The young open cluster Trumpler 3

We present a photometric and spectroscopic study of the poorly investigated open cluster Trumpler~3. Basic parameters such as the age of $70\pm10$ Myr, the color excess $E(B-V)=0.30\pm0.02$ mag, the distance of $0.69\pm0.03$ kpc and the limiting radius of 12' were redetermined and compared with previous preliminary studies. The distance of $0.65\pm0.09$ kpc was determined independently by spectral parallaxes. Simultaneously, our analysis allowed us to estimate a total number of members to be $N_{\rm{tot}}=570\pm90$ and a total mass of the cluster to be $M_{\rm{tot}}=270\pm40$ $\rm{M}_{\odot}$. We also determined a state of cluster's dynamical evolution. We conclude that Trumpler~3 is a young low-massive stellar ensemble with a typical mass function slope, located near to the outer edge of the Galaxy's Orion Spur. As a result of a wide-field search for short period variable stars, 24 variables were discovered in the cluster's area. Only one of them -- a variable of the $\gamma$-Dor type -- was found to be a likely cluster member

Frequency Analysis of Reflex Velocities of Stars with Planets

Since it has become possible to discovery planets orbiting nearby solar-type stars through very precise Doppler-shift measurements, the role of methods used to analyze such observations has grown significantly. The widely employed model-dependent approach based on the least-squares fit of the Keplerian motion to the radial-velocity variations can be, as we show, unsatisfactory. Thus, in this paper, we propose a new method that may be easily and successfully applied to the Doppler-shift measurements. This method allows us to analyze the data without assuming any specific model and yet to extract all significant features of the observations. This very simple idea, based on the subsequent subtraction of all harmonic components from the data, can be easily implemented. We show that our method can be used to analyze real 16 Cygni B Doppler-shift observations with a surprising but correct result which is substantially different from that based on the least-squares fit of a Keplerian orbit. Namely, using frequency analysis we show that with the current accuracy of this star's observations it is not possible to determine the value of the orbital eccentricity which is claimed to be as high as 0.6.Comment: AASLaTeX + 5 figures (eps files), 22 pages, two figures delated, typos corrections; accepted for publication in Ap

CCD BV survey of 42 open clusters

We present results of a photometric survey whose aim was to derive structural and astrophysical parameters for 42 open clusters. While our sample is definitively not representative of the total open cluster sample in the Galaxy, it does cover a wide range of cluster parameters and is uniform enough to allow for simple statistical considerations. BV wide-field CCD photometry was obtained for open clusters for which photometric, structural, and dynamical evolution parameters were determined. The limiting and core radii were determined by analyzing radial density profiles. The ages, reddenings, and distances were obtained from the solar metallicity isochrone fitting. The mass function was used to study the dynamical state of the systems, mass segregation effect and to estimate the total mass and number of cluster members. This study reports on the first determination of basic parameters for 11 out of 42 observed open clusters. The angular sizes for the majority of the observed clusters appear to be several times larger than the catalogue data indicate. The core and limiting cluster radii are correlated and the latter parameter is 3.2 times larger on average. The limiting radius increases with the cluster's mass, and both the limiting and core radii decrease in the course of dynamical evolution. For dynamically not advanced clusters, the mass function slope is similar to the universal IMF slope. For more evolved systems, the effect of evaporation of low-mass members is clearly visible. The initial mass segregation is present in all the observed young clusters, whereas the dynamical mass segregation appears in clusters older than about log(age)=8. Low-mass stars are deficient in the cores of clusters older than log(age)=8.5 and not younger than one relaxation time.Comment: 13 pages, 8 figure

Planets Around the K-Giants BD+20 274 and HD 219415

We present the discovery of planet-mass companions to two giant stars by the ongoing Penn State- Toru\'n Planet Search (PTPS) conducted with the 9.2 m Hobby-Eberly Telescope. The less massive of these stars, K5-giant BD+20 274, has a 4.2 MJ minimum mass planet orbiting the star at a 578-day period and a more distant, likely stellar-mass companion. The best currently available model of the planet orbiting the K0-giant HD 219415 points to a Jupiter-mass companion in a 5.7-year, eccentric orbit around the star, making it the longest period planet yet detected by our survey. This planet has an amplitude of \sim18 m/s, comparable to the median radial velocity (RV) "jitter", typical of giant stars.Comment: 5 figures, 13 pages, accepted by the Astrophysical Journal. arXiv admin note: substantial text overlap with arXiv:1110.164

Disambiguating the ambiguity disadvantage effect: Behavioral and electrophysiological evidence for semantic competition

Semantic ambiguity has been shown to slow comprehension, although it is unclear whether this ambiguity disadvantage is attributable to competition in semantic activation or difficulties in response selection. We tested the two accounts by examining semantic relatedness decisions to homonyms, or words with multiple unrelated meanings (e.g., football/electric fan). Our behavioral results showed that the ambiguity disadvantage arises only when the different meanings of words are of comparable frequency, and are thus activated in parallel. Critically, this effect was observed regardless of response-selection difficulties, both when the different meanings triggered inconsistent responses on related trials (e.g., fan–breeze) and consistent responses on unrelated trials (e.g., fan–snake). Our electrophysiological results confirmed that this effect arises during semantic activation of the ambiguous word, indexed by the N400, not during response selection. Overall, the findings show that ambiguity resolution involves semantic competition and delineate why and when this competition arises