Since their discovery Be stars have been systematically examined in long-term observing programs. It is now clear that these stars exhibit obvious changes in their spectra on timescales of a few years to decades. In particular, H and H emission lines can unpredictably and dramatically change in strength and appearance. In addition, no connection has been found between variations in emission lines and changes in brightness as shown by light curves.

Phase transitions from B to Be and from Be to B can be relatively easily observed by amateurs. This can be done by following the intensity of hydrogen emission. The author has measured H emission strength of different Be stars with an objective prism spectrograph for several years. The goal is to get a sense of the long-term behavior of some well known stars. This is a desirable project because professional astronomers have limited observation time which causes gaps in coverage and loss of continuity in the measurements. Many Be stars are incompletely observed. The plots show how the program stars changed over time as observed by the author and others.

• Figure 1 -  Psc:  Without being able to fill a 17-year gap in observations of  Psc, all that can be concluded from this figure is that the mean H equivalent width was about 3 Å larger at the end of the period than it was at the beginning.

  

• Figure 2 - 28 Tau:  Equivalent widths through JD 2444651 were fairly stable. Subsequently they rose and fell through a range of 36 Å. At JD 2451586 28 Tau was at the close of a B phase.

  

• Figure 3 -  Dra:  Prior to JD 2450123 there are not enough observations to show cyclical behavior in  Dra. Coverage after that date may indicate its presence.

  

• Figure 4 -  CMi:  At JD 2451495  CMi was probably in the B phase. The Be phase may have been reached when the equivalent width rose to 7 Å (JD 2451849). The transformation appears to have taken about a year.

  

• Figure 5 - EW Lac:  Equivalent widths from JD 2442761 to 2444588 were greater by a mean of about 20 Å over those in the period JD 2450240 to 2451705. The author's measurements starting JD 2450240 reveal variability in EW Lac of about 0.3 Å/day.

  

• Figure 6 -  Tau:  Current equivalent widths for  Tau  agree with those of Slettebak and Reynolds and Andrillat.

  

• Figure 7 - 120 Tau:  The author's measurements for 120 Tau agree with those of Slettebak and Reynolds and Andrillat.

  

• Figure 8 - 11 Cam:  Only Andrillat's much earlier measurements of 11 Cam were available to the author. At about 24 Å, the last equivalent width peak (JD 2451468) seems to indicate the Be phase. Future measurements may show the Be to B transformation.

  

• Figure 9 - o Cas:  The equivalent width measurements of Slettebak and Reynolds probably coincide with the B phase of o Cas. The author observed transformation to the Be phase in which H equivalent width reached 44 Å. It appears that this phase lasted for about 330 days.

  

• Figure 10 - 66 Oph:  Over about 30 years 66 Oph underwent a long cycle with a range of almost 40 Å. The coverage is not good enough to permit conclusions about short time variations.

  

• Figure 11 -  Per:  In this plot the extreme range for H equivalent widths in  Per is about 50 Å. Frequent observations after JD 2450000 reveal much short-term activity. Considering these facts, it is no surprise that significant differences exist between the results of different observers. At the suggestion of Dr. R. Hanuschik, the author is using a new grating spectrograph (R=16000) to search for V/R variations on a timescale of minutes. A similar effort is being made with  Tau.

  Figure 12 -  Tau:  The author's results are similar to those of Slettebak and Reynolds, Andrillat, and Lacy. His more frequent observations show interesting short time period variations. As with  Per, he is attempting to detect V/R variations on a timescale of minutes.

  

• Figure 13 - 48 Per:  Although the author has followed 48 Per for about four years, the sketchy picture that emerges when his observations are combined with others makes it difficult to draw any conclusion about activity in this object.

  

• Figure 14 -  Cas:  Excluding the outburst around JD 2449800, the H equivalent width in  Cas showed a steady linear decline over 2300 days. Equivalent width decreased by an average of 9.13 Å for the period.

The positive response of professional astronomers to observational results from amateur astronomers who do spectroscopy shows that the possibility of scientific contributions by amateurs is growing. This motivated the author to build a spectrograph for the specific purpose of observing line profiles in Be-stars. High spectral resolving power and high signal to noise are called for. The spectrograph is attached to a 20-cm Schmidt-Cassegrain (1:3,8) telescope. Here are details of the instrument.

• Mounting: Schmidt-Cassegrain focus
• Slit: None
• Collimator optics: f = 50 mm, 1:3,5, Pentacon photographic lens
• Reflection grating: 1200 g/mm
• Grating position: Fixed and centered at 6563Å
• Imaging optics: f = 135 mm, 1:3,5, Soligor photographic lens
• CCD pixel size: 9 x 9 microns
• Total weight: 1300 g
• Dispersion: 43 Å/mm; 0.391126 Å/pixel
• Resolving power: 16000

Following are H emission line profiles for some popular Be stars as observed with this instrument.