Eleven New γ Doradus Stars

Abstract

We present new high-dispersion spectroscopic and precise photometric observations to identify 11 new Doradus variables. Seven of these new Doradus stars appear to be single, three are primaries of single-lined binaries, and one has two distant visual companions; none are double-lined or close visual binaries. Several of the stars show spectroscopic line-profile and low-amplitude radial velocity variability indicative of pulsation. All 11 stars are photometrically variable with amplitudes between 8 and 93 mmag in Johnson B and periods between 0.398 and 2.454 days. One star is monoperiodic; the rest have between two and five independent periods. The variability at all periods approximates a sinusoid, although three of the stars exhibit cycle-to-cycle variation in the level of maximum brightness, similar to the Blazhko effect observed in some RR Lyrae stars. We provide a new tabulation of all 54 Doradus stars confirmed to date and list some of their properties. All are dwarfs or subgiants and lie within a well-defined region of the H-R diagram that overlaps the cool edge of the Scuti instability strip. Four of the new Doradus variables from this paper also lie within the Scuti instability strip but do not exhibit the additional higher frequency variability typical of Scuti stars. The variability type of several of these stars given in the General Catalog of Variable Stars and in SIMBAD should now be revised.

Constraining the near-core rotation of theγDoradus star 43 Cygni using BRITE-Constellation data

“…The resulting combined, normalized spectrum has a S/N of 590 calculated from 5820 to 5821 Å and was used to determine the fundamental parameters and abundances for 43 Cygni. With our spectroscopic data, we also can verify previous reports (e.g., Henry et al 2005;Gerbaldi et al 2007) that 43 Cyg is a single star.…”

“…Using 230 spectra obtained over two years, Jankov et al (2006) studied the line profile variations, detected an additional frequency and attempted a first spectroscopic mode identification. The authors reported a frequency at 1.61 d −1 to be an = 5(±1) and m = 4(±1) and the frequency at 1.25 d −1 -which is f 1 of Henry et al (2005) -to be an = 4(±1) and m = 3(±1) mode. Cuypers et al (2009) confirmed the presence of the previously identified pulsation frequencies using photometric time series in the Geneva system.…”

“…Gerbaldi et al (2007) verified that 43 Cyg is a single star from TD1 UV observations. Henry et al (2005) identified the star as a (single) γ Doradus pulsator and detected three main frequencies at f 1 = 1.25054 d −1 , f 2 = 1.29843 d −1 and f 3 = 0.96553 d −1 , using photometric time series in the Johnson B and V filters. Using 230 spectra obtained over two years, Jankov et al (2006) studied the line profile variations, detected an additional frequency and attempted a first spectroscopic mode identification.…”

Analysis of MERCATOR data - Part II: variable A & F stars

“…A few stars from other lists (Henry and Fekel 2002;Koen and Eyer 2002) were added as well. In the mean time, the γ Dor character of most of our targets (apart from a few δ Scuti stars) has been confirmed, and they are already listed as bona fide γ Dor stars by Henry et al (2005). Hence, the main goal of our observations is to obtain well defined light curve parameters (frequencies, amplitudes, phases) in the 7 colours of the Geneva photometric system for all the observed variable stars.…”

“…In Part I (De Cat et al these proceedings) the analysis of the observations of the variable B stars is discussed. In Part II (this article) the analysis of variable A and F stars is presented, with emphasis on the pulsating γ Doradus stars, hereafter γ Dor stars (see Henry et al (2005) for a class description and a recent list).…”