July 12, 2004 Pulsating PMS stars Pulsating Pre-Main Sequence Stars in Young Open Clusters K. Zwintz Institute of Astronomy, Univ. Vienna, Austria [email protected]M. Marconi (INAF Astr. Observatory of Capodimonte, Naples) T. Kallinger (Inst. of Astronomy, Univ. Vienna) W. W. Weiss (Inst. of Astronomy, Univ. Vienna)
15
Embed
Pulsating Pre-Main Sequence Stars in Young Open Clusters
Pulsating Pre-Main Sequence Stars in Young Open Clusters. K. Zwintz Institute of Astronomy, Univ. Vienna, Austria [email protected]. M. Marconi ( INAF Astr. Observatory of Capodimonte, Naples) T. Kallinger (Inst. of Astronomy, Univ. Vienna) - PowerPoint PPT Presentation
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
July 12, 2004 Pulsating PMS stars
Pulsating Pre-Main Sequence Stars in Young Open Clusters
K. ZwintzInstitute of Astronomy, Univ. Vienna, Austria
M. Marconi (INAF Astr. Observatory of Capodimonte, Naples)T. Kallinger (Inst. of Astronomy, Univ. Vienna)W. W. Weiss (Inst. of Astronomy, Univ. Vienna)
July 12, 2004 Pulsating PMS stars
Pre-main Sequence Stars
birthline ZAMShigh degree of activity– photometric & spectroscopic variabilities– interaction with stellar environment– strong IR and/or UV excess– emission lines
part of activity due to pulsation: A-F stars– 24 PMS pulsators known– Periods: 18 min … 6 h– short time in instability strip
ambiguous determination of evolutionary stage for field stars!
July 12, 2004 Pulsating PMS stars
PMS evolutionary stage
1.6, 2.0 and 2.5 MsunMS & post-MS evolutionPMS tracks by D’Antona & Mazzitelli (1994)BE / BEF: blue edge for radial overtones / fundamental modeREobs: empirical red edge
(Breger & Pamyatnykh, 1998)
similar envelope properties differences in interior
log
L/L
su
n
log Teff
July 12, 2004 Pulsating PMS stars
Young Open Clusters
Cluster Properties– same age and distance– age < few 107 yr– main sequence till ~ B9– A-F members lie above
ZAMS
Observed Clusters– NGC 6383 new pulsators!– IC 4996 new pulsators!– NGC 2264
• first detection of period changes
July 12, 2004 Pulsating PMS stars
13.5’
NGC 6383
Observations– CTIO 0.9m telescope– Johnson B & V– CCD time series
photometry– 9 nights
July 12, 2004 Pulsating PMS stars
NGC 6383
Observations– CTIO 0.9m telescope– Johnson B & V– CCD time series
photometry– 9 nights
NGC 6383– Sgr OB1 association– age ~ 1.7 Myr– PMS A-F members– diameter = 20'
2 PMS pulsating cluster members: NGC 6383 170 & 198
(Zwintz et al., 2004)
170
198
July 12, 2004 Pulsating PMS stars
PMS Pulsators in NGC 6383
NGC 6383 170– V = 12.61 mag– A5 IIIp (van den Ancker et al. 2000)
– H in emission
– IR excess– 5 frequencies
• 8.3 … 19.4 c/d
V filter
NGC 6383 198– V = 12.83 mag– no spectral type– f = 19.024 c/d
P ~ 1.26 h
V filter
July 12, 2004 Pulsating PMS stars
NGC 6383: Radial Pulsation Models
freq am p (V) am p (B) phase diff.[c/d] [m m ag] [m m ag]14.376 13.8 17.6 -0.24319.436 11.6 14.9 -0.09213.766 9.8 12.5 0.4748.295 8.6 11.4 0.03517.653 7.7 9.7 -0.050