The Effect of Metallicity on Cepheid‐based Distances

Sakai, Shoko; Ferrarese, Laura; Kennicutt, R. C.; Saha, Abhijit

doi:10.1086/386540

Cited by 214 publications

(360 citation statements)

References 86 publications

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“…It is close to the large spiral galaxy M83 in projection. However the distance to M83, 4.8 Mpc 39 , is significantly larger than the distance to NGC 5253, at 3.8 Mpc 40 . The HI streamer system 24,25 in the halo of NGC 5253 from which the CO streamer appears to emanate strongly suggests that this dwarf galaxy has had some encounter in its past, but M83 does not appear to be responsible.…”

Section: Methodsmentioning

confidence: 72%

Highly efficient star formation in NGC 5253 possibly from stream-fed accretion

Turner

Beck

Benford

et al. 2015

Nature

103

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Gas clouds in present-day galaxies are inefficient at forming stars. Low star formation efficiency is a critical parameter in galaxy evolution: it is why stars are still forming nearly fourteen billion years after the Big Bang 1 and why star clusters generally do not survive their births, instead dispersing to form galactic disks, halos, or bulges 2 . Yet the existence of ancient massive star clusters in the Milky Way, globular clusters, suggests that efficiencies were higher when they formed ten billion years ago. A local dwarf galaxy, NGC 5253, has a young star cluster that may provide an example of highly efficient star formation 3 . Here we report the detection of the J= 3-2 rotational transition of CO at the location of the massive cluster. The gas cloud is hot, dense, quiescent, and extremely dusty. Its gas-to-dust ratio is lower than the Galactic value, which we attribute to dust enrichment by the embedded star cluster. Its star formation efficiency exceeds 50%, ten times higher than clouds in the Milky Way: this cloud is a factory of stars and soot. We suggest that high efficiency results from the force-feeding of star formation by a streamer of gas falling into the galaxy.The Submillimeter Array image of NGC 5253, shown in Figure 1, reveals a bright CO(3-2) source coincident with the giant cluster and its "supernebula" 4 . "Cloud D" 3 is one of only two molecular clouds detected within the galaxy; the second cloud is smaller and located ~5" (90 pc) to the southwest. A "streamer" of gas extending along the minor axis is also detected in CO(3-2). This streamer, previously detected in lower J CO lines, appears to be falling into the galaxy near the supernebula 3,5 . Both the streamer and Cloud D emit 870µm continuum emission, as shown in Figure 2. Also shown is an image of 350µm continuum, in which both Cloud D and the streamer are detected. Figure 1. CO J=3-2 emission in NGC 5253. The SMA CO(3-2) integrated line intensity, in red, is shown atop a λ814nm Hubble Space Telescope image. The SMA beam is 4" x 2" (74 pc x 37 pc). The field covers 40" x 40" (740 pc x740 pc), north up, east left. Image registration is to < 1". The CO streamer coincides with the optical dust lane to the east. The massive star cluster is located at the bright CO peak, Cloud D; it is embedded 8.9 , and not visible here. Cloud F is to the southwest of Cloud D.The molecular gas in Cloud D is hot. This is clear from the increase in brightness from CO(2-1) 3 to CO(3-2). The intensity ratio of the two lines is I 32 /I 21 = 2.6±0.5 (I line = ∫T line dv). This ratio is nonthermal, although the thermal limit of 2.25 (~ν 2 ) is within the uncertainties, and is what we adopt. Non-LTE modeling of this ratio using RADEX 6 indicates a minimum kinetic temperature of T K > 200 K for the 1σ lower limit, and T K > 350 K for the adopted value of I 32 /I 21 = 2.25 (see Methods). The high gas temperature is consistent with a thermal origin for H 2 2.2µm emission in the region 7 . Cloud D appears to be a Photon-Dominated Region (PDR), heated by ultraviol...

