Faint Sources in theEUVESurvey: Identification of White Dwarfs, Active Late‐Type Stars, and Galactic Nuclei

1997 ◽  
Vol 486 (1) ◽  
pp. 179-196 ◽  
Author(s):  
Elisha Polomski ◽  
Stephane Vennes ◽  
John R. Thorstensen ◽  
Mihalis Mathioudakis ◽  
Emilio E. Falco
Keyword(s):  
White Dwarfs ◽  
Galactic Nuclei ◽  
Late Type

scholarly journals SDSS J211852.96−073227.5: The first non-local, interacting, late-type intermediate Seyfert galaxy with relativistic jets

2020 ◽  
Vol 636 ◽  
pp. L12 ◽  
Author(s):  
E. Järvelä ◽  
M. Berton ◽  
S. Ciroi ◽  
E. Congiu ◽  
A. Lähteenmäki ◽  
...  
Keyword(s):  
Near Infrared ◽  
Gamma Ray ◽  
Galactic Nuclei ◽  
Seyfert Galaxy ◽  
Late Type ◽  
Host Galaxies ◽  
Relativistic Jets ◽  
Galaxy Interactions ◽  
Non Local ◽  
First Time

It has been often suggested that a tangible relation exists between relativistic jets in active galactic nuclei (AGN) and the morphology of their host galaxies. In particular, relativistic jets may commonly be related to merging events. Here we present for the first time a detailed spectroscopic and morphological analysis of a Seyfert galaxy, SDSS J211852.96−073227.5, at z = 0.26. This source has previously been classified as a gamma-ray emitting narrow-line Seyfert 1 galaxy. We re-observed it with the 6.5 m Clay Telescope and these new, high-quality spectroscopic data have revealed that it is actually an intermediate-type Seyfert galaxy. Furthermore, the results of modelling the Ks-band near-infrared images obtained with the 6.5 m Baade Telescope indicate that the AGN is hosted by a late-type galaxy in an interacting system, strengthening the suggested connection between galaxy interactions and relativistic jets.

Faint Sources in the EUVE Survey. II. Identification of Two White Dwarfs and Four Late-Type Active Stars.

1997 ◽  
Vol 114 ◽  
pp. 1567 ◽  
Author(s):  
Stephane Vennes ◽  
Eric Korpela ◽  
Stuart Bowyer
Keyword(s):  
White Dwarfs ◽  
Late Type ◽  
Active Stars

scholarly journals Examining supernova events in Type 1 active galactic nuclei

2020 ◽  
Vol 495 (4) ◽  
pp. 4419-4429
Author(s):  
Beatriz Villarroel ◽  
Iñigo Imaz ◽  
Elisabeta Lusso ◽  
Sébastien Comerón ◽  
M Almudena Prieto ◽  
...  
Keyword(s):  
Active Galactic Nuclei ◽  
Detection Rate ◽  
Statistical Study ◽  
Galactic Nuclei ◽  
Core Collapse ◽  
Late Type ◽  
Host Galaxies ◽  
Specific Kind

ABSTRACT A statistical study of intermediate Palomar Transient Factory supernovae (SNe) in Type 1 active galactic nuclei (AGNs) has shown a major deficit of supernovae around Type 1 AGN host galaxies, with respect to Type 2 AGN hosts. The aim of this work is to test whether there is any preference for Type 1 AGNs to host SN of a specific kind. Through the analysis of SN occurrence and their type (thermonuclear versus core-collapse), we can directly link the type of stars producing the SN events, thus this is an indirect way to study host galaxies in Type 1 AGNs. We examine the detection fractions of SNe, the host galaxies and compare the sample properties to typical host galaxies in the Open Supernova Catalog (OSC). The majority of the host galaxies in the AGN sample are late type, similar to typical galaxies hosting SN within the OSC. The findings are supportive of a deficiency of SNe near Type 1 AGNs, although we cannot with certainty assess the overall detection fractions of SNe in Type 1 AGNs relative to other SN host galaxies. We can state that Type 1 AGN has equal detection fractions of thermonuclear versus core-collapse SNe. However, we note the possibility of a higher detection rate of core-collapse supernovae in Type 1 AGN with insecure AGN classifications.

