Loading ...
Sorry, an error occurred while loading the content.
 

Very short period EW stars

Expand Messages
  • Patrick Wils
    A recent paper by S. Rucinski (http://arxiv.org/abs/0708.3020) studies the EW stars discovered by ASAS. One of them, ASAS 083128+1953.1 (see
    Message 1 of 5 , Aug 23 4:48 PM
      A recent paper by S. Rucinski (http://arxiv.org/abs/0708.3020) studies the
      EW stars discovered by ASAS. One of them, ASAS 083128+1953.1 (see
      <http://www.aavso.org/vsx/index.php?view=detail.top&oid=87146>) with a
      period of 0.2178 days may be the shortest period Galactic field EW star
      known. However its amplitude is small (about 0.1 mag), so without a
      detailed study it cannot be excluded it is an elliptical variable.

      A VSX query reveals that ASAS 133105+1215.6 (see
      <http://www.aavso.org/vsx/index.php?view=detail.top&oid=96544&image=poss2ukstu_red>),
      not mentioned in the paper, has a period only about 18 seconds longer. It
      shows a much cleaner EW type light curve with an amplitude of 0.3 mag in
      both the ASAS and the NSVS data. However these surveys measure the
      combined light of GSC 895-616 and GSC 895-686, only 13" apart and with a
      0.7 magnitude difference in V, so that it is not clear which one is the
      variable. Only detailed photometry will tell.

      Another entry in VSX is a possible EW star with a period of only 0.2 days
      (see <http://www.aavso.org/vsx/index.php?view=detail.top&oid=142104>),
      discovered by Walter Cooney. However this star is rather blue accoirding
      to 2MASS, and is therefore likely a DSct with half the period. It lies
      close to NGC 6811, so the data from last year's AAVSO campaign will
      probably resolve this issue.

      Patrick



      ____________________________________________________________________________________
      Take the Internet to Go: Yahoo!Go puts the Internet in your pocket: mail, news, photos & more.
      http://mobile.yahoo.com/go?refer=1GNXIC
    • arne
      ... We have enough data for the NGC6811/Cooney object to decide its nature. The other two EW stars listed above are close to the sun and will take 6 months or
      Message 2 of 5 , Aug 24 7:11 AM
        Patrick Wils wrote:
        > A recent paper by S. Rucinski (http://arxiv.org/abs/0708.3020) studies the
        > EW stars discovered by ASAS. One of them, ASAS 083128+1953.1 (see
        > <http://www.aavso.org/vsx/index.php?view=detail.top&oid=87146>) with a
        > period of 0.2178 days may be the shortest period Galactic field EW star
        > known. However its amplitude is small (about 0.1 mag), so without a
        > detailed study it cannot be excluded it is an elliptical variable.
        >
        > A VSX query reveals that ASAS 133105+1215.6 (see
        > <http://www.aavso.org/vsx/index.php?view=detail.top&oid=96544&image=poss2ukstu_red>),
        > not mentioned in the paper, has a period only about 18 seconds longer. It
        > shows a much cleaner EW type light curve with an amplitude of 0.3 mag in
        > both the ASAS and the NSVS data. However these surveys measure the
        > combined light of GSC 895-616 and GSC 895-686, only 13" apart and with a
        > 0.7 magnitude difference in V, so that it is not clear which one is the
        > variable. Only detailed photometry will tell.
        >
        > Another entry in VSX is a possible EW star with a period of only 0.2 days
        > (see <http://www.aavso.org/vsx/index.php?view=detail.top&oid=142104>),
        > discovered by Walter Cooney. However this star is rather blue accoirding
        > to 2MASS, and is therefore likely a DSct with half the period. It lies
        > close to NGC 6811, so the data from last year's AAVSO campaign will
        > probably resolve this issue.
        >
        We have enough data for the NGC6811/Cooney object to decide its nature.
        The other two EW stars listed above are close to the sun and will
        take 6 months or so before they are in good position for a detailed
        study. We may put them on the SRO program if someone else doesn't
        study them first. Thanks, Patrick!
        Arne
      • Sebastian Otero
        Before Cooney s data confirmation, I bet Patrick is right, this is not EW. But, I think it is delta Scuti with a period of 0.108906, not ELL. There is
        Message 3 of 5 , Aug 24 10:13 AM
          Before Cooney's data confirmation, I bet Patrick is right, this is not EW.
          But, I think it is delta Scuti with a period of 0.108906, not ELL. There is
          assymetry in the lightcurve.
          One more time when a professional paper highlights something that is
          wrong...