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Section: Methodsmentioning

confidence: 72%

Highly efficient star formation in NGC 5253 possibly from stream-fed accretion

Turner

Beck

Benford

et al. 2015

Nature

103

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“…The calibration of the TRGB magnitude M * I is very solid. Sakai et al (2004) found M * I = −4.05 mag from globular clusters. Rizzi et al (2007) fitted the horizontal branch (HB) of five galaxies to a metal-corrected HB from Hipparcos parallaxes and obtained the same value.…”

Section: The Tip Of the Red-giant Branch (Trgb) As A Distance Indicatormentioning

confidence: 98%

Allan Sandage and the distance scale

Tammann

Reindl

2012

Proc. IAU

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Abstract. Allan Sandage returned to the distance scale and the calibration of the Hubble constant again and again during his active life, experimenting with different distance indicators. In 1952 his proof of the high luminosity of Cepheids confirmed Baade's revision of the distance scale (H0 ∼ 250 km s −1 Mpc −1 ). During the next 25 years, he lowered the value to 75 and 55. Upon the arrival of the Hubble Space Telescope, he observed Cepheids to calibrate the mean luminosity of nearby Type Ia supernovae (SNe Ia) which, used as standard candles, led to the cosmic value of H0 = 62.3 ± 1.3 ± 5.0 km s −1 Mpc −1 . Eventually he turned to the tip of the red-giant branch (TRGB) as a very powerful distance indicator. A compilation of 176 TRGB distances yielded a mean, very local value of H0 = 62.9 ± 1.6 km s −1 Mpc −1 and shed light on the streaming velocities in the Local Supercluster. Moreover, TRGB distances are now available for six SNe Ia; if their mean luminosity is applied to distant SNe Ia, one obtains H0 = 64.6 ± 1.6 ± 2.0 km s −1 Mpc −1 . The weighted mean of the two independent large-scale calibrations yields H0 = 64.1 km s −1 Mpc −1 within 3.6%.

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“…The CMD of the entire WFPC2 field, reaching deeper into the disc population, is swamped with an admixture of evolved AGB stars and supergiants such that the TRGB becomes invisible to the eye and also the edge detection spectrum becomes much noisier (Fig.1 right). Rizzi et al (2007) have remeasured the field of Sakai et al (2004) and found m * I = 25.29 ± 0.08. The mean of m * I = 25.35 ± 0.05 is adopted here.…”

Section: The Trgb In Mixed Populationsmentioning

confidence: 99%

“…With m corr V = 8.92 ± 0.16 and a TRGB distance of (m − M) = 28.21 (Sakai et al 2004;Rizzi et al 2007 …”

Section: The Sn 1937c In Ic 4182mentioning

confidence: 99%

The luminosity of supernovae of type Ia from tip of the red-giant branch distances and the value ofH₀

Tammann¹,

Reindl²

2013

A&A

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Distances from the tip of the red-giant branch (TRGB) in the halo population of galaxies -calibrated through RR Lyr stars as well as tied to Hipparcos parallaxes and further supported by stellar models -are used to determine the luminosity of six nearby type Ia supernovae (SN 2011fe, 2007sr, 1998bu, 1989B, 1972E, and 1937C). The result is M corr V = −19.41 ± 0.05. If this value is applied to 62 SNe Ia with 3000 < v < 20, 000 km s −1 a large-scale value of the Hubble constant follows of H 0 = 64.0 ± 1.6 ± 2.0. The SN HST Project gave H 0 = 62.3 ± 1.3 ± 5.0 from ten Cepheid-calibrated SNe Ia. The near agreement of young Population I (Cepheids) and old, metal-poor Population II (TRGB) distance indicators is satisfactory. The combined weighted result is H 0 = 63.7 ± 2.3 (i.e. ±3.6%). The value will be helpful to constrain models of the early Universe.

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The Effect of Metallicity on Cepheid‐based Distances

Cited by 214 publications

References 86 publications

Highly efficient star formation in NGC 5253 possibly from stream-fed accretion

Highly efficient star formation in NGC 5253 possibly from stream-fed accretion

Allan Sandage and the distance scale

The luminosity of supernovae of type Ia from tip of the red-giant branch distances and the value ofH₀

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The Effect of Metallicity on Cepheid‐based Distances

Cited by 214 publications

References 86 publications

Highly efficient star formation in NGC 5253 possibly from stream-fed accretion

Highly efficient star formation in NGC 5253 possibly from stream-fed accretion

Allan Sandage and the distance scale

The luminosity of supernovae of type Ia from tip of the red-giant branch distances and the value ofH0

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Product

Resources

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The luminosity of supernovae of type Ia from tip of the red-giant branch distances and the value ofH₀