scholarly journals MWC 314 – A new galactic B[e] supergiant

1994 ◽  
Vol 162 ◽  
pp. 396-397
Author(s):  
Anatoly S. Miroshnichenko
Keyword(s):  
Radio Source ◽  
Spectral Type ◽  
Emission Lines ◽  
Spectral Features ◽  
Late Type ◽  
Symbiotic System ◽  
Strong Emission ◽  
Normal Star ◽  
Late Type Star ◽  
Gaseous Envelope

We present a new study of MWC 314 = BD +14°3887 – a poorly investigated object with strong emission lines and IR excesses. Merrill (1927) payed attention to it because of the presence of hydrogen and Fe II emissions in its spectrum. Swensson (1942) also detected interstellar lines H and K CaII and 4430 Å band, Balmer emissions from Hα to H8, NaI 5890 and 5896 Å emissions and estimated its spectral type as gG2-3 or dG4-5 from the SED in continuum, and B2 from the excitation degree. Photospheric lines and spectral features of late-type stars were not observed. Allen (1973) noted that the object's SED corresponds to that of a late-type star but it might be a symbiotic system or a reddened normal star. The IRAS fluxes were obtained only at 12 and 25 μm. The object is unknown as a radio source. From this we can conclude that this system consists of, at least, a hot star surrounded by a gaseous envelope.

scholarly journals Molecular Bands in the 1.1-1.4 μm Spectra of M-S-C stars

1989 ◽  
Vol 106 ◽  
pp. 61-61
Author(s):  
Kenneth H. Hinkle ◽  
David L. Lambert ◽  
Robert F. Wing
Keyword(s):  
Spectral Type ◽  
Short Wavelength ◽  
Near Infrared ◽  
Laboratory Work ◽  
Band Spectrum ◽  
Spectral Features ◽  
Late Type ◽  
Minimum Light ◽  
Considerable Range

Spectra are presented in the J band (7400 to 9700 cm-1) for four Miras ranging in spectral type from M through C. All the program stars have been observed near minimum light. The program stars cover a considerable range in C/0 and the spectral features exhibit a progression as a function of C/0. The S-type stars contain strong bands not previously reported. Especially striking are two sets of triple-headed bands in the J-band spectrum of the S-type Mira R And. The bandheads, which are degraded to longer wavelengths, are at 7877, 7957, 8030 cm-1 and 8379, 8459, 8530 cm-1. The former triplet, which is the stronger of the two, also is present in the mild S star × Cyg but not in the M star R Cas. Additional heads are found in R And at 7477 cm-1, near the short wavelength edge of strong telluric absorption, and at 8968, 9031, 9063 cm-1. The bands are identified as the Δv = -1, 0, 1, and 2 sequences of a predicted (3II-3Δ) transition of ZrS. Additional conspicuous features in the spectra of × Cyg and R Cas are identified with V0, TiO, and H20 bands. These observations provide additional evidence that ZrS is responsible for the majority of the Keenan-Wing bands in the near infrared (0.7-1.1 μ). With additional laboratory work, the ZrS bands will provide an opportunity to measure sulfur abundances in late-type stellar photospheres.

scholarly journals Relationships of the Active Nucleus, Galaxy, and Environment

1989 ◽  
Vol 134 ◽  
pp. 425-444
Author(s):  
K. J. Fricke ◽  
W. Kollatschny
Keyword(s):  
Radio Source ◽  
Intergalactic Medium ◽  
Emission Lines ◽  
Host Galaxies ◽  
Active Nucleus ◽  
Strong Emission ◽  
Nuclear Activity ◽  
Isolated Galaxies ◽  
First Time

35 years ago Baade and Minkowski (1954) suggested that a galaxy collision - diagnosed from the peculiar appearance of the parent object and its strong emission lines - is responsible for the strong radio-source CygA. This was the first time that gravitational interactions between galaxies were suggested to trigger nuclear activity. Over the following decades after the detection of the quasars and the gradual realization that quasars, comparable to the Seyfert phenomenon, are events at the nuclei of seemingly isolated galaxies, the collision hypothesis was abandoned. Efforts concentrated on the understanding of the activity as internal processes in the host galaxies, possibly aided by infall of gas from the intergalactic medium (cf. Rees, 1978; Gunn, 1979).

scholarly journals Spectral Variations of AG Dra Between 1981 and 1985

1988 ◽  
Vol 103 ◽  
pp. 205-207
Author(s):  
C.C. Huang ◽  
Y.F. Chen ◽  
L. Chen
Keyword(s):  
Emission Line ◽  
Active Phase ◽  
The Other ◽  
Emission Lines ◽  
Continuum Emission ◽  
Late Type ◽  
Stellar Spectrum ◽  
Cool Component ◽  
Strong Emission ◽  
Emission Line Spectrum

