scholarly journals Wolf–Rayet stars in M 81 using GTC/OSIRIS: seven new detections, analysis, and classification of the full sample

2020 ◽  
Vol 493 (3) ◽  
pp. 3879-3892
Author(s):  
V M A Gómez-González ◽  
Y D Mayya ◽  
D Rosa-González ◽  
L H Rodríguez-Merino ◽  
J A Toalá ◽  
...  
Keyword(s):  
Massive Star ◽  
Large Magellanic Cloud ◽  
Evolutionary Models ◽  
Spectral Classification ◽  
Entire Sample ◽  
Full Sample ◽  
Evolutionary Path ◽  
Set Up

ABSTRACT We report the detection of seven new Wolf–Rayet (WR) star locations in M 81 using the Multi-Object Spectrograph of the OSIRIS instrument at Gran Telescopio Canarias. These detections are the result of a follow-up of an earlier study using the same instrumental set-up that resulted in the detection of 14 WR locations. We analyse the entire sample of 21 spectra to classify them to one of the known WR sub-types using template spectra of WR stars in the Large Magellanic Cloud (LMC), with similar metallicity to M 81. Taking into consideration the dispersion in the strengths of the bumps for a given WR sub-type, we found that 19 of the 21 locations correspond to individual stars, including all the seven new detections, of sub-types: WNL, WNE, WCE, and the transitional WN/C. None of the detections correspond to WCL or WO types. The positions of these stars in the red bump versus blue bump luminosity diagram agrees well with an evolutionary path according to the Conti scenario. Based on this, we propose this diagram as a straightforward tool for spectral classification of extragalactic WR sources. The detection of individual WR stars in M 81, which is at a distance of 3.6 Mpc, opens up a new environment for testing the massive star evolutionary models.

Ultraviolet Spectral Classification of O and B Stars in the Large Magellanic Cloud

1999 ◽  
Vol 117 (6) ◽  
pp. 2856-2867 ◽  
Author(s):  
Margaret M. Smith Neubig ◽  
Frederick C. Bruhweiler
Keyword(s):  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Spectral Classification ◽  
B Stars

[ITAL]HST[/ITAL]/FOS Spatially Resolved Spectral Classification of Compact OB Groups in the Large Magellanic Cloud

1999 ◽  
Vol 118 (4) ◽  
pp. 1684-1699 ◽  
Author(s):  
Nolan R. Walborn ◽  
Laurent Drissen ◽  
Joel Wm. Parker ◽  
Abhijit Saha ◽  
John W. MacKenty ◽  
...  
Keyword(s):  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Spectral Classification ◽  
Spatially Resolved

scholarly journals The power of low-resolution spectroscopy: On the spectral classification of planet candidates in the ground-based CoRoT follow-up

2015 ◽  
Vol 336 (2) ◽  
pp. 134-144 ◽  
Author(s):  
M. Ammler-von Eiff ◽  
D. Sebastian ◽  
E. W. Guenther ◽  
B. Stecklum ◽  
J. Cabrera
Keyword(s):  
Spectral Classification ◽  
Low Resolution

X-ray spectral classification of supernova remnants in the Large Magellanic Cloud

1982 ◽  
Vol 255 ◽  
pp. 440 ◽  
Author(s):  
D. H. Clark ◽  
I. R. Tuohy ◽  
M. A. Dopita ◽  
D. S. Mathewson ◽  
K. S. Long ◽  
...  
Keyword(s):  
Supernova Remnants ◽  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Spectral Classification ◽  
X Ray

scholarly journals The NGC 346 massive star census

2020 ◽  
Vol 634 ◽  
pp. A6 ◽  
Author(s):  
P. L. Dufton ◽  
C. J. Evans ◽  
D. J. Lennon ◽  
I. Hunter
Keyword(s):  
Magnetic Field ◽  
Massive Star ◽  
Main Sequence ◽  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Evolutionary Models ◽  
Qualitative Comparison ◽  
Single Star ◽  
Early Type Stars ◽  
The Magnetic Field

