The Araucaria Project: The Distance to the Sculptor Galaxy NGC 247 From Near-Infrared Photometry of Cepheid Variables

Gieren, W.; Pietrzyński, G.; Soszyński, I.; Szewczyk, O.; Bresolin, Fabio; Kudritzki, Rolf‐Peter; Urbaneja, M. A.; Storm, J.; Minniti, D.; García-Varela, A.

doi:10.1088/0004-637x/700/2/1141

Cited by 38 publications

(33 citation statements)

References 39 publications

(67 reference statements)

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“…We thereby discard the two IR points and choose the UV and optical data from 1350Å to 8000Å in our SED fitting. A distance of 3.4 Mpc to NGC 247 is adopted (Gieren et al 2009).…”

Section: Modelmentioning

confidence: 99%

A Wind-disk Self-irradiation Model for Supercritical Accretion

Yao

Feng

2019

ApJL

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Optical emission from actively accreting X-ray binaries is dominated by X-ray reprocessing on the outer disk. In the regime of supercritical accretion, strong radiation will power a massive wind that is optically thick and nearly spherical, and will occult the central hard X-rays from irradiating the outer disk. Instead, thermal emission from the wind will act as a new source of irradiation. Here, we construct a self-irradiation model, in which the inner disk (within the wind photosphere) is completely blocked by the wind, the middle part (between the wind photosphere and scattersphere) is heated by the wind directly, and the outer disk (beyond the wind scattersphere) is heated by photons leaving the scattersphere. The model can adequately fit the UV/optical SED of NGC 247 X-1, a candidate source with supercritical accretion, while the standard irradiation model fails to produce a self-consistent result. The best-fit parameters suggest that the source contains a stellar mass black hole with an accretion rate roughly 100 times the critical value. Remarkably, the UV/optical fitting predicts a wind photosphere that is well consistent with X-ray measurements, although it is an extrapolation over 3 orders of magnitude in wavelength. This implies that supercritical accretion does power a massive wind and the UV/optical data are useful in constraining the wind structure.

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“…We thereby discard the two IR points and choose the UV and optical data from 1350Å to 8000Å in our SED fitting. A distance of 3.4 Mpc to NGC 247 is adopted (Gieren et al 2009).…”

Section: Modelmentioning

confidence: 99%

A Wind-disk Self-irradiation Model for Supercritical Accretion

Yao

Feng

2019

ApJL

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“…Here, we attempt to unveil the physical origin of the optical emission using multi-band HST observations and the nature of the X-ray emission using multi-epoch observations with XMM-Newton, Chandra, and Swift. We adopt a distance of 3.4Mpc estimated using IR Cepheids to the galaxy NGC 247 (Gieren et al 2009). …”

Section: Introductionmentioning

confidence: 99%

Nature of the Soft Ulx in NGC 247: Super-Eddington Outflow and Transition Between the Supersoft and Soft Ultraluminous Regimes

Feng

Tao

Kaaret

et al. 2016

ApJ

100

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We report on XMM-Newton/Chandra/Swift/Hubble Space Telescope observations of the ultraluminous X-ray source (ULX) in NGC 247, which is found to make transitions between the supersoft ultraluminous (SSUL) regime with a spectrum dominated by a cool (∼0.1 keV) blackbody component and the soft ultraluminous (SUL) regime with comparable luminosities shared by the blackbody and power-law components. Multi-epoch observations revealed an anti-correlation between the blackbody radius and temperature, µ - R T bb bb 2.8 0.3 , ruling out a standard accretion disk as the origin of the soft X-ray emission. The soft X-ray emission is much more variable on both short and long timescales in the SSUL regime than in the SUL regime. We suggest that the SSUL regime may be an extension of the ultraluminous state toward the high accretion end, being an extreme case of the SUL regime, with the blackbody emission arising from the photosphere of thick outflows and the hard X-rays being emission leaked from the embedded accretion disk via the central low-density funnel or advected through the wind. However, the scenario that the supersoft ULXs are standard ULXs viewed nearly edge-on cannot be ruled out. Flux dips on a timescale of 200 s were observed. The dips cannot be explained by an increase of absorption, but could be due to the change of accretion rate or related to thermal fluctuations in the wind or disk. The optical emission of NGC 247 ULX exhibits a blackbody spectrum at a temperature of 19,000K with a radius of 20  R , likely arising from an OB supergiant companion star.

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“…While the objects we use for the distance determinations are usually detected from optical wide-field imaging surveys of the target galaxies (e.g., , the most accurate distance work is then done from follow-up near-infrared images which virtually eliminate reddening as a significant source of error on the results. Examples of this very successful approach are the Cepheid work on the Sculptor galaxies NGC 300 (Gieren et al 2005a), NGC 55 ) and NGC 247 (Gieren et al 2009), and the red clump star work on the Large Magellanic Cloud (LMC; . The Araucaria Project has also been developing a new spectroscopic distance indicator, viz., the flux-weighted gravity-luminosity relationship (FGLR) for blue supergiants (Kudritzki et al 2003 which is able to yield distances accurate to 5% to galaxies containing massive blue stars out to about 10 Mpc from lowresolution spectra Urbaneja et al 2008).…”

Section: Introductionmentioning

confidence: 99%

The Araucaria Project: The Distance to the Small Magellanic Cloud From Near-Infrared Photometry of Rr Lyrae Variables

Szewczyk

Pietrzyński

Gieren

et al. 2009

The Astronomical Journal

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We have obtained deep infrared J-and K-band observations of nine 4.9 × 4.9 arcmin fields in the Small Magellanic Cloud (SMC) with the ESO New Technology Telescope equipped with the SOFI infrared camera. In these fields, 34 RR Lyrae stars cataloged by the OGLE collaboration were identified. Using different theoretical and empirical calibrations of the infrared period-luminosity-metallicity relation, we find consistent SMC distance moduli, and find a best true distance modulus to the SMC of 18.97 ± 0.03 (statistical) ±0.12 (systematic) mag, which agrees well with most independent distance determinations to this galaxy, and puts the SMC 0.39 mag more distant than the Large Magellanic Cloud for which our group has recently derived, from the same technique, a distance of 18.58 mag.

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The Araucaria Project: The Distance to the Sculptor Galaxy NGC 247 From Near-Infrared Photometry of Cepheid Variables

Cited by 38 publications

References 39 publications

A Wind-disk Self-irradiation Model for Supercritical Accretion

A Wind-disk Self-irradiation Model for Supercritical Accretion

Nature of the Soft Ulx in NGC 247: Super-Eddington Outflow and Transition Between the Supersoft and Soft Ultraluminous Regimes

The Araucaria Project: The Distance to the Small Magellanic Cloud From Near-Infrared Photometry of Rr Lyrae Variables

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