Delaware Asteroseismic Research Center (DARC)


  • Damp05 News
    DAMP05 was completed at the end of May 2012. This run focused on GD165 as a candidate for convective light curve fitting, and GD358 and our ongoing project to monitor its multiplet structure. Run information can be found at DAMP05. GD165 looks like a promising target. We will try using a folded light curve to determine GD165's convective turnover time. For GD358, we are still looking at the data set, but it appears that, while the major modes have not changed, the associated multiplet structures have. We will need some time to sort through this data set.
  • EC14012-1446 paper (XCOV26)
    The EC14012-1446 paper is now published! The reference is 2012, ApJ, 751, 91.
  • 8th WET Workshop
    We are very pleased to announce the 8th Whole Earth Telescope (WET) Workshop to be held in Beijing in early 2013. The preliminary programme is a four day workshop, with two days of traditional talks followed by two days of focused discussion of the pulsating white dwarf G29-38. Participants will be invited to prepare talks or posters directly related to WET science, including pulsating white dwarfs, photometric techniques and data analysis, or proposed applications of the WET. Further details, including specific dates, location, and registration information will be made available in the coming months.
  • XCOV28 News
    XCOV28 was completed in December 2011. This was perhaps the most ambitious WET run ever attempted! We obtained nearly 400 runs from over 30 telescopes over a timebase of 8 weeks. We obtained data on 7 targets (5 DAs and 2 DBs). HS0507+0434B was the initial primary target. Gerard Vauclair is PI for this target. The primary southern targets were EC04207-474B, EC05221-4725, and BPM31594. Light curves and FTs can be found at XCOV28.
  • Damp04
    Damp04 was completed in June 2011. Lightcurves and interesting plots can be found at DAMP04. We obtained about 100 light curves on GD358, over 20 on EC14012-1446, and about 20 on WDJ1524-0030. GD358 never disappoints, and this run was no exception. We saw very interesting changes in excited frequencies on timescales of days. This data set will challenge our understanding of GD358. For EC14012-1446, we found similar pulsation frequencies as for XCOV26 in 2008, but with a much higher amplitude for the dominant frequency at 1633 microhz. WDJ1524 was nearly monoperiodic (as it was in 2010) with an amplitude of about 28 mma.
  • WET Blog
    WET has a blog! It is at WET Blog. We will be using it during runs, so check it out!
  • XCOV27 News
    XCOV27 was completed on June 11, 2009 (started on May 16). This run broke records on the total number of targets observed. The primary target was initially WDJ1524-003 . During our preliminary, 3-site investigation of this target in 2007, WDJ1524-003 was multiple mode, large amplitude, very nonlinear pulsator suitable for light curve fitting (the results in 2007 can be found at 2007 Results). We decided to hold off on this target in 2008 (XCOV26), because it has a close companion and the white dwarf's temperature was uncertain. Since then, we obtained a very nice SOAR spectrum of WDJ1524-003, and, with the help of Detlev Koester, determined a temperature of 11700 K, and log g=8.06, and so felt prepared to designate WDJ1524-003 as a prime target for XCOV27. However, everyone knows that sometimes life throws a curveball. In April 2009, we obtained preliminary XCOV27 data from the PROMPT telescopes in Chile, and discovered that WDJ1524-003 completely changed its pulsation characteristics. Instead of a large amplitude, multimode pulsator, we found a low amplitude pulsator with power confined in a single, apparently unstable short period mode. Following the model of GD358 and the "whoopsie" of 1996, we continued to observe WDJ1524, including obtaining a second spectrum from SOAR. After May 24th, we switched to the DB pulsator WD1654+160. WDJ1524-003 continued to receive considerable coverage (over 250 total hrs) until the end of the run. We did obtain several high signal to noise lightcurves from SOAR, but it is unclear that light curve fitting will be successful for this star.

    Our second target, the pulsating DB WD1654+160, also obtained over 250 hours of observations. We obtained very nice high signal to noise lightcurves from SOAR and WHT. For this target, we may be dealing with some sort of long period amplitude modulation. The data are under analysis.

    Our third target was EC20058, a hot DB pulsator for which we are measuring a rate of period change with the goal of constraining neutrino cooling from a DB white dwarf. We obtained over 40 hours of data on this southern target, including some SOAR beginning of night data. The observations are under analysis by James Dalessio.

    Our fourth target was GD358, the well known bright DB pulsator. These data show that GD358 still has basically the same pulsation structure as we observed in 2006. K=18 and 12 remain dominate, although k=17 has increased amplitude. There may also be a new mode at k=35(??:) but more work remains to confirm this result. The 2009 data resolves the k=8 and 9 triplets, and their splittings/structure remain the same.

    Our fifth target was PG1351, again with the goal of measuring a rate of period change. Our data show that PG1351 has also changed its pulsation characteristics, with the addition of a new mode.

    Our final target was PG1115, yet another DB pulsator, although this one has a significant amount of hydrogen in its atmosphere. PG1115's discovery data reports an amplitude of 20 mma, while we have preliminary data in which we find little evidence of significant pulsation. Early XCOV27 observations also showed little evidence of pulsations, until May 20. SOAR beginning-of-night observations showed a beautiful pulsation with an amplitude of about 10 mma at 1000 seconds. Similar SOAR observations from the previous night show no such pulsation.

  • G29-38 News
    The observations for Susan Thompson's project to measure the inhomogeneity of Ca across the surface of G29-38 are now completed and published. The reference for this paper is 2010, ApJ, 714, 296. This light curve has the longest time base of observations of G29-38 I know of. The results of the campaign are found at DAMP2. You can find the color coded light curves as well as a cool page showing some of the time-resolved spectra.

  • WQED Version 2.0
    The newest version of Wqed has been released. This version has fixed a few bugs and now allows you to reduce 2 and 3 channel phototube data. We highley recommend that all those using Wqed upgrade.

  • For PG1159, we have preliminary linear fits to the main frequencies (webpage). Kepler has the data, so his analysis is ongoing. We also have SALT data on this star, which could prove to be very interesting:)
    For R808, a star that was just supposed to be a target to fill in a few hours here and there turned out to get quite a bit of coverage. R808's FT looks an awful lot like the FT of G38-29, the Nov 2007 target star. Both of these stars have complicated regions of power around 1000 microHz. We are not sure if either of these stars are good candidates for Mike's convection/light curve fitting techniques, but they are interesting in their own rights. We are working on asteroseimology fits to both of these stars.
  • Targets of Opportunity
    One of DARC's goals is to provide support for single site observations of interesting pulsating stars. Single site observations provides us with future targets for full blown WET campaigns. We maintain a list of targets that you have suggested as needing single site observations. The list is on the WET page on the DARC website or at Targets of Opportunity. If you have extra telescope time, please feel free to observe any of these targets. Let us know, and we will pass the information along to the appropriate person.
  • Future Targets
    We are always looking for future targets. If you have any suggestions (and please don't think we are limited to white dwarfs), please send them on. Let us know if you are interested in participating. We do NOT have a formal proposal process (I hate bureacracy:) so please visit our Target proposal page at Proposal Page.  



Please leave your suggestions and comments here