scholarly journals On the Separations of Common Proper Motion Binaries Containing White Dwarfs

1989 ◽  
Vol 114 ◽  
pp. 454-457
Author(s):  
T.D. Oswalt ◽  
E.M. Sion
Keyword(s):  
Mass Loss ◽  
White Dwarf ◽  
Proper Motion ◽  
White Dwarfs ◽  
Main Sequence ◽  
Late Type ◽  
Class A ◽  
Color Class

Luyten [1,2] and Giclas et al. [3,4] list over 500 known common proper motion binaries (CPMBs) which, on the basis of proper motion and estimated colors, are expected to contain at least one white dwarf (WD) component, usually paired with a late type main sequence (MS) star. Preliminary assessments of the CPMBs suggest that nearly all are physical pairs [5,6]. In this paper we address the issue of whether significant orbital expansion has occurred as a consequence of the post-MS mass loss expected to accompany the formation of the WDs in CPMBs.Though the CPMB sample remains largely unobserved, a spectroscopic survey of over three dozen CPMBs by Oswalt [5] found that nearly all faint components of Luyten and Giclas color class “a-f” and “+1”, respectively, or bluer were a WD. This tendency was also evident in a smaller sample studied by Greenstein [7]. Conversely, nearly all CPMBs having two components of color class “g-k” and “+3” or redder were MS+MS pairs. With the caveat that such criteria discriminate against CPMBs containing cool (but rare) WDs, they nonetheless provide a crude means of obtaining statistically significant samples for the comparison of orbital separations: 209 highly probable WD+MS pairs and 109 MS+MS pairs.

scholarly journals The dependence of mass and environment on the secular processes of AGNs in terms of morphology, colour, and specific star-formation rate

2018 ◽  
Vol 620 ◽  
pp. A113 ◽  
Author(s):  
M. Argudo-Fernández ◽  
I. Lacerna ◽  
S. Duarte Puertas
Keyword(s):  
Star Formation ◽  
Active Galactic Nuclei ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Galactic Nuclei ◽  
Stellar Mass ◽  
High Mass ◽  
Late Type ◽  
Star Forming ◽  
Isolated Galaxies

Context. Galaxy mass and environment play a major role in the evolution of galaxies. In the transition from star-forming to quenched galaxies, active galactic nuclei (AGNs) also have a principal action therein. However, the connections between these three actors are still uncertain. Aims. In this work we investigate the effects of stellar mass and the large-scale structure (LSS) environment on the fraction of optical nuclear activity in a population of isolated galaxies, where AGN would not be triggered by recent galaxy interactions or mergers. Methods. As a continuation of a previous work, we focus on isolated galaxies to study the effect of stellar mass and the LSS in terms of morphology (early- and late-type), colour (red and blue), and specific star-formation rate (quenched and star-forming). To explore where AGN activity is affected by the LSS, we separate galaxies into two groups, of low- and high mass, respectively, and use the tidal strength parameter to quantify the effects. Results. We found that AGN is strongly affected by stellar mass in “active” galaxies (namely late-type, blue, and star-forming), but that mass has no influence on “quiescent” galaxies (namely early-type, red, and quenched), at least for masses down to 1010 M⊙. In relation to the LSS, we found an increase in the fraction of star-forming nuclei galaxies with denser LSS in low-mass star-forming and red isolated galaxies. Regarding AGN, we find a clear increase in the fraction of AGNs with denser environment in quenched and red isolated galaxies, independently of the stellar mass. Conclusions. Active galactic nuclei activity appears to be “mass triggered” in active isolated galaxies. This means that AGN activity is independent of the intrinsic properties of the galaxies, but is dependent on their stellar mass. On the other hand, AGN activity appears to be “environment triggered” in quiescent isolated galaxies, where the fraction of AGNs as a function of specific star formation rate and colour increases from void regions to denser LSS, independently of stellar mass.

