Analysis of HST/COS spectra of the bare C–O stellar core H1504+65 and a high-velocity twin in the Galactic halo

Werner, K.; Rauch, T.

doi:10.1051/0004-6361/201527261

Cited by 43 publications

(50 citation statements)

References 39 publications

(63 reference statements)

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“…1) at a distance of d ≤ 13.3 kpc (Werner & Rauch 2015), thus proving that the gas resides within the inner halo of the Milky Way and is not related to a supposed LMC outflow. The paper is organized as follows.…”

Section: Introductionmentioning

confidence: 79%

“…Since its discovery in 1994 as ROSAT supersoft X-ray source, RX J0439.8−6809 was regarded as a WD located in the LMC (Greiner et al 1994). A recent spectral analysis of RX J0439.8−6809 by Werner & Rauch (2015) based on COS data reveals, however, that the star has a spectroscopic distance of just d = 9.2 +4.1 −7.2 , thus located within the Milky Way halo ∼5.6 kpc below the Galactic disk. The distance and the position (at l = 279.9, b = −37.1) in front of the LMC make RX J0439.8−6809 the ideal target to constrain the distance of intermediate-and high-velocity gas in the direction of the Magellanic Clouds.…”

Section: Observations and Data Handlingmentioning

confidence: 99%

“…We use the same COS data set as presented in Werner & Rauch (2015). RX J0439.8−6809 was observed with HST/COS using the G130M grating that covers the wavelength range between λ = 1150−1450 Å at a spectral resolution of R ≈ 15 000−20 000 (FWHM 15−20 km s −1 ).…”

Section: Observations and Data Handlingmentioning

confidence: 99%

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High-velocity gas toward the LMC resides in the Milky Way halo

Richter

Boer

Werner

et al. 2015

A&A

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Aims. To explore the origin of high-velocity gas in the direction of the Large Magellanic Cloud, (LMC) we analyze absorption lines in the ultraviolet spectrum of a Galactic halo star that is located in front of the LMC at d = 9.2Methods. We study the velocity-component structure of low and intermediate metal ions (C ii, Si ii, Si iii) in the spectrum of RX J0439.8−6809, as obtained with the Cosmic Origins Spectrograph (COS) onboard the Hubble Space Telescope (HST), and measure equivalent widths and column densities for these ions. We supplement our COS data with a Far-Ultraviolet Spectroscopic Explorer (FUSE) spectrum of the nearby LMC star Sk −69 59 and with H i 21 cm data from the Leiden-Argentina-Bonn (LAB) survey.Results. Metal absorption toward RX J0439.8−6809 is unambiguously detected in three different velocity components near v LSR = 0, +60, and +150 km s −1 . The presence of absorption proves that all three gas components are situated in front of the star, thus located in the disk and inner halo of the Milky Way. For the high-velocity cloud (HVC) at v LSR = +150 km s −1 , we derive an oxygen abundance of [O/H] = −0.63 (∼0.2 solar) from the neighboring Sk −69 59 sight line, in accordance with previous abundance measurements for this HVC. From the observed kinematics we infer that the HVC hardly participates in the Galactic rotation. Conclusions. Our study shows that the HVC toward the LMC represents a Milky Way halo cloud that traces low column density gas with relatively low metallicity. We rule out scenarios in which the HVC represents material close to the LMC that stems from a LMC outflow.

