scholarly journals The nature of the symbiotic candidate 2MASS J07363415+6538548 in the field of NGC 2403

2020 ◽  
Vol 499 (2) ◽  
pp. 2116-2123
Author(s):  
J Merc ◽  
R Gális ◽  
J Kára ◽  
M Wolf ◽  
M Vrašťák
Keyword(s):  
Effective Temperature ◽  
Milky Way ◽  
Photometric Data ◽  
Cataclysmic Variable ◽  
X Rays ◽  
Symbiotic Star ◽  
Symbiotic Stars ◽  
Rotational Period ◽  
Online Database ◽  
X Ray

ABSTRACT New Online Database of Symbiotic Variables includes several poorly characterized objects and candidate symbiotic stars, not only in the Milky Way but also in other galaxies. The goal of the research presented in this paper was to reveal the nature of 2MASS J07363415+6538548, the object discovered as an X-ray source in the field of NGC 2403, and tentatively classified as a symbiotic candidate or a cataclysmic variable. By analysis of available photometric data from ground-based surveys, together with a high-precision photometry from TESS, remarkable astrometric measurements of the Gaia satellite and observations of other surveys spanning from X-rays to infrared, we have found that the object neither not a symbiotic star nor a cataclysmic variable, but rather an active K-type dwarf. The star is located in the distance of 415 pc, has an effective temperature of 4275 K, luminosity of 0.14 L⊙, mass of 0.7 M⊙, and radius of 0.7 R⊙. It has a rotational period ∼ 3 d and is a strong X-ray source with the X-ray luminosity of ∼ $10^{30}\rm \, erg\, s^{-1}$. Gyrochronology and isochrone fitting confirmed that the star is young.

scholarly journals Interstellar Chemistry: Radiation, Dust and Metals

2008 ◽  
Vol 4 (S255) ◽  
pp. 238-245
Author(s):  
Marco Spaans
Keyword(s):  
Milky Way ◽  
Large Fraction ◽  
Chemical Processes ◽  
Molecular Gas ◽  
X Rays ◽  
Feedback Effects ◽  
Interstellar Chemistry ◽  
X Ray ◽  
Metal Abundances ◽  
Dust Surface

AbstractAn overview is given of the chemical processes that occur in primordial systems under the influence of radiation, metal abundances and dust surface reactions. It is found that radiative feedback effects differ for UV and X-ray photons at any metallicity, with molecules surviving quite well under irradiation by X-rays. Starburst and AGN will therefore enjoy quite different cooling abilities for their dense molecular gas. The presence of a cool molecular phase is strongly dependent on metallicity. Strong irradiation by cosmic rays (>200× the Milky Way value) forces a large fraction of the CO gas into neutral carbon. Dust is important for H2 and HD formation, already at metallicities of 10−4 − 10−3 solar, for electron abundances below 10−3.

scholarly journals Optical spectroscopy and X-ray observations of the D-type symbiotic star EF Aql

2020 ◽  
Vol 495 (1) ◽  
pp. 1461-1467
Author(s):  
K A Stoyanov ◽  
K Iłkiewicz ◽  
G J M Luna ◽  
J Mikołajewska ◽  
K Mukai ◽  
...  
Keyword(s):  
High Resolution ◽  
Optical Spectroscopy ◽  
Chemical Elements ◽  
Mass Loss Rate ◽  
X Rays ◽  
Symbiotic Star ◽  
Optical Telescope ◽  
X Ray ◽  
V Band ◽  
Periodogram Analysis

ABSTRACT We performed high-resolution optical spectroscopy and X-ray observations of the recently identified Mira-type symbiotic star EF Aql. Based on high-resolution optical spectroscopy obtained with the Southern African Large Telescope (SALT), we determine the temperature (∼55 000 K) and the luminosity (∼5.3 L⊙) of the hot component in the system. The heliocentric radial velocities of the emission lines in the spectra reveal possible stratification of the chemical elements. We also estimate the mass-loss rate of the Mira donor star. Our Swift observation did not detect EF Aql in X-rays. The upper limit of the X-ray observations is 10−12 erg cm−2 s−1, which means that EF Aql is consistent with the faintest X-ray systems detected so far. Otherwise we detected it with the UltraViolet and Optical Telescope (UVOT) instrument with an average UVM2 magnitude of 14.05. During the exposure, EF Aql became approximately 0.2 UVM2 magnitudes fainter. The periodogram analysis of the V-band data reveals an improved period of 320.4 ± 0.3 d caused by the pulsations of the Mira-type donor star.