scholarly journals CCD Parallaxes for Southern Very Low Luminosity Stars

1993 ◽  
Vol 156 ◽  
pp. 75-78
Author(s):  
Philip A. Ianna
Keyword(s):  
White Dwarfs ◽  
Late Type ◽  
M Dwarfs ◽  
Dwarf Stars ◽  
Ccd Observations ◽  
Trigonometric Parallaxes ◽  
M Dwarf Stars ◽  
M Dwarf

Trigonometric parallaxes based on CCD observations are presented here for six southern very late-type M dwarf stars and three white dwarfs. The M dwarfs RG0050-2722, ESO207-61, MH2115-4518, MH2124-4228, and LHS3003 are among the very lowest luminosity stars known.

scholarly journals SpitzerUncovers Active Galactic Nuclei Missed by Optical Surveys in Seven Late‐Type Galaxies

2008 ◽  
Vol 677 (2) ◽  
pp. 926-942 ◽  
Author(s):  
S. Satyapal ◽  
D. Vega ◽  
R. P. Dudik ◽  
N. P. Abel ◽  
T. Heckman
Keyword(s):  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Late Type ◽  
Optical Surveys

Magnetic White Dwarfs in Binary Systems

1982 ◽  
Vol 4 (4) ◽  
pp. 328-334 ◽  
Author(s):  
D.T. Wickramasinghe
Keyword(s):  
Standard Model ◽  
White Dwarfs ◽  
Binary Systems ◽  
Cataclysmic Variables ◽  
Accretion Disc ◽  
Type Star ◽  
Close Binary ◽  
Late Type ◽  
The Standard Model ◽  
Late Type Star

The cataclysmic variables are close binary systems consisting of a late type star and a collapsed star, usually a white dwarf, undergoing mass exchange. According to the standard model, the late type star (the secondary) fills its Roche lobe and material escaping from the inner Lagrangian point is transferred to the primary by means of a mass transfer stream and an accretion disc. The spectroscopic and photometric properties of most cataclysmic variables can be understood in terms of radiation from the various components of such a system, with the accretion disc usually dominating in the optical region (see Warner (1976) for a review). However, recently a new class of cataclysmic variables has been discovered with distinctive optical properties that are inexplicable in terms of the standard model. These systems known as the AM Herculis type variables have provided the first direct evidence for the presence of strong magnetic fields in the white dwarfs of some cataclysmic variables. We present here a review of some of the important properties of these variables with emphasis on the unique system VV Puppis which has provided the first unequivocal evidence for high harmonic cyclotron radiation from white dwarfs.

scholarly journals The Nature of Liners

1987 ◽  
Vol 121 ◽  
pp. 421-441
Author(s):  
Timothy M. Heckman
Keyword(s):  
Emission Line ◽  
Active Galactic Nucleus ◽  
Galactic Nuclei ◽  
High Energy ◽  
Early Type ◽  
Late Type ◽  
Extragalactic Astronomy ◽  
Alternative Models ◽  
Accretion Flows ◽  
Peculiar Galaxies

LINER's (Low-Ionization Nuclear Emission-line Regions) are found in the majority of early-type (Sb or earlier) galaxies, and in some late-type and peculiar galaxies as well. Because they are so common but are not energized by normal stars, their nature is critical to our understanding of both the active galactic nucleus phenomenon and the evolution of normal galactic nuclei. After briefly reviewing the spectroscopic basis of the LINER classification, I summarize four alternative models for LINER's: 1) LINER's as “mini-Seyferts” in which the emission-line gas is photoionized by a more dilute version of the high-energy nonstellar continuum found in Seyfert nuclei. 2) LINER's as accretion flows of cooling gas originating in the halos of galaxies and/or in the intra-cluster medium. 3) LINER's as starburst-driven winds. 4) LINER's as colliding, shock-heated galaxies. After reviewing the evidence, I conclude that it is very likely that several (and possibly all) of the above models are needed to account for the diverse properties of LINER's. While LINER's would then not have a single unified explanation, they would have a direct bearing on many issues in extragalactic astronomy.

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