stars

H-R Diagram

Discipline: 
Education

Having the information about spectral types was useful, but astronomers wanted to look for trends in the data. In 1911 Ejnar Hertzsprung plotted the absolute magnitude of stars against their colors. Two years later Henry Norris Russell independently did a similar graph using spectral types. Graphs of this type are known as Hertzsprung-Russell diagrams or H-R diagrams.

Tags: 
stars
luminosity
temperature
Hertzsprung
Russell
white dwarf
blue giants
red giants
supergiants

Types of Stars

Discipline: 
Education

Astronomers have always been fascinated by the different sizes and colors of stars that they observed. In 1817 an German instrument maker named Joseph Fraunhofer attached a spectroscope to a telescope and pointed it at the stars. He found that different stars have different absorption lines in their spectra. At first astronomers did not understand why different stars would have different absoprtion lines. Nevertheless in the early 1900s, a team of astronomers at Harvard College Observatory started a project to examine the spectra of hundreds of thousands of stars.

Tags: 
stars
spectra
spectral class
temperature
Henry Draper
Annie Jump Cannon
Antonia Maury
Edward Pickering

Temporal Variability of Stars and Stellar Systems

Although the Sun is our closest star by many orders of magnitude and despite having sunspot records stretching back to ancient China, our knowledge of the Sun's magnetic field is far from complete. Indeed, even now, after decades of study, the most obvious manifestations of magnetic fields in the Sun (e.g. sunspots, flares and the corona) are scarcely understood at all. These failures in spite of intense effort suggest that to improve our grasp of magnetic fields in stars and of astrophysical dynamos in general, we must broaden our base of
White Paper submitted to the Stars and Stellar Evolution Panel of the Astro2010 Decadal Survey

FTN image makes Astronomy Picture of the Day

An image taken with LCOGT's Faulkes Telescope North was the NASA Astronomy Picture of the Day for June 26th 2008. You can view the APOD site here:

http://apod.nasa.gov/apod/

The image of the planetary nebula M27 was taken by top UK astrophotographer Nik Szymanek. The final image was a mosaic of 4 frames (each frame made up stacked images), using the narrow band filters H alpha, H beta and OIII.

 

WASP-5b: a dense, very hot Jupiter transiting a 12th-mag Southern-hemisphere star

We report the discovery of WASP-5b, a Jupiter-mass planet orbiting a 12th-mag G-type star in the Southern hemisphere. The 1.6-d orbital period places WASP-5b in the class of very hot Jupiters and leads to a predicted equilibrium temperature of 1750K. WASP-5b is the densest of any known Jovian-mass planet, being a factor of 7 denser than TrES-4, which is subject to similar stellar insolation, and a factor of 3 denser than WASP-4b, which has a similar orbital period.
Monthly Notices of the Royal Astronomical Society: Letters, Volume 387, Issue 1, pp. L4-L7

Parameters and Predictions for the Long-Period Transiting Planet HD 17156b

We report high-cadence time series photometry of the recently discovered transiting exoplanet system HD 17156, spanning the time of transit on UT 2007 October 1, from three separate observatories. We present a joint analysis of our photometry, previously published radial velocity measurements, and times of transit center for three additional events. Adopting the spectroscopically determined values and uncertainties for the stellar mass and radius, we estimate a planet radius of Rp=1.01+/-0.09 RJup and an inclination of i=86.5+1.1-0.7 deg.
The Astrophysical Journal, Volume 681, Issue 1, pp. 636-643

The binary properties of massive stars

The physics of star formation remains an outstanding problem within astrophysics. This problem is particularly acute for the production of OB stars (with masses in excess of 20 times that of the Sun); where the apparent brevity of the process (<100,000 yrs) and the presence of significant extinction (>>30 visual magnitudes) due to their birth clouds, make observations of high mass protostars highly challenging.

Monitoring Magnetic Field Activity Cycles of Pre Main Sequence Stars

By using the surface features as an indication of magnetic field strength in Pre Main Sequence (PMS) stars, using the LCOGT network, a long-term photometric monitoring campaign with semi-regular cadence will allow one to measure magnetic activity cycles. As the surface features get more prevalent and then disappear, the amplitude of the brightness modulation they create will increase and decrease. The period of this amplitude variation should be a good proxy for magnetic field activity.

Themed observing

Discipline: 
Education
Country: 
USA

On a themed observing day, the whole observing day (or night depending on your point of view) is dedicated to achieving a particular goal; for example observing a particular asteroid to plot a light curve, or imaging different parts of a large galaxy to make a mosaic.

The observing sessions are booked up by the FT Team and allocated to users who are interested in participating in the project. Users who are allocated sessions (given on a first come first served basis) are given educational material based around the project and are given certain co-ordinates to observe.

Tags: 
asteroids
stars

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