          See the EW lightcurve is slightly assymetric:
          http://www.astrouw.edu.pl/cgi-asas/asas_plot_phased?083128+1953.1,asas3,0.217811,1870.610000,0,500,300

          And this is the DSCT lightcurve:
          http://www.astrouw.edu.pl/cgi-asas/asas_plot_phased?083128+1953.1,asas3,0.1089055,1870.610000,0,500,300


          Cheers,
          Sebastian.


          ----- Original Message -----
          From: "Patrick Wils" <patrickwils@...>
          To: <vsx-dis@yahoogroups.com>
          Sent: Thursday, August 23, 2007 8:48 PM
          Subject: [vsx-dis] Very short period EW stars


          >A recent paper by S. Rucinski (http://arxiv.org/abs/0708.3020) studies the
          > EW stars discovered by ASAS. One of them, ASAS 083128+1953.1 (see
          > <http://www.aavso.org/vsx/index.php?view=detail.top&oid=87146>) with a
          > period of 0.2178 days may be the shortest period Galactic field EW star
          > known. However its amplitude is small (about 0.1 mag), so without a
          > detailed study it cannot be excluded it is an elliptical variable.
          >
          > A VSX query reveals that ASAS 133105+1215.6 (see
          > <http://www.aavso.org/vsx/index.php?view=detail.top&oid=96544&image=poss2ukstu_red>),
          > not mentioned in the paper, has a period only about 18 seconds longer. It
          > shows a much cleaner EW type light curve with an amplitude of 0.3 mag in
          > both the ASAS and the NSVS data. However these surveys measure the
          > combined light of GSC 895-616 and GSC 895-686, only 13" apart and with a
          > 0.7 magnitude difference in V, so that it is not clear which one is the
          > variable. Only detailed photometry will tell.
          >
          > Another entry in VSX is a possible EW star with a period of only 0.2 days
          > (see <http://www.aavso.org/vsx/index.php?view=detail.top&oid=142104>),
          > discovered by Walter Cooney. However this star is rather blue accoirding
          > to 2MASS, and is therefore likely a DSct with half the period. It lies
          > close to NGC 6811, so the data from last year's AAVSO campaign will
          > probably resolve this issue.
          >
          > Patrick
        • Sebastian Otero
          ... I messed up things in my last e-mail. Arne talked about the shortest period one suggested by Patrick. Well, the lightcurve for that looks pointy so it is
          Message 4 of 5 , Aug 24 11:13 AM
            > We have enough data for the NGC6811/Cooney object to decide its nature.
            > The other two EW stars listed above are close to the sun and will
            > take 6 months or so before they are in good position for a detailed
            > study. We may put them on the SRO program if someone else doesn't
            > study them first. Thanks, Patrick!

            I messed up things in my last e-mail.
            Arne talked about the shortest period one suggested by Patrick.
            Well, the lightcurve for that looks pointy so it is not EW for sure.

            So.. we have two DSCT stars, not EW.
            The record holder is then ASAS 133105+1215.6, the blended entry.
            Curiously, then we don't actually know which the record holder is!

            Cheers,
            Sebastian..
          • Sebastian Otero
            ... I should have checked everything before sending the e-mails. I checked VizieR and the star is rather red. J-K 0.72 and spectral type K4V. Ellipsoidal
            Message 5 of 5 , Aug 24 11:33 AM
              > I bet Patrick is right, this is not EW.
              > But, I think it is delta Scuti with a period of 0.108906, not ELL. There
              > is
              > assymetry in the lightcurve.
              > One more time when a professional paper highlights something that is
              > wrong...
              >
              > See the EW lightcurve is slightly assymetric:
              > http://www.astrouw.edu.pl/cgi-asas/asas_plot_phased?083128+1953.1,asas3,0.217811,1870.610000,0,500,300
              >
              > And this is the DSCT lightcurve:
              > http://www.astrouw.edu.pl/cgi-asas/asas_plot_phased?083128+1953.1,asas3,0.1089055,1870.610000,0,500,300

              I should have checked everything before sending the e-mails.
              I checked VizieR and the star is rather red. J-K 0.72 and spectral type K4V.
              Ellipsoidal then??

              This confirms there are lots of things difficult to classify out there if we
              only have lightcurves...

              Cheers,
              Sebastian
            Your message has been successfully submitted and would be delivered to recipients shortly.