Direct imaging provides a steady flow of newly discovered giant planets and brown dwarf companions. These multi-object systems can provide information about the formation of low-mass companions in wide orbits and/or speculate about possible migration scenarios. The accurate classification of the companions is crucial for testing formation pathways. In this work we characterize further the recently discovered candidate for a planetary-mass companion CS Cha b and determine if it is still accreting. MUSE is a 4-laser-adaptive-optics-assisted medium-resolution integral-field spectrograph in the optical part of the spectrum. We observed the CS Cha system to obtain the first spectrum of CS Cha b. The companion is characterized by modelling both the spectrum from 6300{AA}, to 9300{AA}, and the photometry using archival data from the visible to the near-infrared. We find evidence of accretion and outflow signatures in H{alpha} and OI emission. The atmospheric models with the highest likelihood indicate an effective temperature of 3450+/-50K with a logg of 3.6+/-0.5dex. Based on evolutionary models, we find that the majority of the object is obscured. We determine the mass of the faint companion with several methods to be between 0.07 Msun and 0.71M_{sun}_ with an accretion rate of dM/dt=4x10^-11^+/-0.4x10^-11^M_{sun}_/yr. Our results show that CS Cha B is most likely a mid M-type star that is obscured by a highly inclined disk, which has led to its previous classification by broadband NIR photometry as a planetary-mass companion. This shows that it is important and necessary to observe over a broad spectral range to constrain the nature of faint companions.
The Type Ia supernova (SN Ia) LSQ14fmg exhibits exaggerated properties that may help to reveal the origin of the "super-Chandrasekhar" (or 03fg-like) group. The optical spectrum is typical of a 03fg-like SNIa, but the light curves are unlike those of any SNe Ia observed. The light curves of LSQ14fmg rise extremely slowly. At -23 rest-frame days relative to B-band maximum, LSQ14fmg is already brighter than M_V_=-19mag before host extinction correction. The observed color curves show a flat evolution from the earliest observation to approximately 1 week after maximum. The near-infrared light curves peak brighter than -20.5mag in the J and H bands, far more luminous than any 03fg-like SNe Ia with near-infrared observations. At 1 month past maximum, the optical light curves decline rapidly. The early, slow rise and flat color evolution are interpreted to result from an additional excess flux from a power source other than the radioactive decay of the synthesized 56Ni. The excess flux matches the interaction with a typical superwind of an asymptotic giant branch (AGB) star in density structure, mass-loss rate, and duration. The rapid decline starting at around 1 month past B-band maximum may be an indication of rapid cooling by active carbon monoxide (CO) formation, which requires a low-temperature and high-density environment. These peculiarities point to an AGB progenitor near the end of its evolution and the core degenerate scenario as the likely explosion mechanism for LSQ14fmg.
Quasars can be used as a complementary tool to SN Ia to probe the distribution of dark energy in the Universe by measuring the time delay of the emission line with respect to the continuum. The understanding of the MgII emission line structure is important for cosmological application and for the black hole mass measurements of intermediate redshift quasars. Knowing the shape of MgII line and its variability allows for identification which part of the line should be used to measure the time delay and the black hole mass. We thus aim at determining the structure and the variability of the MgII line, as well as the underlying FeII pseudo-continuum. We performed five spectroscopic observations of a quasar CTS C30.10 (z=0.9000) with the SALT telescope between December 2012 and March 2014, and we studied the variations in the spectral shape in the 2700{AA}-2900{AA} rest frame. We show that the MgII line in this source consists of two kinematic components, which makes the source representative of type B quasars. Both components were modeled well with a Lorentzian shape, and they vary in a similar way. The FeII contribution seems to be related only to the first (blue) MgII component. Broad band spectral fitting instead favor the use of the whole line profile. The contribution of the narrow line region to MgII is very low, below 2%. The MgII variability is lower than the variability of the continuum, which is consistent with the simple reprocessing scenario. The variability level of CTS C30.10 and the measurement accuracy of the line and continuum is high enough to expect that further monitoring will allow the time delay between the MgII line and continuum to be measured.
We present the CIDAUCMYale (Centro de Investigaciones de Astronomia, Universidad Complutense de Madrid, and Yale University) Survey (CUYS) for H{alpha}+[NII] 6549, 6584{AA} emission-line galaxies (ELGs) using objective-prism spectra. The most important properties of a catalogue with 427 entries and significant subsets are analysed. The complete sample contains 183 statistically confirmed ELGs in a sky area of 151deg^2^ and redshift up to 0.14. We determine the parameters of the H{alpha} luminosity function using the H{alpha}+[NII] flux directly measured on the ELG spectra in this sample, and the star formation rate density derived is in agreement with values reported in the literature.
This paper completes the series of cataclysmic variables (CVs) identified from the Sloan Digital Sky Survey (SDSS) I/II. The coordinates, magnitudes, and spectra of 33 CVs are presented. Among the 33 are eight systems known prior to SDSS (CT Ser, DO Leo, HK Leo, IR Com, V849 Her, V405 Peg, PG1230+226, and HS0943+1404), as well as nine objects recently found through various photometric surveys. Among the systems identified since the SDSS are two polar candidates, two intermediate polar candidates, and one candidate for containing a pulsating white dwarf. Our follow-up data have confirmed a polar candidate from Paper VII and determined tentative periods for three of the newly identified CVs. A complete summary table of the 285 CVs with spectra from SDSS I/II is presented as well as a link to an online table of all known CVs from both photometry and spectroscopy that will continue to be updated as future data appear.
