A low-dispersion survey spectrograph (LDSS-2) for the William Herschel Telescope

Allington‐Smith, J. R.; Breare, M.; Ellis, Richard S.; Gellatly, Dave; Glazebrook, Karl; Jorden, Paul; Maclean, John; Oates, Paddy; Shaw, Graham; Tanvir, Nial; Taylor, Keith; Taylor, Philip H.; Webster, John R. P.; Worswick, S. P.

doi:10.1086/133471

Cited by 61 publications

(47 citation statements)

References 5 publications

(6 reference statements)

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“…The 25 × 25 region surrounding our bronze sample is shown in Figure 6. All four transients have a faint (25 mag < m i < 22 mag) underlying (Fabricant et al 2005); Blue Channel (Schmidt et al 1989); LDSS3 = Low Dispersion Survey Spectrograph-3 (Allington- Smith et al 1994); GMOS = Gemini Multi-Object Spectrograph (Hook et al 2004).…”

Section: Bronze Samplementioning

confidence: 99%

Rapidly Evolving and Luminous Transients From Pan-Starrs1

Drout

Chornock

Söderberg

et al. 2014

ApJ

319

444

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In the past decade, several rapidly evolving transients have been discovered whose timescales and luminosities are not easily explained by traditional supernovae (SNe) models. The sample size of these objects has remained small due, at least in part, to the challenges of detecting short timescale transients with traditional survey cadences. Here we present the results from a search within the Pan-STARRS1 Medium Deep Survey (PS1-MDS) for rapidly evolving and luminous transients. We identify 10 new transients with a time above half-maximum (t 1/2 ) of less than 12 days and −16.5 > M > −20 mag. This increases the number of known events in this region of SN phase space by roughly a factor of three. The median redshift of the PS1-MDS sample is z = 0.275 and they all exploded in star-forming galaxies. In general, the transients possess faster rise than decline timescale and blue colors at maximum light (g P1 − r P1 −0.2). Best-fit blackbodies reveal photospheric temperatures/radii that expand/cool with time and explosion spectra taken near maximum light are dominated by a blue continuum, consistent with a hot, optically thick, ejecta. We find it difficult to reconcile the short timescale, high peak luminosity (L > 10 43 erg s −1 ), and lack of UV line blanketing observed in many of these transients with an explosion powered mainly by the radioactive decay of 56 Ni. Rather, we find that many are consistent with either (1) cooling envelope emission from the explosion of a star with a low-mass extended envelope that ejected very little (<0.03 M ) radioactive material, or (2) a shock breakout within a dense, optically thick, wind surrounding the progenitor star. After calculating the detection efficiency for objects with rapid timescales in the PS1-MDS we find a volumetric rate of 4800-8000 events yr −1 Gpc −3 (4%-7% of the core-collapse SN rate at z = 0.2).

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Section: Bronze Samplementioning

confidence: 99%

Rapidly Evolving and Luminous Transients From Pan-Starrs1

Drout

Chornock

Söderberg

et al. 2014

ApJ

319

444

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“…We obtained optical imaging observations with the Low Dispersion Survey Spectrograph 3 (LDSS-3, upgraded from LDSS-2 Allington- Smith et al 1994) and the InamoriMagellan Areal Camera and Spectrograph (IMACS; Dressler et al 2006) on the Magellan Clay and Baade 6.5 m telescopes at the Las Campanas Observatory, respectively, in the gri filters spanning from ≈610 days before to ≈1900 days after the optical discovery. In our earliest IMACS I-band image (at Epoch −609), we detect the object with 24.2±0.2 mag (see Figure 1).…”

Section: Ground-based Optical Imagingmentioning

confidence: 99%

The Intermediate Luminosity Optical Transient Sn 2010da: The Progenitor, Eruption, and Aftermath of a Peculiar Supergiant High-Mass X-Ray Binary

