time of the COBE (Cosmic Background Explorer) satellite measurements in the early 1990s, it was estimated that nearly 97% of the matter was 'dark'. Dark energy was not yet even on the radar, only dark matter. (Astronomer Fritz Zwicky in 1933 actually laid the original, observational basis for dark matter. His measurements of galaxy clusters highlighted a 'missing mass'. He found that the mass needed to bind a cluster of galaxies together gravitationally was at least ten times the (estimated) apparent mass visible.)

The Boomerang  and MAXIMA UV (ultra-violet) balloon-based measurements to do with type Ia supernovae changed all that. (See, e.g. Physics Today, July, 2000, p. 17). It also caused a re-ordering of the respective contributions of visible and dark matter, and dark energy.

More recent assessments - based on the type Ia data, disclose an assay:

7% - ordinary visible matter

93% - dark component, of which:

- 70% is DARK (vacuum) energy and
- 23% is dark matter


This research is extremely important since it shows that the bulk of the universe is not in the form of ordinary matter, or ordinary energy. Hence, the discoveries will alter our basic physics' perspectives in different sub-areas of cosmology.

I have here provided only a tiny glimpse into two areas (mine and that of many cosmologists) that occupy attention of current researchers. As I said, the details are vast - but you should be able to find books that cover these at your library. It is also a good idea to try to get at least one popular magazine such as 'ASTRONOMY' - which frequently discusses problems of modern astronomical research and the sort of work being done.


My reply question and comments:

Thanks for your reply. I'll looking into all of this and try to understand every bit about it.  Thanks for all the time you took to type about what some astronomers are pondering about. You gave me lots of information and I really appreciate and like that. I'll try to specialize but EVERYTHING about astronomy is so interesting!  

I want to know another thing. What are the job opportunities in Canada and the US (I live in Canada) when it comes to astronomy?  Are any astronomy companies racist to people from the middle east? I don't want to work so hard and end up failing to meet my goal (being a profesional astronomer).

Answer
Hello again.

Unfortunately, the job opportunities here in the U.S. (can't really speak for Canada) are receding, since a number of budget cutbacks have been made toward future funding of pure research areas. This means - in the absence of further grants- that universities will also cut their positions even more.

On top of that, many states are in a situation of huge budget shortfalls because of dwindling tax income - mainly because of a number of recent tax cuts passed by governments, and also tax limiting legislation. This means, like here in my state, unless alternate funding can be found, many academic positions will be lost at state universities.

Re: "astronomy companies" - there are none that I know. Nearly all research is done through universities, so if their budgets are cut, then those positions are lost.

Added to that is the trouble with the Hubble space telescope- which is in need of (human) repairs. Unless astronauts are soon sent to do this in the Space Shuttle, the Hubble will lose altitude in orbit and come crashing down. Hundreds of astronomers that have used and worked with Hubble observations and data will be out of work.

So, all in all, the climate is not at all good for astronomy hiring in the near term, or distant future.

In this light, you may have to ask yourself whether it is really worth pursuing your astronomy education - if there is no guarantee of work, or any position, at the end of it.