Publications de Richard Irving Anderson

Mass of Cepheid V350 Sgr Incorporating Interferometry and the Companion Mass

The system V350 Sgr has a classical Cepheid for the primary. Interferometry is presented for the system, and the full orbit is determined. The mass of the companion has been determined from an International Ultraviolet Explorer spectrum and comparison with ...

IOP Publishing Ltd2025

The VELOCE modulation zoo II. Humps and splitting patterns in spectral lines of classical Cepheids

Richard Irving Anderson, Henryka Ewa Netzel

Context. Line splitting in spectral lines is observed in various types of stars due to phenomena such as shocks, spectroscopic binaries, magnetic fields, spots, and nonradial modes. In pulsating stars, line splitting is often attributed to pulsation-induce ...

2025

Variable stars in Galactic globular clusters: II. Population II Cepheids

Richard Irving Anderson

We identified a sample of 88 bona fide Population II Cepheids (henceforth referred to as Cepheids) and 44 candidates in Galactic globular clusters (GCs). Seventy-eight of the Cepheids in the sample align within 2 sigma of the period-luminosity relation for ...

EDP SCIENCES S A2025

The VELOCE modulation zoo III. Detecting additional pulsation modes in optical spectra of classical Cepheids using semi-partial distance correlation periodograms

Richard Irving Anderson

Known for their large amplitude radial pulsations, classical Cepheids are critical standard candles in astrophysics. However, they also exhibit various pulsational irregularities and additional signals that provide deeper insights into their structure and ...

2025

Discovery of a dormant 33 solar-mass black hole in pre-release Gaia astrometry

Richard Irving Anderson

Context. Gravitational waves from black-hole (BH) merging events have revealed a population of extra-galactic BHs residing in short-period binaries with masses that are higher than expected based on most stellar evolution models-And also higher than known ...

2024

Variable stars in galactic globular clusters I. The population of RR Lyrae stars

Richard Irving Anderson, Henryka Ewa Netzel

We present a comprehensive catalog of 2824 RR Lyrae stars (RRLs) residing in 115 Galactic globular clusters (GCs). Our catalog includes 1594 fundamental-mode (RRab), 824 first-overtone (RRc), and 28 double-mode (RRd) RRLs, as well as 378 RRLs of an unknown ...

Edp Sciences S A2024

Calibrating and Standardizing the Tip of the Red Giant Branch in the Small Magellanic Cloud Using Small-amplitude Red Giants

Richard Irving Anderson, Nolan Wayne Koblischke

We investigate the absolute calibration of the tip of the red giant branch (TRGB) in the Small Magellanic Cloud (SMC) using small amplitude red giant stars (SARGs) classified by the Optical Gravitational Lensing Experiment (OGLE). We show that all stars ne ...

2024

Small-amplitude Red Giants Elucidate the Nature of the Tip of the Red Giant Branch as a Standard Candle

Richard Irving Anderson, Nolan Wayne Koblischke

The tip of the red giant branch (TRGB) is an important standard candle for determining luminosity distances. Although several 105 small-amplitude red giant stars (SARGs) have been discovered, variability was previously considered irrelevant for the TRGB as ...

Iop Publishing Ltd2024

JWST Observations Reject Unrecognized Crowding of Cepheid Photometry as an Explanation for the Hubble Tension at 8σ Confidence

Richard Irving Anderson

We present high-definition observations with the James Webb Space Telescope (JWST) of >1000 Cepheids in a geometric anchor of the distance ladder, NGC 4258, and in five hosts of eight Type Ia supernovae, a far greater sample than previous studies with JWST ...

Iop Publishing Ltd2024

WST - Widefield Spectroscopic Telescope: Motivation, science drivers and top-level requirements for a new dedicated facility

Jean-Paul Richard Kneib, Richard Irving Anderson

In this paper, we describe the wide-field spectroscopic survey telescope (WST) project. WST is a 12-metre wide-field spectroscopic survey telescope with simultaneous operation of a large field-of-view (3 sq. degree), high-multiplex (20,000) multi-object sp ...

