Be STARS IN THE OPEN CLUSTER NGC 6830

Yu, Po Chieh; Lin, Chung‐Yen; Lin, Hsing Wen; Lee, Chien De; Konidaris, Nick; Ngeow, Chow-Choong; Ip, W.-H.; Chen, Wen-Ping; Chen, Hui-Chen; Malkan, Matthew A.; Laher, Russ R.; Huang, Li; Cheng, Yu; Ritter, Andreas; Quimby, R.; Ben-Ami, Sagi; Ofek, E. O.; Surace, J.; Kulkarni, S. R.

doi:10.3847/0004-6256/151/5/121

Cited by 4 publications

(2 citation statements)

References 37 publications

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“…The PTF/iPTF project employed various camera filters (some have yet to be documented), including broadband filters for the g, R, and i bands, and narrow-band filters for Hα 6563 Å(on), and Hα 6630 Å(off), and, more recently, for Hα 6720 Å and Hα 6810 Å. The wide field of the PTF/iPTF Hα images allow us to conduct a program to search for Be star candidates in open clusters of different ages (Yu et al 2015(Yu et al , 2016. In the first of a series (Paper I), we present the cluster sample and their basic properties in Section 2.…”

Section: Introductionmentioning

confidence: 99%

Searching for Be Stars in the Open Clusters with PTF/iPTF. I. Cluster Sample and Be Star Candidates

Lee

et al. 2018

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We conducted a search for Be star candidates in open clusters using Hα imaging photometry of the Palomar Transient Factory Survey to investigate some connections among Be star phenomena, cluster environments, and ages. Stellar members of clusters were identified by spatial distributions, near-infrared magnitudes and colors, and by proper motions. Among 104 open clusters, we identified 96 Be star candidates in 32 clusters; 11 of our candidates have been reported in previous studies. We found that the clusters with age 7.5 < log(t(year))  8.5 tend to have more Be star candidates; there is about a 40% occurrence rate within this age bin. The clusters in this age bin also tend to have a higher Be fraction N(Be)/N(Be+B-type). These results suggest that the environments of young and intermediate clusters are favorable to the formation of Be phenomena. Spatial distribution of Be star candidates with different ages implies that they do not form preferentially in the central regions. Furthermore, we showed that the mid-infrared (MIR) colors of the Be star candidates are similar to known Be stars, which could be caused by free-free emission or bound-free emission. Some Be star candidates might have no circumstellar dust according to their MIR colors. Finally, among 96 Be candidates, we discovered that one Be star candidate FSR 0904-1 exhibits long-term variability on the timescale of ∼2000 days with an amplitude of 0.2-0.3 mag, indicating a long timescale of disk evolution.

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Section: Introductionmentioning

confidence: 99%

Searching for Be Stars in the Open Clusters with PTF/iPTF. I. Cluster Sample and Be Star Candidates

Lee

et al. 2018

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“…Be phenomena are the photometric and spectroscopic variability seen in the main-sequence luminous rapid rotators, known as Be stars, with a luminosity class III−V. In recent years, we have studied the evolutionary effect on the formation of Be stars in open clusters (Yu et al 2015(Yu et al , 2016(Yu et al , 2018 using the Palomar Transient Factory (Law et al 2009) and the intermediate Palomar Transient Factory (iPTF; Kulkarni 2013). The Zwicky Transient Facility (ZTF; Bellm et al 2019;Graham et al 2019;Masci et al 2019) came after iPTF, and its improved data can extend our investigation on the variability of Be stars (Ngeow et al 2019), especially for the Be stars and Be-star candidates at the faint end (m > 13 mag), which were largely excluded from previous works (e.g., in Labadie- Bartz et al 2017).…”

Section: Introductionmentioning

confidence: 99%

HO Puppis: Not a Be Star, but a Newly Confirmed IW And-type Star

Lee

et al. 2021

ApJ

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HO Puppis (HO Pup) was considered as a Be-star candidate based on its γ Cassiopeiae-type light curve, but lacked spectroscopic confirmation. Using distance measured from Gaia Data Release 2 and the spectral-energydistribution fit on broadband photometry, the Be-star nature of HO Pup is ruled out. Furthermore, based on the 28,700 photometric data points collected from various time-domain surveys and dedicated intensive-monitoring observations, the light curves of HO Pup closely resemble those of IW And-type stars (as pointed out by Kimura et al.), exhibiting characteristics such as a quasi-standstill phase, brightening, and dips. The light curve of HO Pup displays various variability timescales, including brightening cycles ranging from 23 to 61 days, variations with periods between 3.9 days and 50 minutes during the quasi-standstill phase, and a semiregular ∼14 day period for the dip events. We have also collected time-series spectra (with various spectral resolutions), in which Balmer emission lines and other spectral lines expected for an IW And-type star were detected (even though some of these lines were also expected to be present for Be stars). We detect Bowen fluorescence near the brightening phase, and that can be used to discriminate between IW And-type stars and Be stars. Finally, despite only observing for four nights, the polarization variation was detected, indicating that HO Pup has significant intrinsic polarization.

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The SED Machine: A Robotic Spectrograph for Fast Transient Classification

Blagorodnova

Neill

Walters

et al. 2018

PASP

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Current time domain facilities are finding several hundreds of transient astronomical events a year. The discovery rate is expected to increase in the future as soon as new surveys such as the Zwicky Transient Facility (ZTF) and the Large Synoptic Sky Survey (LSST) come on line. At the present time, the rate at which transients are classified is approximately one order or magnitude lower than the discovery rate, leading to an increasing "follow-up drought". Existing telescopes with moderate aperture can help address this deficit when equipped with spectrographs optimized for spectral classification. Here, we provide an overview of the design, operations and first results of the Spectral Energy Distribution Machine (SEDM), operating on the Palomar 60-inch telescope (P60). The instrument is optimized for classification and high observing efficiency. It combines a low-resolution (R∼100) integral field unit (IFU) spectrograph with "Rainbow Camera" (RC), a multi-band field acquisition camera which also serves as multi-band (ugri) photometer. The SEDM was commissioned during the operation of the intermediate Palomar Transient Factory (iPTF) and has already proved lived up to its promise. The success of the SEDM demonstrates the value of spectrographs optimized to spectral classification. Introduction of similar spectrographs on existing telescopes will help alleviate the follow-up drought and thereby accelerate the rate of discoveries.

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Be STARS IN THE OPEN CLUSTER NGC 6830

Cited by 4 publications

References 37 publications

Searching for Be Stars in the Open Clusters with PTF/iPTF. I. Cluster Sample and Be Star Candidates

Searching for Be Stars in the Open Clusters with PTF/iPTF. I. Cluster Sample and Be Star Candidates

HO Puppis: Not a Be Star, but a Newly Confirmed IW And-type Star

The SED Machine: A Robotic Spectrograph for Fast Transient Classification

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