Related papers: A slitless spectroscopic survey for Halpha emissio…
Using a sample of 299 Ha-selected galaxies at z~0.8, we study the relationship between galaxy stellar mass, gas-phase metallicity, and star formation rate (SFR), and compare to previous results. We use deep optical spectra obtained with the…
We present multiple epochs of H-alpha spectroscopy for 47 members of the open cluster NGC 3766 to investigate the long term variability of its Be stars. Sixteen of the stars in this sample are Be stars, including one new discovery. Of…
We study the multiple populations of $\omega$ Cen by using the abundances of Fe, C, N, O, Mg, Al, Si, K, Ca, and Ce from the high-resolution, high signal-to-noise (S/N$>$70) spectra of 982 red giant stars observed by the SDSS-IV/APOGEE-2…
The combination of photometry, spectroscopy and spectropolarimetry of the chemically peculiar stars often aims to study the complex physical phenomena such as stellar pulsation, chemical inhomogeneity, magnetic field and their interplay…
We present a deep survey of Halpha emission-line stars in the M42 region using wide-field objective prism films. A total of 1699 Halpha emission-line stars were identified, of which 1025 were previously unknown, within an area of 5.5 x 5.5…
The stellar mass-luminosity relation is poorly constrained by observations for high mass stars. We describe our program to find eclipsing massive binaries in the Magellanic Clouds using photometry of regions rich in massive stars, and our…
The Magellanic Clouds are a local laboratory for understanding the evolution and properties of dwarf irregular galaxies. To reveal the extended structure and interaction history of the Magellanic Clouds we have undertaken a large-scale…
We report on the strengths of three spectral indicators - Mg_2, Hbeta, and Hn/Fe - in the integrated light of a sample of 100 field and cluster E/S0 galaxies. The measured indices are sensitive to age and/or and metallicity variations…
This is a catalogue of approximately 70 X-ray emitting binary systems in the Small Magellanic Cloud (SMC) that contain a Be star as the mass donor in the system and a clear X-ray pulse signature from a neutron star. The systems are…
We have studied the optical spectra of a sample of 31 O- and early B-type stars in the Small Magellanic Cloud, 21 of which are associated with the young massive cluster NGC 346. Stellar parameters are determined using an automated fitting…
We study the evolutionary and physical properties of evolved O stars in the Small Magellanic Cloud (SMC), with a special focus on their surface abundances to investigate the efficiency of rotational mixing as a function of age, rotation and…
At low metallicity the B-type stars rotate faster than at higher metallicity, typically in the SMC. As a consequence, it was expected a larger number of fast rotators in the SMC than in the Galaxy, in particular more Be/Oe stars. With the…
We present the results of a spectroscopic investigation of two novel variable bright blue stars in the SMC, OGLE004336.91-732637.7 (SMC-SC3) and the periodically occulted star OGLE004633.76-731204.3 (SMC-SC4), whose photometric properties…
We present a photometric survey aimed to characterize the Be star population of young open clusters. It is found that in these clusters early-type Be stars are more frequent than in the galactic field, and late-type Be stars are scarce or…
Be stars are main-sequence massive stars with emission features in their spectrum, which originates in circumstellar gaseous discs. Even though the viscous decretion disc (VDD) model can satisfactorily explain most observations, two…
Aims. We attempt to determine if a dependency on spectral subtype or vsini exists for stars undergoing phase-changes between B and Be states, as well as for those stars exhibiting variability in H{\alpha} emission. Methods. We analyse the…
High resolution spectra of 110 selected red giant stars in the globular cluster M15 (NGC 7078) were obtained with Hectochelle at the MMT telescope in 2005 May, 2006 May, and 2006 October. Echelle orders containing Halpha and Ca H & K are…
No classical Oe/Be stars with spectral type earlier than O7.5e have been identified to date in the Milky Way (MW). This is consistent with the decretion disk model because strong stellar winds cause early-type O stars to lose angular…
We present new high and low resolution spectroscopic and photometric data of nine members of the young association CMa R1. All the stars have circumstellar dust at some distance as could be expected from their association with reflection…
We present 3.5m Apache Point Observatory second-epoch spectra of four low-metallicity emission-line dwarf galaxies discovered serendipitously in the Data Release 5 of the Sloan Digital Sky Survey (SDSS) to have extraordinary large broad…