Previous analyses of two large spectroscopic surveys of early-type stars in the Large Magellanic Cloud (LMC) have found an excess of nitrogen enriched B-type targets with a ve sin i ≤ 40 km s−1 compared with the predictions of single star evolutionary models that incorporate rotational mixing. By contrast, the number of such targets with 40 <  ve sin i ≤ 80 km s−1 was consistent with such models. We have undertaken a similar analysis for 61 B-type targets which lie towards the young cluster, NGC 346 in the Small Magellanic Cloud (SMC). These again have projected rotational velocities, ve sin i ≤ 80 km s−1, are not classified as supergiants, and are apparently single. Approximately 65% of these SMC targets could have nitrogen enhancements of less than 0.3 dex, which is consistent with them having experienced only small amounts of mixing due to their low rotational velocities. However, as with the previous LMC surveys, an excess of stars with low projected rotational velocities, ve sin i ≤ 40 km s−1, and significant nitrogen enrichments is found. This is estimated to be approximately 5% of the total population of apparently single B-type stars or 40% of all stars with current rotational velocities of less than 40 km s−1; these percentages are similar to those found previously for the two LMC samples. For all three surveys, the presence of undetected binaries and other uncertainties imply that these percentages might be underestimated and that it is indeed possible for all the single stars with current rotational velocities of less than 40 km s−1 to be nitrogen enriched. Two possible explanations incorporate the effects of the magnetic field, via either a stellar merger followed by magnetic braking or the evolution of a single star with a large magnetic field. Both mechanisms would appear to be compatible with the observed frequency of nitrogen-enriched stars in the Magellanic Clouds. Differences in the properties of the nitrogen-enriched stars compared with the remainder of the sample would be consistent with the former mechanism. For the latter, a qualitative comparison with Galactic evolutionary models that incorporate magnetic fields is encouraging in terms of the amount of nitrogen enrichment and its presence in stars near the zero-age main sequence.

scholarly journals A Survey of X-ray–Emitting IRAS Galaxies: A New Class of Objects or Hidden AGNs?

1997 ◽  
Vol 159 ◽  
pp. 421-422
Author(s):  
M. Dennefeld
Keyword(s):  
Spectral Resolution ◽  
Cross Correlation ◽  
Unexpected Result ◽  
Frequency Of Occurrence ◽  
Spectral Classification ◽  
X Ray ◽  
New Class ◽  
Sky Survey

A cross-correlation between the IRAS PSC and the ROSAT All-Sky Survey has provided 242 sources detected in both surveys (Boiler et al. 1992). About half of these have redshifts in the literature and a spectral classification. An unexpected result was the discovery of many galaxies with X-ray luminosities up to a few 1043 ergs s−1, yet without Seyfert characteristics in their optical spectra (e.g., Boiler et al. 1993). To investigate this problem further and evaluate the frequency of occurrence of these peculiar objects, a spectroscopic follow-up has been undertaken to:• Determine velocities and luminosities for all the unclassified objects.• Reevaluate the classification of high X-ray luminosity objects previously not recognized as Seyferts. In particular, spectral resolution or coverage and variability are important parameters to consider if one wants to detect faint signs of Seyfert activity.

Note on the spectral classification of carbon stars in the photographic infrared region

1966 ◽  
Vol 24 ◽  
pp. 21-23
Author(s):  
Y. Fujita
Keyword(s):  
Infrared Region ◽  
Spectral Classification ◽  
Carbon Stars

We have investigated the spectrograms (dispersion: 8Å/mm) in the photographic infrared region fromλ7500 toλ9000 of some carbon stars obtained by the coudé spectrograph of the 74-inch reflector attached to the Okayama Astrophysical Observatory. The names of the stars investigated are listed in Table 1.