HC_3_N is a ubiquitous molecule in interstellar environments, from external galaxies to Galactic interstellar clouds, star-forming regions, and planetary atmospheres. Observations of its rotational and vibrational transitions provide important information on the physical and chemical structures of the above environments. We present the most complete global analysis of the spectroscopic data of HC_3_N. We recorded the high-resolution infrared spectrum from 450 to 1350cm^-1^, a region dominated by the intense {nu}_5_ and {nu}_6_ fundamental bands, located at 660 and 500cm^-1^, respectively, and their associated hot bands. Pure rotational transitions in the ground and vibrationally excited states were recorded in the millimeter and submillimeter regions in order to extend the frequency range so far considered in previous investigations. All of the transitions from the literature and from this work involving energy levels lower than 1000cm^-1^ were fitted together to an effective Hamiltonian. Because of the presence of various anharmonic resonances, the Hamiltonian includes a number of interaction constants, in addition to the conventional rotational and vibrational l-type resonance terms. The data set contains about 3400 ro-vibrational lines of 13 bands and some 1500 pure rotational lines belonging to 12 vibrational states. More than 120 spectroscopic constants were determined directly from the fit, without any assumption deduced from theoretical calculations or comparisons with similar molecules. An extensive list of highly accurate rest frequencies was produced to assist astronomical searches and data interpretation. These improved data enabled a refined analysis of the ALMA observations toward Sgr B2(N2).
Cygnus OB2 provides a unique insight into the high-mass stellar content in one of the largest groups of young massive stars in our Galaxy. Although several studies of its massive population have been carried out over the last decades, an extensive spectroscopic study of the whole known O-star population in the association is still lacking. In this work, we created the most complete spectroscopic census of O stars carried out so far in Cygnus OB2 using already existing and new spectroscopy. We present the spectra for 78 O-type stars, from which we identify new binary systems, obtain the distribution of rotational velocities, and determine the main stellar parameters for all the stars in the region that have not been detected as double-line spectroscopic binaries. We also derive radii, luminosities, and masses for those stars with reliable Gaia astrometry, in addition to creating the Hertzsprung- Russell Diagram to interpret the evolutionary status of the association. This work has shown the improvement reached when using accurate spectroscopic parameters and astrometry for the interpretation of the evolutionary status of a population, revealing, in the case of Cygnus OB2, at least two star-forming bursts at ~3 and ~5Myr. We find an apparent deficit of very fast rotators in the distribution of rotational velocities. The inspection of the dynamical distribution of the sample has allowed us to identify nine O stars with peculiar proper motions and discuss a possible dynamical ejection scenario or past supernova explosions in the region.
We present four epochs, A, B, C and D, of resolution ({lambda}/{delta}{lambda}) = 1200, 2.12 micron spectroscopy of the peculiar X-ray binary Cygnus X-3. About a half dozen spectra taken with resolution 900, and at 1.62 micron are also included. These data were obtained using the FSpec near-infrared spectrometer (Williams, D., Thompson, C.L., Rieke, G.H., Montgomery, E. 1993, Proc. SPIE 1308, 482) on the Multiple Mirror Telescope (MMT). The MMT is located at an elevation of 2600 m at the top of Mt. Hopkins in southern Arizona and is jointly operated by the Smithsonian Astrophysics Observatory and the University of Arizona. The spectra are stored as ascii files, listing wavelength in Angstroms and relative flux. Each file contains a five line header, giving the UT, Heliocentric Julian date and phase of the X-ray system at the start of the integration, followed by the data points. Additional information about the spectra can be obtained in the paper.
We present a new study of the eclipsing cataclysmic variable CzeV404 Her (Porb=0.098d) located in the period gap. This report aims to determine the object's origin, system parameters and probe the system's accretion flow structure. We conducted simultaneous time-resolved photometric and spectroscopic observations of CzeV404 Her. We applied our light curve modeling techniques and the Doppler tomography method to determine the system parameters and analyse the structure of the accretion disk. We found that the system has a massive white dwarf M_WD_=1.00(2)M_{sun}_, a mass ratio of q=0.16, and a relatively hot secondary with an effective temperature T_2_=4100(50)K. The system inclination is 78{deg}. The accretion disk spreads out to the tidal limitation radius and has an extended hot spot/line region. The hot spot/line is hotter than the rest of the disk's outer part in quiescence or intermediate state but does not stand out completely from the disk flux in (super)outbursts. We claim that this object represents a link between two distinct classes of SU UMa-type and SW Sex-type cataclysmic variables. The accretion flow structure in the disk corresponds to the SW Sex systems, but the physical conditions inside the disk passed into behaviors of SU UMa-type objects.
We present the results of a survey of damped (DLA, logN(HI)>20.3) and sub-damped Lyman-{alpha} systems (19.5<logN(HI)<20.3) at z>2.55 along the lines-of-sight to 77 quasars with emission redshifts in the range 4<z_em_<6.3. Intermediate resolution (R~4300) spectra were obtained with the Echellette Spectrograph and Imager (ESI) mounted on the Keck telescope. A total of 100 systems with logN(HI)>19.5 were detected of which 40 systems are damped Lyman-{alpha} systems for an absorption length of {Delta}X= 378. About half of the lines of sight of this homogeneous survey have never been investigated for DLAs.
