Search

Start Over Subject spectroscopy
1761. New FeII energy levels from stellar spectra
ID:
ivo://CDS.VizieR/J/A+A/520/A57
Title:
New FeII energy levels from stellar spectra
Short Name:
J/A+A/520/A57
Date:
21 Oct 2021
Publisher:
CDS
Description:
The spectra of B-type and early A-type stars show numerous unidentified lines in the whole optical range, especially in the 5100-5400{AA} interval. Because FeII transitions to high energy levels should be observed in this region, we used semiempirical predicted wavelengths and gf-values of FeII to identify unknown lines. Semiempirical line data for FeII computed by Kurucz are used to synthesize the spectrum of the slow-rotating, Fe - overabundant CP star HR6000.
1762. New FeI level energies from stellar spectra
ID:
ivo://CDS.VizieR/J/ApJS/216/1
Title:
New FeI level energies from stellar spectra
Short Name:
J/ApJS/216/1
Date:
21 Oct 2021
Publisher:
CDS
Description:
The spectrum of the Fe I atom is critical to many areas of astrophysics and beyond. Measurements of the energies of its high-lying levels remain woefully incomplete, however, despite extensive laboratory and solar analysis. In this work, we use high-resolution archival absorption-line ultraviolet and optical spectra of stars whose warm temperatures favor moderate Fe I excitation. We derive the energy for a particular upper level in Kurucz's semiempirical calculations by adopting a trial value that yields the same wavelength for a given line predicted to be about as strong as that of a strong unidentified spectral line observed in the stellar spectra, then checking the new wavelengths of other strong predicted transitions that share the same upper level for coincidence with other strong observed unidentified lines. To date, this analysis has provided the upper energies of 66 Fe I levels. Many new energy levels are higher than those accessible to laboratory experiments; several exceed the Fe I ionization energy. These levels provide new identifications for over 2000 potentially detectable lines. Almost all of the new levels of odd parity include UV lines that were detected but unclassified in laboratory Fe I absorption spectra, providing an external check on the energy values. We motivate and present the procedure, provide the resulting new energy levels and their uncertainties, list all the potentially detectable UV and optical new Fe I line identifications and their gf values, point out new lines of astrophysical interest, and discuss the prospects for additional Fe I energy level determinations.
1763. New FeI level energies from stellar spectra. II.
ID:
ivo://CDS.VizieR/J/ApJS/229/23
Title:
New FeI level energies from stellar spectra. II.
Short Name:
J/ApJS/229/23
Date:
21 Oct 2021
Publisher:
CDS
Description:
The Fe I spectrum is critical to many areas of astrophysics, yet many of the high-lying levels remain uncharacterized. To remedy this deficiency, Peterson & Kurucz (2015, J/ApJS/216/1) identified Fe I lines in archival ultraviolet and optical spectra of metal-poor stars, whose warm temperatures favor moderate Fe I excitation. Sixty-five new levels were recovered, with 1500 detectable lines, including several bound levels in the ionization continuum of Fe I. Here, we extend the previous work by identifying 59 additional levels, with 1400 detectable lines, by incorporating new high-resolution UV spectra of warm metal-poor stars recently obtained by the Hubble Space Telescope Imaging Spectrograph. We provide gf values for these transitions, both computed as well as adjusted to fit the stellar spectra. We also expand our spectral calculations to the infrared, confirming three levels by matching high-quality spectra of the Sun and two cool stars in the H-band. The predicted gf values suggest that an additional 3700 Fe I lines should be detectable in existing solar infrared spectra. Extending the empirical line identification work to the infrared would help confirm additional Fe I levels, as would new high-resolution UV spectra of metal-poor turnoff stars below 1900{AA}.
1764. New ground-state measurements of ethyl cyanide
ID:
ivo://CDS.VizieR/J/ApJS/184/133
Title:
New ground-state measurements of ethyl cyanide
Short Name:
J/ApJS/184/133
Date:
21 Oct 2021
Publisher:
CDS
Description:
The spectrum of ethyl cyanide, or propionitrile (CH_3_CH_2_CN), has been repeatedly observed in the interstellar medium with large column densities and surprisingly high temperatures in hot core sources. The construction of new, more sensitive, observatories accessing higher frequencies such as Herschel, ALMA, and SOFIA have made it important to extend the laboratory data for ethyl cyanide to coincide with the capabilities of the new instruments. We report extensions of the laboratory measurements of the rotational spectrum of ethyl cyanide in its ground vibrational state to 1.6THz. A global analysis of the ground state, which includes all of the previous data and 3356 newly assigned transitions, has been fitted to within experimental error to J=132, K=36, using both Watson A-reduced and Watson S-reduced Hamiltonians.
1765. New high proper motion stars in the northern sky
ID:
ivo://CDS.VizieR/J/AJ/125/1598
Title:
New high proper motion stars in the northern sky
Short Name:
J/AJ/125/1598
Date:
21 Oct 2021
Publisher:
CDS
Description:
We define an enhanced spectral classification scheme for M dwarf stars and use it to derive spectral classification of 104 northern stars with proper motions larger than 0.5"/yr that we discovered in a survey of high proper motion stars at low Galactic latitudes. The final tally is as follows: 54 M dwarfs, 25 sdK and sdM subdwarfs, 14 esdK and esdM extreme subdwarfs, and 11 DA and DC white dwarfs. Among the most interesting cases, we find one star to be the coolest subdwarf ever reported (LSR 2036+5059, with spectral type sdM7.5), a new M9.0 dwarf only about 6 pc distant (LSR 1835+3259), and a new M6.5 dwarf only 7 pc from the Sun (LSR 2124+4003). Spectroscopic distances suggests that 27 of the M dwarfs, three of the white dwarfs, and one of the subdwarfs (LSR 2036+5059) are within 25 pc of the Sun, making them excellent candidates for inclusion in the solar neighborhood census. Estimated sky-projected velocities suggest that most of our subdwarfs and extreme subdwarfs have halo kinematics. We find that several white dwarfs and nonmetal-poor M dwarfs also have kinematics consistent with the halo, and we briefly discuss their possible origin.
1766. New MnII energy levels
ID:
ivo://CDS.VizieR/J/A+A/580/A10
Title:
New MnII energy levels
Short Name:
J/A+A/580/A10
Date:
21 Oct 2021
Publisher:
CDS
Description:
The NIST database lists several MnI lines that were observed in the laboratory but not classified. They cannot be used in spectrum synthesis because their atomic line data are unknown. These lines are concentrated in the 2380-2700{AA} interval. We aimed to assign energy levels and loggf values to these lines. Semi-empirical line data for MnII computed by Kurucz were used to synthesize the ultraviolet spectrum of the slow-rotating, HgMn star HD 175640. The spectrum was compared with the high-resolution spectrum observed with the HST-STIS equipment. A UVES spectrum covering the 3050-10000{AA} region was also examined.
1767. New sample of low-mass black holes in AGN
ID:
ivo://CDS.VizieR/J/ApJ/670/92
Title:
New sample of low-mass black holes in AGN
Short Name:
J/ApJ/670/92
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present an expanded sample of low-mass black holes (BHs) found in galactic nuclei. Using standard virial mass techniques to estimate BH masses, we select from the Fourth Data Release of the Sloan Digital Sky Survey all broad-line active galaxies with masses <2x10^6^M_{sun}_ BHs in this mass regime provide unique tests of the relationship between BHs and galaxies, since their late-type galaxy hosts do not necessarily contain classical bulges. Furthermore, they provide observational analogs of primordial seed BHs and are expected, when merging, to provide strong gravitational signals for future detectors such as LISA. From our preliminary sample of 19, we have increased the total sample by an order of magnitude to 174, as well as an additional 55 (less secure) candidates.
1768. New Sample of OH/IR stars
ID:
ivo://CDS.VizieR/J/A+AS/128/35
Title:
New Sample of OH/IR stars
Short Name:
J/A+AS/128/35
Date:
21 Oct 2021
Publisher:
CDS
Description:
Tables 2 and 3 present the positional and kinematic, and physical data for OH/IR stars found within 37 arcmin of the Galactic center (Sgr A*) respectively.
1769. New satellites of the LMC search
ID:
ivo://CDS.VizieR/J/A+A/623/A129
Title:
New satellites of the LMC search
Short Name:
J/A+A/623/A129
Date:
21 Oct 2021
Publisher:
CDS
Description:
A wealth of tiny galactic systems populates the surroundings of the Milky Way. However, some of these objects might have originated as former satellites of the Magellanic Clouds, in particular of the Large Magellanic Cloud (LMC). Examples of the importance of understanding how many systems are genuine satellites of the Milky Way or the LMC are the implications that the number and luminosity-mass function of satellites around hosts of different mass have for dark matter theories and the treatment of baryonic physics in simulations of structure formation. Here we aim at deriving the bulk motions and estimates of the internal velocity dispersion and metallicity properties in four recently discovered distant southern dwarf galaxy candidates, Columba I, Reticulum III, Phoenix II, and Horologium II. We combined Gaia DR2 astrometric measurements, photometry, and new FLAMES/GIRAFFE intermediate-resolution spectroscopic data in the region of the near-IR CaII triplet lines; this combination is essential for finding potential member stars in these low-luminosity systems. We find very likely member stars in all four satellites and are able to determine (or place limits on) the bulk motions and average internal properties of the systems. The systems are found to be very metal poor, in agreement with dwarf galaxies and dwarf galaxy candidates of similar luminosity. Of these four objects, we can only firmly place Phoenix II in the category of dwarf galaxies because of its resolved high velocity dispersion (9.5^+6.8^_-4.4_km/s) and intrinsic metallicity spread (0.33dex). For Columba I we also measure a clear metallicity spread. The orbital pole of Phoenix II is well constrained and close to that of the LMC, suggesting a prior association. The uncertainty on the orbital poles of the other systems is currently very large, so that an association cannot be excluded, except for Columba I. Using the numbers of potential former satellites of the LMC identified here and in the literature, we obtain for the LMC a dark matter mass of M_200_=1.9^+1.3^_-0.9_x10^11^M_{sun}_
1770. New spectral types for Tycho2 stars
ID:
ivo://CDS.VizieR/J/PAZh/34/21
Title:
New spectral types for Tycho2 stars
Short Name:
J/PAZh/34/21
Date:
21 Oct 2021
Publisher:
CDS
Description:
We compare the spectroscopic and trigonometric parallaxes of common stars from the Tycho-2 Spectral Type and Hipparcos Catalogues. This comparison has revealed that the distance estimations for the overwhelming majority of stars by both methods yield very similar results. However, there is a small fraction of stars for which the distance estimates differences.

Limit your search

more »

more »

more »

more »

more »