After a long quiet phase AG Dra underwent an outstandingly active phase with two outbursts in 1980 Nov. and 1981 Nov.(Viotti et al, 1984). Since then a new quiet phase has followed. In this work we analyse two spectra of AG Dra, of which, one was taken in 1981 by C.C. Huang at the Haute-Provence Observatory using the Marly spectrograph with a dispersion of 80 A/mm at the 1.2 m telescope, the other was obtained by Dr Y.Andrillat in 1985 with the same instrument.Figure 1 shows the spectral variations of AG Dra between 1981 and 1985. The main features of the emission line spectrum are not much different between the two spectra, except that in 1985 there was a new wide weak emission line at 3488 A possibly due to FeII. There were a lot of strong emission lines due to H, HeI, HeII and 0III in both spectra. The spectrum of the late-type component was much more obvious in 1985 than in 1981. In 1985 the lines of CaII K, CaIλ4227 and the G-band of CH were quite strong. In addition we measured a lot of absorption lines due to FeI, SrII and TiII on the 1985 plate. The Balmer continuum emission and the blue contiuum were enhanced in 1981. On the 1981 plate the stellar spectrum in ultraviolet can be traced beyond 3200 A and the blue continuum heavily veiled the spectrum of the cool component. In 1985 they were much weaker.

scholarly journals Chemical Composition of Nova Cygni 1975

1977 ◽  
Vol 42 ◽  
pp. 274-278
Author(s):  
A.A. Boyarchuk
Keyword(s):  
Chemical Composition ◽  
Spectral Type ◽  
Growth Analysis ◽  
Crimean Astrophysical Observatory ◽  
Emission Lines ◽  
Absorption Lines ◽  
Strong Emission ◽  
Light Maximum ◽  
No Emissions

AbstractThe chemical composition of Nova Cygni 1975 was determined by a curve-of-growth analysis. A strong excess of helium and the CNO -group abundances and a normal Si abundance was found.Spectral observations of N Cyg 1975 were begun at the Crimean Astrophysical Observatory on 29 August 1975, at 18h 50m UT, one day before light maximum (Boyarchuk et al. 1977). Twelve spectrograms with a dispersion of 4,6 and 12 Å/mm were taken during this night. The spectral type of the Nova was B2 Ia+ and no emissions appeared in the spectrum. During the following night, 10 spectrograms were obtained. The spectral type of the Nova was A2 Ia+ qe, and strong emission lines with P Cygni-type profiles could be detected. Since absorption lines were not observed on 30 August, only the spectrograms taken on 29 August can be used for a curve-of-growth analysis.

scholarly journals Luminosity Calibration of Late-Type Stars by Statistical Parallax using AGK3 Proper Motions

1978 ◽  
Vol 80 ◽  
pp. 429-432
Author(s):  
Keiichi Ishida ◽  
Takao Mikami
Keyword(s):  
Spectral Type ◽  
Classification System ◽  
The Other ◽  
Spectral Features ◽  
Spectral Classification ◽  
Proper Motions ◽  
Late Type ◽  
Other Hand

The luminosity of individual late-type stars is estimated mainly by spectral features in the MK spectral classification system or by means of the Wilson-Bappu effect. The MK spectral type is given for spectra with a dispersion of about 100 Å mm−1which is within the reach of some Schmidt telescopes with objective prisms. On the other hand, the Wilson-Bappu effect is measured from spectra with a dispersion of about 10 Å mm−1, obtained by coudé spectrographs. In either case the luminosities must be calibrated by knowledge of apparent magnitudes and distances for some stars.

scholarly journals The SAMI Galaxy Survey: reconciling strong emission line metallicity diagnostics using metallicity gradients

2021 ◽  
Vol 502 (3) ◽  
pp. 3357-3373
Author(s):  
Henry Poetrodjojo ◽  
Brent Groves ◽  
Lisa J Kewley ◽  
Sarah M Sweet ◽  
Sebastian F Sanchez ◽  
...  
Keyword(s):  
Emission Line ◽  
Electron Temperature ◽  
Gas Phase ◽  
Mass Range ◽  
Accurate Method ◽  
Emission Lines ◽  
Mass Relation ◽  
Strong Emission ◽  
Data Release ◽  
Accurate Comparison

ABSTRACT We measure the gas-phase metallicity gradients of 248 galaxies selected from Data Release 2 of the SAMI Galaxy Survey. We demonstrate that there are large systematic discrepancies between the metallicity gradients derived using common strong emission line metallicity diagnostics. We determine which pairs of diagnostics have Spearman’s rank coefficients greater than 0.6 and provide linear conversions to allow the accurate comparison of metallicity gradients derived using different strong emission line diagnostics. For galaxies within the mass range 8.5 < log (M/M⊙) < 11.0, we find discrepancies of up to 0.11 dex/Re between seven popular diagnostics in the metallicity gradient–mass relation. We find a suggestion of a break in the metallicity gradient–mass relation, where the slope shifts from negative to positive, occurs between 9.5 < log (M/M⊙) < 10.5 for the seven chosen diagnostics. Applying our conversions to the metallicity gradient–mass relation, we reduce the maximum dispersion from 0.11 dex/Re to 0.02 dex/Re. These conversions provide the most accurate method of converting metallicity gradients when key emission lines are unavailable. We find that diagnostics that share common sets of emission line ratios agree best, and that diagnostics calibrated through the electron temperature provide more consistent results compared to those calibrated through photoionization models.