scholarly journals X-Ray and Ultraviolet Observations of AG Draconis during Quiescence and Outburst

1987 ◽  
Vol 93 ◽  
pp. 763-763
Author(s):  
A. Cassatella ◽  
F.A. Córdova ◽  
M. Friedjung ◽  
J. Kenyom ◽  
L. Piro ◽  
...  
Keyword(s):  
Orbital Motion ◽  
Uv Light ◽  
Low Energy ◽  
Emission Lines ◽  
Symbiotic Star ◽  
Symbiotic Stars ◽  
Uv Spectrum ◽  
X Ray ◽  
High Ionization ◽  
Ultraviolet Observations

AbstractWe describe the first X-ray monitoring of a symbiotic star during phases of enhanced activity. AG Dra is a Pop II object with a composite spectrum, characterized by a cool K-type component, prominent high ionization emission lines and a strong UV continuum which is attributed to a hot dwarf companion. Periodic variability of the UV radiation during minimum could be attributed to the orbital motion of the system. In April 1980 HEAO-2 detected an intense, soft X-ray flux from AG Dra, stronger than in other symbiotic stars. After one major outburst of November 1980, which continued until 1983, two more outbursts occurred in February 1985 and January 1986, and coordinated X-ray (EXOSAT) and ultraviolet (IUE) observations were organized to study the behaviour of AG Dra during different activity phases. EXOSAT observations made during decline after the 1985 outburst, revealed a weak X-ray flux in the Thin Lexan filter of the Low Energy dedtector. Observations made during minimum, in June and November 1985, at phases 0.22 and 0.50 of the UV light curve, disclosed the presence of an intense X-ray flux, which was not occulted in November. AG Dra was again observed with EXOSAT in February 1986 when the stellar luminosity was still at maximum. No X-ray flux was detected, in spite of the prominent, high ionization UV spectrum observed with IUE.A detailed discussion of the X-ray and ultraviolet results on AG Dra in the light of possible models is in progress.

scholarly journals X-ray detection of the symbiotic star AG Draconis

1982 ◽  
Vol 70 ◽  
pp. 117-121
Author(s):  
Christopher M. Anderson ◽  
Joseph P. Cassinelli ◽  
Nancy A. Oliversen ◽  
Roy V. Myers ◽  
W.T. Sanders
Keyword(s):  
Proportional Counter ◽  
X Rays ◽  
Symbiotic Star ◽  
X Ray ◽  
Intense Source

AbstractThe symbiotic star AG Draconis was observed by the HEAO-2 Imaging Proportional Counter (IPC) and found to be an unusually intense source of very soft X-rays.

scholarly journals Multiwavelength data for bright active galaxies

2011 ◽  
Vol 7 (S284) ◽  
pp. 237-239
Author(s):  
Areg M. Mickaelian ◽  
Hayk V. Abrahamyan ◽  
Gurgen M. Paronyan ◽  
Gohar S. Harutyunyan
Keyword(s):  
Energy Distribution ◽  
Spectral Energy Distribution ◽  
Active Galaxies ◽  
Photometric Data ◽  
Spectral Energy ◽  
X Rays ◽  
Large Area ◽  
X Ray ◽  
Space Objects ◽  
Cross Correlations

