[论文解读] The Historical Lightcurve of the R Coronae Borealis Star, V854 Cen, from 1890 to 2026

Geoffrey C Clayton|arXiv (Cornell University)|Mar 14, 2026

Stellar, planetary, and galactic studies被引用 0

一句话总结

该论文使用 Harvard DASCH 平板及其他档案数据重建 V854 Cen 的历史光变曲线，揭示在 1980 年前存在一段较暗的长时间期，然后上升至最大光度并随后进入典型的 RCB 活动。

ABSTRACT

The R Coronae Borealis (RCB) Star, V854 Cen, was not discovered until the 1980's even though it is 7th magnitude at maximum light. This is because it was in a faint state due to the presence of thick circumstellar dust clouds for nearly a century. RCB stars are known for having deep declines of up to 9 magnitudes at irregular intervals. The declines are caused by dust clouds which block the light from the star. The historical lightcurve of V854 Cen before discovery was investigated by examining plates taken by Harvard College Observatory and other observatories beginning in 1889. These observations show that V854 Cen was well below 7th magnitude from 1890 to 1980, often as faint as 16th or 17th magnitude.

研究动机与目标

• Investigate the historical brightness variations of V854 Cen prior to its 1980 discovery.
• Combine DASCH and archival plate data to construct a long-term lightcurve.
• Assess challenges in photometry due to close companions and plate limitations.
• Clarify the pre-discovery luminosity behavior of this RCB star.

提出的方法

• Use DASCH photometry of 2634 HCO plates to extract lightcurve data.
• Visually inspect plates to correct for issues when V854 Cen and a nearby companion are merged or saturated.
• Create a photometric sequence for the field using APASS B magnitudes for calibration.
• Incorporate photometry from ASAS-3, ASAS-SN, APPLAUSE, MJUO, SAAO, AAVSO, and other sources to extend the lightcurve.
• Address plate-related issues (seeing, WCS errors, saturation) with photometric techniques such as Photutils FWHM analysis and eye estimates.

Figure 1: The lightcurve of V854 Cen from 1890 to 2026. For the sources of the photometry, see the text.

实验结果

研究问题

• RQ1 What was the brightness behavior of V854 Cen before its discovery in 1986?
• RQ2 How does the pre-discovery lightcurve compare with modern RCB activity after 1980?
• RQ3 What photometric challenges affect historical measurements and how can they be mitigated?
• RQ4 What is the timescale and amplitude of the star’s pre-1980 faint state and subsequent rise to maximum?
• RQ5 How reliable is the DASCH photometry for bright vs. faint states of V854 Cen?

主要发现

• DASCH photometry suggests V854 Cen was well below maximum light until about 1980.
• Prior to 1980, the star was typically 14th magnitude or fainter from 1890 to 1915, with brief brightening around 1917 and a long faint period 1930–1950.
• Between 1954 and 1970 (Menzel gap), observations fill in some periods with slow brightening toward maximum.
• Around 1980 the star returned to maximum brightness, ~7th magnitude, and since then has shown typical RCB variability with declines and recoveries.
• The historical lightcurve constructed is markedly different from the DASCH-only lightcurve, highlighting observational challenges such as blending with a nearby companion and plate saturation.