- ID:
- ivo://CDS.VizieR/J/AJ/148/71
- Title:
- Spectroscopy and photometry of V501 Her
- Short Name:
- J/AJ/148/71
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- V501 Her is a well detached G3 eclipsing binary star with a period of 8.597687days for which we have determined very accurate light and radial-velocity curves using robotic telescopes. Results of these data indicate that the component stars have masses of 1.269+/-0.004 and 1.211+/-0.003 solar masses, radii of 2.001+/-0.003 and 1.511+/-0.003 solar radii, and temperatures of 5683+/-100 K and 5720+/-100K, respectively. Comparison with the Yonsei-Yale series of evolutionary models results in good agreement at an age of about 5.1Gyr for a somewhat metal-rich composition. Those models indicate that the more massive, larger, slightly cooler star is just beyond core hydrogen exhaustion while the less massive, smaller, slightly hotter star has not quite reached core hydrogen exhaustion. The orbit is not yet circularized, and the components are rotating at or near their pseudosynchronous velocities. The distance to the system is 420+/-30pc.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/AJ/150/190
- Title:
- Spectroscopy and Stromgren photometry of HR 1040
- Short Name:
- J/AJ/150/190
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A time-series analysis of spectroscopic and photometric observables of the A0 Ia supergiant HR 1040 has been performed, including equivalent widths, radial velocities, and Stromgren photometric indices. The data, obtained from 1993 through 2007, include 152 spectroscopic observations from the Ritter Observatory 1m telescope and 269 Stromgren photometric observations from the Four College Automated Photoelectric Telescope. Typical of late B- and early A-type supergiants, HR 1040 has a highly variable H{alpha} profile. The star was found to have an intermittent active phase marked by correlation between the H{alpha} absorption equivalent width and blue-edge radial velocity and by photospheric connections observed in correlations to equivalent width, second moment and radial velocity in SiII{lambda}{lambda}6347,6371. High-velocity absorption (HVA) events were observed only during this active phase. HVA events in the wind were preceded by photospheric activity, including SiII radial velocity oscillations 19-42 days prior to onset of an HVA event and correlated increases in SiII W_{lambda}_ and second moment from 13 to 23 days before the start of the HVA event. While increases in various line equivalent widths in the wind prior to HVA events have been reported in the past in other stars, our finding of precursors in enhanced radial velocity variations in the wind and at the photosphere is a new result.
- ID:
- ivo://CDS.VizieR/J/MNRAS/385/2210
- Title:
- Spectroscopy around lam Ori and sig Ori
- Short Name:
- J/MNRAS/385/2210
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have obtained multi-epoch, high-resolution spectroscopy of 218 candidate low-mass stars and brown dwarfs (BDs) in the young clusters around {lambda} Ori and {sigma} Ori. We find that 196 targets are cluster members based on their radial velocity, the equivalent width of their NaI 8200 lines and the spectral type from their TiO band strength. We have identified 11 new binary stars among the cluster members based on their variable radial velocity and an additional binary from the variation in its linewidth and shape. Of these, six are double-lined spectroscopic binaries (SB2) where the components of the binary are of comparable brightness. The others are single-lined binaries (SB1) in which the companion is faint or the spectra of the stars are blended. There are three narrow-lined SB1 binaries in our sample for which the companion is more than 2.5mag fainter than the primary.
- ID:
- ivo://CDS.VizieR/J/A+A/540/A27
- Title:
- Spectroscopy in Galactic globular clusters
- Short Name:
- J/A+A/540/A27
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Well determined radial velocities and abundances are essential for analyzing the properties of the Globular Cluster system of the Milky Way. However more than 50% of these clusters have no spectroscopic measure of their metallicity. In this context, this work provides new radial velocities and abundances for twenty Milky Way globular clusters which lack or have poorly known values for these quantities. The radial velocities and abundances are derived from spectra obtained at the CaII triplet using the FORS2 imager and spectrograph at the VLT, calibrated with spectra of red giants in a number of clusters with well determined abundances. For about half of the clusters in our sample we present signifiant revisions of the existing velocities or abundances, or both.