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Section: Introductionmentioning

confidence: 79%

Section: Observations and Data Handlingmentioning

confidence: 99%

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High-velocity gas toward the LMC resides in the Milky Way halo

Richter

Boer

Werner

et al. 2015

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“…The effect of thermal pressure [11] of electron and light nucleus species is important not only in hot white dwarfs like RX J0439.8-6809, [29] but also in the partially degenerate plasma [30] regime of white dwarfs. The effect of thermal pressure [11] of electron and light nucleus species is important not only in hot white dwarfs like RX J0439.8-6809, [29] but also in the partially degenerate plasma [30] regime of white dwarfs.…”

Section: Discussionmentioning

confidence: 99%

Self‐gravito‐acoustic waves and their instabilities in a self‐gravitating degenerate quantum plasma system

Mamun

2019

Contributions to Plasma Physics

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A self-gravitating degenerate quantum plasma (SGDQP) system containing degenerate electron and light nucleus species along with extremely low-dense heavy-nucleus species is considered. The existence of new degenerate pressure-driven self-gravito-acoustic (DPDSGA) waves in this SGDQP system is found, and their dispersion properties along with stable and unstable parametric regimes are identified. The DPDSGA waves emit from this SGDQP system due to the compression and rarefaction (and vice-versa) of the perturbed state of it. Its compression is due to the inward poll of degenerate electron and light nucleus species by the self-gravitational attractive pressures, whereas its rarefaction is due to the outward degenerate pressures exerted by the degenerate electron and light nucleus species. The DPDSGA waves are new because they completely disappear if the electron and light nucleus degeneracies are neglected. The DPDSGA waves exist in the SGDQP system that occurs in astrophysical compact objects like white dwarfs [H. M. Van Horn, Science 252, 384 (1991); D. Koester, Astron. Astrophys. Rev. 11, 33 (2002)]. K E Y W O R D Sdegenerate quantum plasmas, self-gravitational instabilities, self-gravito-acoustic waves

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“…15.74 18.58 in these sources are akin to those seen in massive PG1159 stars, such as H1054+65 (e.g. Werner et al 2004) and RX J0439.8−6809 (Werner & Rauch 2015). Both of these massive WDs are extremely hot (T eff > 200 000 K) and consist of atmospheres rich in carbon and oxygen.…”

Section: Propertymentioning

confidence: 90%

The OmegaWhite Survey for short-period variable stars – IV. Discovery of the warm DQ white dwarf OW J175358.85−310728.9

Macfarlane

Woudt

Dufour

et al. 2017

Monthly Notices of the Royal Astronomical Society

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We present the discovery and follow-up observations of the second known variable warm DQ white dwarf OW J175358.85−310728.9 (OW J1753−3107). OW J1753−3107 is the brightest of any of the currently known warm or hot DQ and was discovered in the OmegaWhite Survey as exhibiting optical variations on a period of 35.5452 (2) min, with no evidence for other periods in its light curves. This period has remained constant over the last 2 yr and a singleperiod sinusoidal model provides a good fit for all follow-up light curves. The spectrum consists of a very blue continuum with strong absorption lines of neutral and ionized carbon, a broad He I λ4471 line and possibly weaker hydrogen lines. The C I lines are Zeeman split, and indicate the presence of a strong magnetic field. Using spectral Paschen-Back model descriptions, we determine that OW J1753−3107 exhibits the following physical parameters: T eff = 15 430 K, log (g) = 9.0, log (N(C)/N(He)) = −1.2 and the mean magnetic field strength is B z =2.1 MG. This relatively low temperature and carbon abundance (compared to the expected properties of hot DQs) is similar to that seen in the other warm DQ SDSS J1036+6522. Although OW J1753−3107 appears to be a twin of SDSS J1036+6522, it exhibits a modulation on a period slightly longer than the dominant period in SDSS J1036+6522 and has a higher carbon abundance. The source of variations is uncertain, but they are believed to originate from the rotation of the magnetic white dwarf.

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Analysis of HST/COS spectra of the bare C–O stellar core H1504+65 and a high-velocity twin in the Galactic halo

Cited by 43 publications

References 39 publications

High-velocity gas toward the LMC resides in the Milky Way halo

High-velocity gas toward the LMC resides in the Milky Way halo

Self‐gravito‐acoustic waves and their instabilities in a self‐gravitating degenerate quantum plasma system

The OmegaWhite Survey for short-period variable stars – IV. Discovery of the warm DQ white dwarf OW J175358.85−310728.9

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