The Orbit of the Close Companion of Polaris: Hubble Space Telescope Imaging, 2007 to 2014

  title={The Orbit of the Close Companion of Polaris: Hubble Space Telescope Imaging, 2007 to 2014},
  author={Nancy Remage Evans and Margarita Karovska and Howard E. Bond and Gail H. Schaefer and Kailash C. Sahu and Jennifer Mack and Edmund P. Nelan and Alexandre Gallenne and Evan Tingle},
  journal={The Astrophysical Journal},
As part of a program to determine the dynamical masses of Cepheids, we have imaged the nearest and brightest Cepheid, Polaris, with the Hubble Space Telescope (HST) Wide Field Planetary Camera 2 and Wide Field Camera 3. Observations were obtained at three epochs between 2007 and 2014. In these images, as in HST frames obtained in 2005 and 2006, which we discussed in a 2008 paper, we resolve the close companion Polaris Ab from the Cepheid Polaris Aa. Because of the small separation and large… 

Multiplicity of Galactic Cepheids from long-baseline interferometry

Aims. We aim at detecting and characterizing the main-sequence companions of a sample of known and suspected Galactic binary Cepheids. The long-term objective is to accurately and independently

The Mass of the Cepheid V350 Sgr

V350 Sgr is a classical Cepheid suitable for mass determination. It has a hot companion which is prominent in the ultraviolet (UV) and which is not itself a binary. We have obtained two

HD 344787: a true Polaris analogue?

Context. Classical Cepheids (DCEPs) are the most important primary indicators for the extragalactic distance scale, but they are also important objects in their own right, allowing us to place

Multiplicity of Galactic Cepheids and RR Lyrae stars from Gaia DR2

Context. Classical Cepheids (CCs) and RR Lyrae stars (RRLs) are important classes of variable stars used as standard candles to estimate galactic and extragalactic distances. Their multiplicity is

Probing Polaris’ puzzling radial velocity signals

  • R. Anderson
  • Physics, Geology
    Astronomy & Astrophysics
  • 2019
We investigate temporally changing variability amplitudes and the multi-periodicity of the type-I Cepheid Polaris using 161 high-precision radial velocity (RV) and bisector inverse span (BIS)

Orbital elements of double stars: BU 602 and HU 143 Aa,Ab

HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and

A Geometrical 1% Distance to the Short-period Binary Cepheid V1334 Cygni

Cepheid stars play a considerable role as extragalactic distances indicators, thanks to the simple empirical relation between their pulsation period and their luminosity. They overlap with that of




Polaris, the nearest and brightest classical Cepheid, is a single-lined spectroscopic binary with an orbital period of 30 yr. Using the High Resolution Channel of the Advanced Camera for Surveys on

Hubble Space Telescope Trigonometric Parallax of Polaris B, Companion of the Nearest Cepheid

Polaris, the nearest and brightest Cepheid, is a potential anchor point for the Leavitt period–luminosity relation. However, its distance is a matter of contention, with recent advocacy for a

The long-period Galactic Cepheid RS Puppis - III. A geometric distance from HST polarimetric imaging of its light echoes

As one of the most luminous Cepheids in the Milky Way, the 41.5-day RS Puppis is an analog of the long-period Cepheids used to measure extragalactic distances. An accurate distance to this star would

Extended envelopes around Galactic Cepheids. II. Polaris and delta Cephei from near-infrared interfe

We present the results of long-baseline interferometric observations of the classical Cepheids Polaris and δ  Cep in the near infrared K'  band (1.9-2.3  μ m), using the FLUOR instrument of the CHARA


Deriving the distribution of binary parameters for a particular class of stars over the full range of orbital separations usually requires the combination of results from many different observing

New Parallaxes of Galactic Cepheids from Spatially Scanning the Hubble Space Telescope: Implications for the Hubble Constant

We present new measurements of the parallax of seven long-period (≥10 days) Milky Way (MW) Cepheid variables (SS CMa, XY Car, VY Car, VX Per, WZ Sgr, X Pup, and S Vul) using one-dimensional

Homing in on Polaris: A 7 M⊙ first-overtone Cepheid entering the instability strip for the first time

A recently presented HST/FGS parallax measurement of the Polaris system has been interpreted as evidence for the Cepheid Polaris Aa to be pulsating in the second overtone. An age discrepancy between

Multiplicity of Galactic Cepheids from long-baseline interferometry I. CHARA/MIRC detection of the companion of V1334 Cygni

Context. More than 60% of Cepheids are in binary or multiple systems. Studying such systems could lead to a better understanding of the age and evolution of Cepheids. These are also useful tools to

Polaris the Cepheid Returns: 4.5 Years of Monitoring from Ground and Space

We present the analysis of 4.5 years of nearly continuous observations of the classical Cepheid Polaris, which comprise the most precise data available for this star. We have made spectroscopic


Polaris has a spectroscopic orbit determined from an extensive series of observations as well as a more uncertain astrometric orbit. The determination of its mass and evolutionary state is of