AbstractThe spectral energy distribution (SED) gives a complete picture of the radiation of space objects and may result in correct classifications compared to those based only on optical (or other local) spectra. This is especially crucial for active galaxies, both AGN and Starbursts (SB). For this, multiwavelength (MW) data are needed taken from available surveys and catalogs. We have cross-correlated the Catalogue of quasars and active galaxies with all-sky or large-area MW catalogues, such as X-ray ROSAT (BSC and FSC), UV GALEX (MIS and AIS), optical APM, MAPS, USNO-B1.0, GSC 2.3.2, and SDSS DR8, NIR 2MASS, MIR/FIR WISE, IRAS (PSC and FSC) and AKARI (IRC and FIS), radio GB6, NVSS, FIRST, and WENSS. We have established accurate positions and photometry for a few thousands of objects that appeared in the catalog with poor data, as well as achieved the best astrometric and photometric data for all objects. This allowed correct cross-correlations and establishing correct MW data for these objects. As a result, we obtained 34 photometric points from X-rays to radio and using VO tools built SEDs for some 10,000 bright objects. Some data from other surveys were also used, such as Chandra, XMM, Spitzer, etc. All objects were grouped into several forms of SED and were compared to the known optical classes given in the catalog (QSO, BLL, Sy1, Sy1.2–1.9, Sy2, LINER, SB, and HII). This allowed reveal obscured AGN, as well as find previously misclassified objects. A homogeneous classification for these objects was established. The first part of this project is presented; establishment of accurate positions and photometry and cross-correlations with MW catalogs.

scholarly journals UV spectroscopy confirms SU Lyn to be a symbiotic star

2020 ◽  
Vol 500 (1) ◽  
pp. L12-L16
Author(s):  
Vipin Kumar ◽  
Mudit K Srivastava ◽  
Dipankar P K Banerjee ◽  
Vishal Joshi
Keyword(s):  
Near Infrared ◽  
Uv Spectroscopy ◽  
Symbiotic Star ◽  
Symbiotic Stars ◽  
High Excitation ◽  
Uv Spectrum ◽  
Infrared Observations ◽  
X Ray ◽  
The Galaxy ◽  
Type Giant

ABSTRACT SU Lyn, a star that ostensibly appears to be an unremarkable late M type giant, has recently been proposed to be a symbiotic star largely based on its hard X-ray properties. The star does not display, in low-resolution optical spectra, the high excitation lines typically seen in the spectra of symbiotic stars. In this work, ultraviolet (UV), optical, and near-infrared observations are presented, aimed at exploring and strengthening the proposed symbiotic classification for this star. Our far-UV 1300–1800 Å spectrum of SU Lyn, obtained with the ASTROSAT mission’s UVIT payload, shows emission lines of Si iv, C iv, O iii, and N iii in a spectrum typical of symbiotic stars. The UV spectrum robustly confirms SU Lyn’s symbiotic nature. The detection of high excitation lines in a high-resolution optical spectrum further consolidates its symbiotic nature. As is being recognized, the potential existence of other similar symbiotic systems could significantly impact the census of symbiotic stars in the Galaxy.

Supersoft Sources

1998 ◽  
Vol 11 (2) ◽  
pp. 790-793 ◽  
Author(s):  
P. Kahabka
Keyword(s):  
White Dwarf ◽  
Milky Way ◽  
Accretion Rate ◽  
X Rays ◽  
X Ray ◽  
Galactic Source ◽  
Nuclear Burning ◽  
Cooling Phase ◽  
The Stability ◽  
Stability Line

Supersoft X-ray sources are a new class of luminous X-ray binaries discovered with the X-ray telescopes of the Einstein and ROSAT satellites and extensively studied in the optical with ground based telescopes, in the UV with IUE and HST and in X-rays with ROSAT, Beppo-SAX and ASCA (cf. Kahabka & van den Heuvel 1997, van Teeseling 1997). The luminosities derived for a first sample of supersoft sources studied with moderate resolution X-ray spectroscopy (using Beppo-SAX LECS and ASCA SIS detectors, Parmar et al. 1997, Ebisawa et al. 1997) have been predicted to follow Iben’s stability line (Iben 1982), i.e. the location in the Hertzsprung-Russell diagram which separates the plateau phase from the cooling phase. This is not unreasonable as any system experiencing steady-state accretion, i.e. accretion at a rate equalling about the nuclear burning rate will be found close to the stability line. If the accretion rate exceeds this limit then the white dwarf gets bloated and disappears in X-rays. If the accretion rate falls below this limit the white dwarf envelope cools, the luminosity as well as the temperature ceases and the source enters unstable recurrent nuclear burning. From the population synthesis calculations of Yungelson (1996) follows that there exit for the Milky Way a few sources at any epoch which are more massive than 1.2 MQ. They are expected to be extremely X-ray bright and may be standard candles (cf. Table 1 and Figure 1 for the brightest known supersoft sources per galaxy Milky Way to NGC 55). Their spectral distribution is expected to be similar to that of the extremely hot galactic source RXJ0925.7-4758 (it peaks at 1 keV and the flux is distributed from 0.5 to 2 keV, see Figure 2 for the ASCA spectrum of RX J0925.7-4758 (and CAL 87) as derived by Ebisawa et al. 1997).