Die Wirksamkeit eines Frühinterventionsprogramms für Jugendliche mit Computerspiel- und Internetabhängigkeit: Mittelfristige Effekte der PROTECT+ Studie

2020 ◽  
Vol 48 (1) ◽  
pp. 3-14 ◽  
Author(s):  
Carolin Szász-Janocha ◽  
Eva Vonderlin ◽  
Katajun Lindenberg
Keyword(s):  
Internet Use ◽  
Health Problems ◽  
Reliable Change Index ◽  
Gaming Disorder ◽  
Statistical Classification ◽  
Reliable Change ◽  
Classification Of Diseases ◽  
International Statistical Classification

Zusammenfassung. Fragestellung: Das junge Störungsbild der Computerspiel- und Internetabhängigkeit hat in den vergangenen Jahren in der Forschung zunehmend an Aufmerksamkeit gewonnen. Durch die Aufnahme der „Gaming Disorder“ in die ICD-11 (International Statistical Classification of Diseases and Related Health Problems) wurde die Notwendigkeit von evidenzbasierten und wirksamen Interventionen avanciert. PROTECT+ ist ein kognitiv-verhaltenstherapeutisches Gruppentherapieprogramm für Jugendliche mit Symptomen der Computerspiel- und Internetabhängigkeit. Die vorliegende Studie zielt auf die Evaluation der mittelfristigen Effekte nach 4 Monaten ab. Methodik: N = 54 Patientinnen und Patienten im Alter von 9 bis 19 Jahren (M = 13.48; SD = 1.72) nahmen an der Frühinterventionsstudie zwischen April 2016 und Dezember 2017 in Heidelberg teil. Die Symptomschwere wurde zu Beginn, zum Abschluss der Gruppentherapie sowie nach 4 Monaten anhand von standardisierten Diagnostikinstrumenten erfasst. Ergebnisse: Mehrebenenanalysen zeigten eine signifikante Reduktion der Symptomschwere anhand der Computerspielabhängigkeitsskala (CSAS) nach 4 Monaten. Im Selbstbeurteilungsbogen zeigte sich ein kleiner Effekt (d = 0.35), im Elternurteil ein mittlerer Effekt (d = 0.77). Der Reliable Change Index, der anhand der Compulsive Internet Use Scale (CIUS) berechnet wurde, deutete auf eine starke Heterogenität im individuellen Symptomverlauf hin. Die Patientinnen und Patienten bewerteten das Programm zu beiden Follow-Up-Messzeitpunkten mit einer hohen Zufriedenheit. Schlussfolgerungen: Die vorliegende Arbeit stellt international eine der wenigen Studien dar, die eine Reduktion der Symptome von Computerspiel- und Internetabhängigkeit im Jugendalter über 4 Monate belegen konnte.

scholarly journals New optically identified supernova remnants in the Large Magellanic Cloud

2020 ◽  
Vol 500 (2) ◽  
pp. 2336-2358
Author(s):  
Miranda Yew ◽  
Miroslav D Filipović ◽  
Milorad Stupar ◽  
Sean D Points ◽  
Manami Sasaki ◽  
...  
Keyword(s):  
Supernova Remnants ◽  
Supernova Remnant ◽  
Narrow Band Imaging ◽  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Main Body ◽  
Found Objects ◽  
Type Ia ◽  
Optical Sample

ABSTRACT We present a new optical sample of three Supernova Remnants (SNRs) and 16 Supernova Remnant (SNR) candidates in the Large Magellanic Cloud (LMC). These objects were originally selected using deep H α, [S ii], and [O iii] narrow-band imaging. Most of the newly found objects are located in less dense regions, near or around the edges of the LMC’s main body. Together with previously suggested MCSNR J0541–6659, we confirm the SNR nature for two additional new objects: MCSNR J0522–6740 and MCSNR J0542–7104. Spectroscopic follow-up observations for 12 of the LMC objects confirm high [S ii]/H α emission-line ratios ranging from 0.5 to 1.1. We consider the candidate J0509–6402 to be a special example of the remnant of a possible type Ia Supernova (SN) which is situated some 2° (∼1.75 kpc) north from the main body of the LMC. We also find that the SNR candidates in our sample are significantly larger in size than the currently known LMC SNRs by a factor of ∼2. This could potentially imply that we are discovering a previously unknown but predicted, older class of large LMC SNRs that are only visible optically. Finally, we suggest that most of these LMC SNRs are residing in a very rarefied environment towards the end of their evolutionary span where they become less visible to radio and X-ray telescopes.

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