Publications by 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