- ID:
- ivo://CDS.VizieR/J/AJ/132/1796
- Title:
- Spectroscopy in nearby group cores
- Short Name:
- J/AJ/132/1796
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We used V and I CCD photometry to search for low surface brightness dwarf galaxies in the central (<0.5h^-1^Mpc) region of the groups NGC 6868, NGC 5846, HCG 42, and the poor cluster IC 4765. We used the exponential profile fit parameters to identify 80 low surface brightness dwarf galaxy candidates with 17mag<V<22mag (-16.7>MV>-11.4), V-I<1.5mag, {mu}_0_>22.5Vmag/arcsec^2^, h>1.5", and diameters larger than 1.2h^-1^kpc. Twenty of these galaxies are extended low surface brightness galaxies that were detected only on smoothed images, after masking all high surface brightness objects. The completeness in the sample detection is ~80% for V~<20 and 22.5Vmag/arcsec^2^<{mu}_0_<24.5Vmag/arcsec^2^. For galaxies with V>20mag and {mu}_0_>24.5Vmag/arcsec^2^, the completeness is below 50% but increases to ~80% when we search for galaxies in smoothed images.
- ID:
- ivo://CDS.VizieR/J/AJ/148/83
- Title:
- Spectroscopy in NGC 2360, NGC 3680, and NGC 5822
- Short Name:
- J/AJ/148/83
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Binary stars in open clusters are very useful targets in constraining the nucleosynthesis process. The luminosities of the stars are known because the distances of the clusters are also known, so chemical peculiarities can be linked directly to the evolutionary status of a star. In addition, binary stars offer the opportunity to verify a relationship between them and the straggler population in both globular and open clusters. We carried out a detailed spectroscopic analysis to derive the atmospheric parameters for 16 red giants in binary systems and the chemical composition of 11 of them in the open clusters NGC 2360, NGC 3680, and NGC 5822. We obtained abundances of C, N, O, Na, Mg, Al, Ca, Si, Ti, Ni, Cr, Y, Zr, La, Ce, and Nd. The atmospheric parameters of the studied stars and their chemical abundances were determined using high-resolution optical spectroscopy. We employ the local thermodynamic equilibrium model atmospheres of Kurucz and the spectral analysis code MOOG. The abundances of the light elements were derived using the spectral synthesis technique. We found that the stars NGC 2360-92 and 96, NGC 3680-34, and NGC 5822-4 and 312 are yellow straggler stars. We show that the spectra of NGC 5822-4 and 312 present evidence of contamination by an A-type star as a secondary star. For the other yellow stragglers, evidence of contamination is given by the broad wings of the H{alpha}. Detection of yellow straggler stars is important because the observed number can be compared with the number predicted by simulations of binary stellar evolution in open clusters. We also found that the other binary stars are not s-process enriched, which may suggest that in these binaries the secondary star is probably a faint main-sequence object. The lack of any s-process enrichment is very useful in setting constraints for the number of white dwarfs in the open cluster, a subject that is related to the birthrate of these kinds of stars in open clusters and also to the age of a cluster. Finally, rotational velocities were also determined and their values were compared with those already determined for field giant stars.
- ID:
- ivo://CDS.VizieR/J/AJ/129/363
- Title:
- Spectroscopy in Orion Nebula Cluster
- Short Name:
- J/AJ/129/363
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results from high-resolution spectra of 237 stars in the Orion Nebula cluster (ONC) obtained during two engineering runs with the Hectochelle multifiber echelle spectrograph on the 6.5m MMT. The ONC is the nearest populous young (age ~1Myr) cluster and is therefore an important object for studies of the evolution of protoplanetary disks. Using the high spectral resolution of Hectochelle, we are able to distinguish stellar accretion and wind emission-line profiles from nebular emission lines and identify accreting members of the cluster from H{alpha} profiles with greater accuracy than previously possible. We find 15 new members on the basis of Li {lambda}6707 absorption and H{alpha} emission. Line profiles of H{alpha} of some objects that are not too contaminated by nebular emission show features characteristic of mass inflow and ejection. We also present rotational velocities as part of an initial investigation into angular momentum evolution of very young stars, confirming a difference between classical T Tauri stars and weak-line T Tauri stars that had been found from period analysis. Finally, we present an initial study of the radial velocity dispersion of the brighter stars in the central cluster. The very small dispersion derived, 1.8km/s, is in good agreement with estimates from proper motions.