Villar

Berger

Chornock

et al. 2016

ApJ

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We present optical spectroscopy, ultraviolet-to-infrared imaging,and X-ray observations of the intermediate luminosity optical transient (ILOT) SN 2010da in NGC 300 (d = 1.86 Mpc) spanning from −6 to +6 years relative to the time of outburst in 2010. Based on the light-curve and multi-epoch spectral energy distributions of SN 2010da, we conclude that the progenitor of SN 2010da is a ≈10-12 M e yellow supergiant possibly transitioning into a blue-loop phase. During outburst, SN 2010da had a peak absolute magnitude of M bol −10.4 mag, dimmer than other ILOTs and supernova impostors. We detect multi-component hydrogen Balmer, Paschen, and Ca II emission lines in our high-resolution spectra, which indicate a dusty and complex circumstellar environment. Since the 2010 eruption, the star has brightened by a factor of ≈5 and remains highly variable in the optical. Furthermore, we detect SN 2010da in archival Swift and Chandra observations as an ultraluminous X-ray source (L X ≈ 6 × 10 39 erg s −1). We additionally attribute He II 4686 Å and coronal Fe emission lines in addition to a steady X-ray luminosity of ≈10 37 erg s −1 to the presence of a compact companion.

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“…Long-slit spectra of the [O iii] nebula in NGC 7252 were obtained with both the Low-Dispersion Survey Spectrograph (LDSS-3; see Allington-Smith et al 1994 for LDSS-2) and the Magellan Echellette (MagE) spectrograph (Marshall et al 2008) at the Clay 6.5 m telescope (see Table 1). All spectra were taken with the spectrograph slits placed at a position angle of P.A.…”

Section: Spectroscopymentioning

confidence: 99%

The [O Iii] Nebula of the Merger Remnant NGC 7252: A Likely Faint Ionization Echo

Schweizer¹,

Seitzer²,

Kelson³

et al. 2013

ApJ

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We present images and spectra of a ∼10 kpc-sized emission-line nebulosity discovered in the prototypical merger remnant NGC 7252 and dubbed the "[O iii] nebula" because of its dominant [O iii] λ5007 line. This nebula seems to yield the first sign of episodic active galactic nucleus (AGN) activity still occurring in the remnant, ∼220 Myr after the coalescence of two gas-rich galaxies. Its location and kinematics suggest it belongs to a stream of tidal-tail gas falling back into the remnant. Its integrated [O iii] λ5007 luminosity is 1.4 × 10 40 erg s −1 , and its spectrum features some high-excitation lines, including He ii λ4686. In diagnostic line-ratio diagrams, the nebula lies in the domain of Seyfert galaxies, suggesting that it is photoionized by a source with a power-law spectrum. Yet, a search for AGN activity in NGC 7252 from X-rays to radio wavelengths yields no detection, with the most stringent upper limit set by X-ray observations. The upper luminosity limit of L 2-10 keV, 0 < 5 × 10 39 erg s −1 estimated for the nucleus is ∼10 3 times lower than the minimum ionizing luminosity of 5 × 10 42 erg s −1 necessary to excite the nebula. This large discrepancy suggests that the nebula is a faint ionization echo excited by a mildly active nucleus that has declined by ∼3 orders of magnitude over the past 20,000-200,000 yr. In many ways this nebula resembles the prototypical "Hanny's Voorwerp" near IC 2497, but its size is 3× smaller and its [O iii] luminosity ∼100× lower. We propose that it be classified as an extended emission-line region (EELR). The [O iii] nebula is then the lowest-luminosity ionization echo and EELR discovered so far, indicative of recent, probably sputtering AGN activity of Seyfert-like intensity in NGC 7252.

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A low-dispersion survey spectrograph (LDSS-2) for the William Herschel Telescope

Cited by 61 publications

References 5 publications

Rapidly Evolving and Luminous Transients From Pan-Starrs1

Rapidly Evolving and Luminous Transients From Pan-Starrs1

The Intermediate Luminosity Optical Transient Sn 2010da: The Progenitor, Eruption, and Aftermath of a Peculiar Supergiant High-Mass X-Ray Binary

The [O Iii] Nebula of the Merger Remnant NGC 7252: A Likely Faint Ionization Echo

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