RevMexAA: Abstracts of Accepted Papers for Volume 47 Number 2


June 15, 2011

2011: December November October September August July June May April March February January


June 2011


V1898 Cygni: An interacting eclipsing binary in the vicinity of North America nebula

A. Dervişoǧlu,1 Ö. Çakirli,1,2 C. İbanoǧlu1 and E. Sipahi1

ahmetdervisoglu@mail.ege.edu.tr

Received: 2011 April 12

Accepted: 2011 June 12 (

)

Abstract: We present spectroscopic observations of the double-lined Algol type eclipsing binary V1898 Cyg. Analyses of the BV light curves and RVs led to determination of the fundamental stellar parameters of the V1898 Cyg’s components. The absolute parameters for the stars are derived as: M1 = 6.054 ± 0.037 M, M2 = 1.162 ± 0.011 M, R1 = 3.526 ± 0.009 R, R2 = 2.640 ± 0.010 R, T

eff˙1=18000±600 K, and T

eff˙2=6200±200 K. The residuals between the observed and computed times of mid-eclipses were analysed and a rate of the period change ∕P = 6.68 × 10-7 yr-1 was obtained and a mass transfer rate of 1.88 × 10-7 M in a year is estimated.We have calculated the distance to the system of V1898 Cyg as 501 ± 5 pc using the infrared JHK magnitudes and bolometric corrections for the primary star. The components of the system’s proper motions present some indications about membership of the North America nebula.



April 2011


On the stellar and baryonic mass fractions of central blue and red galaxies

A. Rodríguez-Puebla,1 V. Avila-Reese,1 C. Firmani,1,2 P. Colín,3

apuebla@astroscu.unam.mx

Received: 2011 January 21

Accepted: 2011 April 14 (

)

Abstract: Using the abundance matching technique, we infer the local stellar and baryonic mass-halo mass (Ms-Mh and Mb-Mh) relations separately for central blue and red galaxies (BGs and RGs). The observational inputs are the SDSS central BG and RG Stellar Mass Functions and the measured gas mass-Ms relations. For halos associated to central BGs, the distinct ΛCDM Halo Mass Function is used and set up to exclude: (i) the observed group/cluster mass function and (ii) halos with a central major merger at resdshifts z 0.8. For central RGs, the complement of this mass function to the total one is used. At Mh > 1011.5M , the Ms of RGs tend to be higher than those of BGs for a given Mh, the difference not being larger than 1.7. At Mh < 1011.5M , this trend is inverted. For BGs (RGs): (a) the maximum value of fs = Ms∕Mh is 0.021-0.009+0.016 (0.034 -0.015+0.026) and it is attained at log(Mh∕M) = 12.0 (=11.9); (b) fs Mh (fs Mh3) at the low-mass end while at the high-mass end, fs Mh-0.4 (f s Mh-0.6). The baryon mass fractions, fb = Mb∕Mh, of BGs and RGs reach maximum values of fb = 0.028-0.011+0.018 and f b = 0.034-0.014+0.025, respectively. At Mh < 1011.3M , the dependence of fb on Mh is much steeper for RGs than for BGs. We discuss on the differences found in the fs-Mh and fb-Mh relations between BGs and RGs in the light of semi-empirical galaxy evolution inferences.