scholarly journals A Deep Large area Search for Low Luminosity Stars

1998 ◽  
Vol 11 (1) ◽  
pp. 435-435
Author(s):  
Hugh R.A. Jones ◽  
Mike R.S. Hawkins
Keyword(s):  
Spectral Type ◽  
Low Temperatures ◽  
Current Model ◽  
Brown Dwarfs ◽  
Evolutionary Models ◽  
Spectral Indices ◽  
Late Type ◽  
Brown Dwarf ◽  
Large Area ◽  
M Dwarfs

In a recent survey for faint red stars from a digital stack of Schmidt plates a number of candidate objects were identified. Parallax’s for three of these objects have been reported showing them to have luminosities which interpreted within the available evolutionary models indicate them to be good brown dwarf candidates. Here we examine spectra of these objects and others from the plate stack. Using standard spectral indices we find that for a given spectral type their spectra are more consistent with the Pleiades brown dwarfs (PPL 15, Teide 1 and Calar 3) than with standard late-type M dwarfs. Our interpretation is that this is due to their selection by RF IN colours which at values > 3 preferentially selects objects with relatively low gravities. For late-type M dwarfs and brown dwarfs low gravities are expected to be a reliable indication of youth. We also notice that the stack objects generally have strong FeH absorption for their spectral type. Current model atmospheres suggest that FeH strongly increases in strength toward lower metallicities and lower temperatures. We believe that this is not consistent with the available observational evidence from late-type M dwarfs. It is possible that solid Fe is forming inthe low temperature atmospheres relatively depleting FeH strengths toward lower temperatures. We find some evidence that for dwarfs at low temperatures dust formation is less prevalent in lower gravity objects suggesting that dwarfs at low temperatures stronger FeH may be an indication of youth. In addition to the spectral evidence the three stack objects whose parallax’s have been measured show small tangential velocities which is a further indication of youth.

Dissecting quasars with the J-PAS narrow-band photometric survey

2019 ◽  
Vol 15 (S356) ◽  
pp. 12-16
Author(s):  
Silvia Bonoli ◽  
Giorgio Calderone ◽  
Raul Abramo ◽  
Jailson Alcaniz ◽  
Narciso Benitez ◽  
...  
Keyword(s):  
Emission Line ◽  
Wavelength Range ◽  
Software Package ◽  
Narrow Band ◽  
Active Galaxies ◽  
Emission Lines ◽  
Low Resolution ◽  
Strong Emission ◽  
Optical Wavelength ◽  
Quasar Spectra

AbstractThe J-PAS survey will soon start observing thousands of square degrees of the Northern Sky with its unique set of 56 narrow band filters covering the entire optical wavelength range, providing, effectively, a low resolution spectra for every object detected. Active galaxies and quasars, thanks to their strong emission lines, can be easily identified and characterized with J-PAS data. A variety of studies can be performed, from IFU-like analysis of local AGN, to clustering of high-z quasars. We also expect to be able to extract intrinsic physical quasar properties from the J-PAS pseudo-spectra, including continuum slope and emission line luminosities. Here we show the first attempts of using the QSFit software package to derive the properties for 22 quasars at 0.8 < z < 2 observed by the miniJPAS survey, the first deg2 of J-PAS data obtained with an interim camera. Results are compared with the ones obtained by applying the same software to SDSS quasar spectra.

scholarly journals By Draconis and RS Canum Venaticorum Stars: The Discoveries of Classical Photometry and Spectroscopy

1980 ◽  
Vol 5 ◽  
pp. 847-848 ◽  
Author(s):  
Bernard W. Bopp
Keyword(s):  
Spectroscopic Binaries ◽  
Physical Parameters ◽  
Late Type ◽  
Double Line ◽  
Strong Emission ◽  
Rs Cvn Stars ◽  
Ceti Type ◽  
The Common ◽  
Orbital Periods ◽  
Detached Binaries

Physically quite dissimilar, the BY Dra and RS CVn stars have the common characteristic of extraordinarily high levels of stellar surface activity.The RS CVn group, as defined by Hall, consists of detached binaries both components of types F, G, or K. The orbital periods are from a few days to a few weeks, and the mass ratios are generally near unity. Spectroscopically, the stars are remarkable in that they show very strong Ca II H and K emission outside eclipse. Masses and radii are known for many of these systems; physical parameters indicate these systems contain a moderately evolved subgiant, with mass slightly greater than 1 M⊚. The ages (which may be verified by data on visual companions) are a few 10 years.In contrast, the BY Dra variables are late-type dwarfs, with spectral types ranging from dK5e to dM4e. The e designation indicates the presence of Balmer emission, which is generally visible in moderate strength at Ha and only very weakly present in the blue. The BY Dra stars do exhibit strong emission at H and K, however, and also show UV Ceti-type flares. Approximately 75% of the BY Dra variables are known as double-line spectroscopic binaries.

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