scholarly journals What X-rays tell us about dark matter halos

2004 ◽  
Vol 220 ◽  
pp. 455-460
Author(s):  
Y.P. Jing
Keyword(s):  
Dark Matter ◽  
Cold Dark Matter ◽  
Milky Way ◽  
State Of The Art ◽  
Careful Analysis ◽  
Accurate Description ◽  
X Rays ◽  
Dark Matter Halos ◽  
Density Profiles ◽  
X Ray

We present a detailed non-spherical modeling of dark matter halos on the basis of a careful analysis of state-of-the art N-body simulations. the fitting formulae presented here form a complete and accurate description of the triaxial density profiles of halos in Cold Dark Matter (CDM) models. This modeling allows us to quantitatively discuss implications for shape observations of galactic and cluster halos. the predictions of the concordance ACDM model are confronted with the shape observations from the Milky Way to X-ray clusters.

scholarly journals XMM-Newton observations of the symbiotic recurrent nova T CrB: evolution of X-ray emission during the active phase

2019 ◽  
Vol 489 (2) ◽  
pp. 2930-2940 ◽  
Author(s):  
Svetozar A Zhekov ◽  
Toma V Tomov
Keyword(s):  
Active Phase ◽  
Soft Component ◽  
X Rays ◽  
Rotational Period ◽  
Hard Component ◽  
X Ray ◽  
Quiescent Phase ◽  
Recurrent Nova ◽  
First Time ◽  
Thin Plasma

ABSTRACT We present an analysis of the XMM-Newton observations of the symbiotic recurrent nova T CrB, obtained during its active phase which started in 2014–2015. The XMM-Newton spectra of T CrB have two prominent components: a soft one (0.2–0.6 keV), well represented by blackbody emission, and a heavily absorbed hard component (2–10 keV), well matched by optically-thin plasma emission with high temperature (kT ≈ 8 keV). The XMM-Newton observations reveal evolution of the X-ray emission from T CrB in its active phase. Namely, the soft component in its spectrum is decreasing with time, while the opposite is true for the hard component. Comparison with data obtained in the quiescent phase shows that the soft component is typical only for the active phase, while the hard component is present in both phases but it is considerably stronger in the quiescent phase. Presence of stochastic variability (flickering) on time-scales of minutes and hours is confirmed both in X-rays and UV (UVM2 filter of the XMM-Newton optical monitor). On the other hand, periodic variability of 6000–6500 s is found for the first time in the soft X-ray emission (0.2–0.6 keV) from T CrB. We associate this periodic variability with the rotational period of the white dwarf in this symbiotic binary.

scholarly journals A systematic search for rapid photometric variability in southern symbiotic stars I. V648 Car

2012 ◽  
Vol 8 (S290) ◽  
pp. 179-180
Author(s):  
Rodolfo Angeloni ◽  
Francesco Di Mille ◽  
Carlos Eduardo Ferreira Lopes ◽  
Nicola Masetti
Keyword(s):  
Time Scales ◽  
Systematic Search ◽  
Symbiotic Star ◽  
Symbiotic Stars ◽  
Small Class ◽  
Photometric Variability ◽  
X Ray ◽  
First Results ◽  
Over Time

AbstractWe present the first results from the systematic observational campaign aimed at studying rapid photometric variability (i.e., flickering) in southern symbiotic stars. In particular, we report on the discovery of strong flickering from V648Car (also known as SS73-17), a poorly studied system belonging to the small class of hard X-ray emitting symbiotic stars. To our knowledge, with a U-band flickering amplitude >0.6mag over time scales of minutes, it is one of the most significant flickering ever reported from a symbiotic star.

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