- ID:
- ivo://CDS.VizieR/J/ApJ/661/1119
- Title:
- Spectroscopy in the 25 Ori group
- Short Name:
- J/ApJ/661/1119
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report here on the photometric and kinematic properties of a well-defined group of nearly 200 low-mass pre-main-sequence stars, concentrated within ~1{deg} of the early-B star 25 Ori, in the Orion OB1a subassociation. We refer to this stellar aggregate as the 25 Orionis group. The group also harbors the Herbig Ae/Be star V346 Ori and a dozen other early-type stars with photometry, parallaxes, and some with IR excess emission, indicative of group membership.
- ID:
- ivo://CDS.VizieR/J/AJ/159/24
- Title:
- Spectroscopy & Kepler data of the EB star V404 Lyr
- Short Name:
- J/AJ/159/24
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first high-resolution spectra for the eclipsing binary V404Lyr showing {gamma}Dor pulsations, which we use to study its absolute properties. By fitting models to the disentangling spectrum of the primary star, we found that it has an effective temperature of T_eff,1_=7330{+/-}150K and a rotational velocity of v_1_sini=148{+/-}18km/s. The simultaneous analysis of our double-lined radial velocities and the pulsation-subtracted Kepler data gives us accurate stellar and system parameters of V404Lyr. The masses, radii, and luminosities are M1=2.17{+/-}0.06M_{sun}_, R1=1.91{+/-}0.02R_{sun}_, and L1=9.4{+/-}0.8L_{sun}_ for the primary, and M2=1.42{+/-}0.04M_{sun}_, R2=1.79{+/-}0.02R_{sun}_, and L2=2.9{+/-}0.2L_{sun}_ for the secondary. The tertiary component orbiting the eclipsing pair has a mass of M_3b_=0.71{+/-}0.15M_{sun}_ in an orbit of P_3b_=642{+/-}3d, e_3b_=0.21{+/-}0.04, and a_3b_=509{+/-}2R_{sun}_. The third light of l_3_=4.1{+/-}0.2% could be partly attributable to the K-type circumbinary object. By applying a multiple frequency analysis to the eclipse-subtracted light residuals, we detected 45 frequencies with signal-to-noise amplitude ratios larger than 4.0. Identified as independent pulsation modes, seven frequencies (f_1_-f_6_, f_9_), their new pulsation constants, and the location in the Hertzsprung-Russell diagram indicate that the pulsating primary is a {gamma}Dor-type variable star.
- ID:
- ivo://CDS.VizieR/J/ApJ/834/9
- Title:
- Spectroscopy obs. of LeoA, Aqr & Sgr dwarf gal.
- Short Name:
- J/ApJ/834/9
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present Keck/DEIMOS spectroscopy of individual stars in the relatively isolated Local Group dwarf galaxies Leo A, Aquarius, and the Sagittarius dwarf irregular galaxy. The three galaxies-but especially Leo A and Aquarius-share in common delayed star formation histories (SFHs) relative to many other isolated dwarf galaxies. The stars in all three galaxies are supported by dispersion. We found no evidence of stellar velocity structure, even for Aquarius, which has rotating HI gas. The velocity dispersions indicate that all three galaxies are dark-matter-dominated, with dark-to-baryonic mass ratios ranging from 4.4_-0.8_^+1.0^ (SagDIG) to 9.6_-1.8_^+2.5^ (Aquarius). Leo A and SagDIG have lower stellar metallicities than Aquarius, and they also have higher gas fractions, both of which would be expected if Aquarius were further along in its chemical evolution. The metallicity distribution of Leo A is inconsistent with a closed or leaky box model of chemical evolution, suggesting that the galaxy was pre-enriched or acquired external gas during star formation. The metallicities of stars increased steadily for all three galaxies, but possibly at different rates. The [{alpha}/Fe] ratios at a given [Fe/H] are lower than that of the Sculptor dwarf spheroidal galaxy, which indicates more extended SFHs than Sculptor, consistent with photometrically derived SFHs. Overall, the bulk kinematic and chemical properties for the late-forming dwarf galaxies do not diverge significantly from those of less delayed dwarf galaxies, including dwarf spheroidal galaxies.
