相关论文: The Orbit and Dynamical Mass of Polaris: Observati…
As part of a program to determine dynamical masses of Cepheids, we have imaged the nearest and brightest Cepheid, Polaris, with the Hubble Space Telescope Wide Field Planetary Camera 2 and Wide Field Camera 3. Observations were obtained at…
Polaris, the nearest and brightest classical Cepheid, is a member of at least a triple system. It has a wide ($18''$) physical companion, the F-type dwarf Polaris B. Polaris itself is a single-lined spectroscopic binary with an orbital…
Polaris is the nearest and brightest classical Cepheid, and pulsates with a period of about 4 days. It has long been known as a single-lined spectroscopic binary with an orbital period of 30 yr. Historical photometric and spectroscopic…
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 measurements from ground and photometric…
Polaris, the nearest and brightest classical Cepheid, is a single-lined spectroscopic binary with an orbital period of 30 years. Using the High Resolution Channel of the Advanced Camera for Surveys onboard the Hubble Space Telescope (HST)…
A review is presented of the past 165 years of observation of the 4-day Cepheid Polaris, including the exciting results of the last 50 years, an interval that has produced three orbital solutions for the spectroscopic binary subsystem,…
Cepheid masses are particularly necessary to help solving the mass discrepancy, while independent distance determinations provide crucial test of the period-luminosity relation and Gaia parallaxes. We used CHARA/MIRC to measure the…
We derive the astrometric orbit of the photo-center of the close pair alpha UMi AP (=alpha UMi Aa) of the Polaris multiple stellar system. The orbit is based on the spectroscopic orbit of the Cepheid alpha UMi A (orbital period of AP: 29.59…
Polaris is a highly unusual Cepheid with observed properties that are difficult to reconcile with stellar evolutionary models. Since the initial detection of Polaris' magnetic field in 2020, we have conducted a magnetic monitoring campaign…
Polaris is one of the most observed stars in the night sky, with recorded observations spanning more than 200 years. From these observations, one can study the real-time evolution of Polaris via the secular rate of change of the pulsation…
The Cepheid AW Per is a component in a multiple system with a long period orbit. The radial velocities of Griffin (2016) cover the 38 year orbit well. An extensive program of interferometry with the CHARA array is reported here, from which…
We report new CHARA/MIRC interferometric observations of the Cepheid archetype $\delta$ Cep, which aimed at detecting the newly discovered spectroscopic companion. We reached a maximum dynamic range $\Delta H $ = 6.4, 5.8, and 5.2 mag,…
Polaris is the nearest Cepheid to us and as such holds a special place in our understanding of Cepheids in general and the Leavitt Law. In the past couple of decades, we have learned many new things about the star as a Cepheid and as the…
New instrumentation is providing new insights into intermediate mass pulsating Cepheids, particularly about their formation and history. Three approaches are discussed, using space (Hubble and Chandra) and ground-based studies (radial…
X-ray observations have been made of a sample of 20 classical Cepheids, including two new observations (Polaris and {\it l} Car) reported here. The occurrence of X-ray flux around the pulsation cycle is discussed. Three Cepheids are…
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 parallax of ~10 mas, in contrast with the…
Polaris the Cepheid has been observed for centuries, presenting surprises and changing our view of Cepheids and stellar astrophysics, in general. Specifically, understanding Polaris helps anchor the Cepheid Leavitt law, but the distance…
We present a first results from a long-term program of a radial velocity study of Cepheid Polaris (F7 Ib) aimed to find amplitude and period of pulsations and nature of secondary periodicities. 264 new precise radial velocity measurements…
We give an update on our long-term program of Galactic Cepheids started in 2012, whose goal is to measure the visual orbits of Cepheid companions. Using the VLTI/PIONIER and CHARA/MIRC instruments, we have now detected several com- panions,…
The mass of a Cepheid is a fundamental parameter for studying the pulsation and evolution of intermediate-mass stars. But determining this variable has been a long-standing problem for decades. Detecting the companions (by spectroscopy or…