AAS Meeting #193 - Austin, Texas, January 1999
Session 2. Galaxy Evolution and Surveys I - Low Redshift
Display, Wednesday, January 6, 1999, 9:20am-6:30pm, Exhibit Hall 1

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[2.13] Boosting the Star Formation Rate by Minor Tidal Interactions

G.H. Rudnick, H. W. Rix (Department of Astronomy and Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721)

For a statistical sample of late type spiral galaxies (Sab to Sbc), we explore whether the global star formation rate (SFR) over the last 0.5~Gyrs is correlated with indicators of recent weak tidal interactions. We obtain integrated spectra (3500Å-5300Å) of our sample galaxies and study the stellar populations and emission line characteristics as a function of the lopsidedness \langle A1/A0 \rangle\phi,r. We quantify the recent SF history of our galaxies by comparing the relative abundance of A stars (via the strength of Balmer absorption), and the abundance of massive stars (via the EW of (H \beta) emission), between symmetric and losided galaxies of the same Hubble type. We find that the recent SFR of a galaxy is correlated to its lopsidedness. Significant lopsidedness is most likely caused by minor tidal interactions and is found in over 20% of the disk galaxy population (Rudnick and Rix, 1998.) Coupled with the short lifetime of lopsided structures, this implies that the average disk galaxy has undergone multiple periods of boosted SFR caused by weak interactions.

The author(s) of this abstract have provided an email address for comments about the abstract: grudnick@as.arizona.edu

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