SPIE2024

The Orbit and Mass of the Cepheid AW Per

Richard Irving Anderson

The Cepheid AW Per is a component in a multiple system with a long-period orbit. The radial velocities of Griffin cover the 38 yr orbit well. An extensive program of interferometry with the Center for High Angular Resolution Astronomy array is reported her ...

2024

Exploring the dynamical evolution of Cepheid multiplicity in star clusters and its implications for B-star multiplicity at birth

Richard Irving Anderson

Context. Classical Cepheid variable stars provide a unique probe of binary evolution in intermediate-mass stars over the course of several tens to hundreds of Myr. In addition, understanding binary evolution with the inclusion of cluster dynamics is desira ...

2024

The VELOCE modulation zoo I. Spectroscopic detection of non-radial modes in the first-overtone Cepheids BG Crucis, QZ Normae, V0391 Normae, and V0411 Lacertae

Richard Irving Anderson, Henryka Ewa Netzel

Context. The photometric observations from the recent decade revolutionized our view on classical pulsators. Low-amplitude signals have been detected photometrically in addition to the dominant high-amplitude radial mode pulsations in many RR Lyrae stars a ...

2024

VELOcities of CEpheids (VELOCE): II. Systematic search for spectroscopic binary cepheids

Richard Irving Anderson, Shreeya Sushil Shetye

Classical Cepheids provide valuable insights into the evolution of stellar multiplicity among intermediate-mass stars. Here, we present a systematic investigation of single-lined spectroscopic binaries (SB1s) based on high-precision velocities measured by ...

2024

JWST Validates HST Distance Measurements: Selection of Supernova Subsample Explains Differences in JWST Estimates of Local H0

Richard Irving Anderson

We cross-check the Hubble Space Telescope (HST) Cepheid/Type Ia supernova (SN Ia) distance ladder, which yields the most precise local H0, against early James Webb Space Telescope (JWST) subsamples (∼1/4 of the HST sample) from SH0ES and CCHP, calibrated o ...

2024

The Orbit and Dynamical Mass of Polaris: Observations with the CHARA Array

Richard Irving Anderson

The 30 yr orbit of the Cepheid Polaris has been followed with observations by the Center for High Angular Resolution Astronomy (CHARA) Array from 2016 through 2021. An additional measurement has been made with speckle interferometry at the Apache Point Obs ...

2024

Relation between the geometric shape and rotation of Galactic globular clusters

Richard Irving Anderson

We homogeneously measured the elliptical shapes of 163 globular clusters (GCs) using the on-sky distribution of their cluster members and the third data release of the ESA mission Gaia (DR3). The astrometry enables the differentiation of stars within clust ...

2024

The Components of Cepheid Systems: The FN Vel System

Richard Irving Anderson

Cepheid masses continue to be important tests of evolutionary tracks for intermediate-mass stars as well as important predictors of their future fate. For systems where the secondary is a B star, Hubble Space Telescope ultraviolet spectra have been obtaine ...

2024

Tip of the Red Giant Branch Distances with JWST. II. I-band Measurements in a Sample of Hosts of 10 Type Ia Supernova Match HST Cepheids

Richard Irving Anderson

The Hubble Tension, a >5σ discrepancy between direct and indirect measurements of the Hubble constant (H 0), has persisted for a decade and motivated intense scrutiny of the paths used to infer H 0. Comparing independently derived distances for a set of ga ...

2024

Tip of the Red Giant Branch Distances with JWST: An Absolute Calibration in NGC 4258 and First Applications to Type Ia Supernova Hosts

Richard Irving Anderson

The tip of the red giant branch (TRGB) allows for the measurement of precise and accurate distances to nearby galaxies based on the brightest ascent of low-mass red giant branch stars before they undergo the helium flash. With the advent of JWST, there is ...

Iop Publishing Ltd2024