A Cool and Inflated Progenitor Candidate for the Type Ib Supernova 2019yvr at 2.6 Years Before Explosion

We present Hubble Space Telescope imaging of a pre-explosion counterpart to SN 2019yvr obtained 2.6 years before its explosion as a type Ib supernova (SN Ib). Aligning to a post-explosion Gemini-S/GSAOI image, we demonstrate that there is a single source consistent with being the SN 2019yvr progenitor system, the second SN Ib progenitor candidate after iPTF13bvn. We also analyzed pre-explosion Spitzer/IRAC imaging, but we do not detect any counterparts at the SN location. SN 2019yvr was highly reddened, and comparing its spectra and photometry to those of other, less extinguished SNe Ib we derive $E(B-V)=0.51\substack{+0.27\\-0.16}$ mag for SN 2019yvr. Correcting photometry of the pre-explosion source for dust reddening, we determine that this source is consistent with a $\log(L/L_{\odot}) = 5.3 \pm 0.2$ and $T_{\mathrm{eff}} = 6800\substack{+400\\-200}$ K star. This relatively cool photospheric temperature implies a radius of 320$\substack{+30\\-50} R_{\odot}$, much larger than expectations for SN Ib progenitor stars with trace amounts of hydrogen but in agreement with previously identified SN IIb progenitor systems. The photometry of the system is also consistent with binary star models that undergo common envelope evolution, leading to a primary star hydrogen envelope mass that is mostly depleted but seemingly in conflict with the SN Ib classification of SN 2019yvr. SN 2019yvr had signatures of strong circumstellar interaction in late-time ($>$150 day) spectra and imaging, and so we consider eruptive mass loss and common envelope evolution scenarios that explain the SN Ib spectroscopic class, pre-explosion counterpart, and dense circumstellar material. We also hypothesize that the apparent inflation could be caused by a quasi-photosphere formed in an extended, low-density envelope or circumstellar matter around the primary star.Comment: 22 pages, 9 figures, submitted to MNRA

Evidence for Extended Hydrogen-Poor CSM in the Three-Peaked Light Curve of Stripped Envelope Ib Supernova

We present multi-band ATLAS photometry for SN 2019tsf, a stripped-envelope Type Ib supernova (SESN). The SN shows a triple-peaked light curve and a late (re-)brightening, making it unique among stripped-envelope systems. The re-brightening observations represent the latest photometric measurements of a multi-peaked Type Ib SN to date. As late-time photometry and spectroscopy suggest no hydrogen, the potential circumstellar material (CSM) must be H-poor. Moreover, late (>150 days) spectra show no signs of narrow emission lines, further disfavouring CSM interaction. On the contrary, an extended CSM structure is seen through a follow-up radio campaign with Karl G. Jansky Very Large Array (VLA), indicating a source of bright optically thick radio emission at late times, which is highly unusual among H-poor SESNe. We attribute this phenomenology to an interaction of the supernova ejecta with spherically-asymmetric CSM, potentially disk-like, and we present several models that can potentially explain the origin of this rare Type Ib supernova. The warped disc model paints a novel picture, where the tertiary companion perturbs the progenitors CSM, that can explain the multi-peaked light curves of SNe, and here we apply it to SN 2019tsf. This SN 2019tsf is likely a member of a new sub-class of Type Ib SNe and among the recently discovered class of SNe that undergo mass transfer at the moment of explosionComment: 23 pages, Comments are welcome, Submitted to Ap

SN 2022oqm: A Multi-peaked Calcium-rich Transient from a White Dwarf Binary Progenitor System

We present the photometric and spectroscopic evolution of SN 2022oqm, a nearby multi-peaked hydrogen- and helium-weak calcium-rich transient (CaRT). SN 2022oqm was detected 19.9 kpc from its host galaxy, the face-on spiral galaxy NGC 5875. Extensive spectroscopic coverage reveals a hot (T >= 40,000 K) continuum and carbon features observed ~1 day after discovery, SN Ic-like photospheric-phase spectra, and strong forbidden calcium emission starting 38 days after discovery. SN 2022oqm has a relatively high peak luminosity (MB = -17 mag) for CaRTs, making it an outlier in the population. We determine that three power sources are necessary to explain SN 2022oqm's light curve, with each power source corresponding to a distinct peak in its light curve. The first peak of the light curve is powered by an expanding blackbody with a power law luminosity, consistent with shock cooling by circumstellar material. Subsequent peaks are powered by a double radioactive decay model, consistent with two separate sources of photons diffusing through an optically thick ejecta. From the optical light curve, we derive an ejecta mass and 56Ni mass of ~0.89 solar masses and ~0.09 solar masses, respectively. Detailed spectroscopic modeling reveals ejecta that is dominated by intermediate-mass elements, with signs that Fe-peak elements have been well-mixed. We discuss several physical origins for SN 2022oqm and favor a white dwarf progenitor model. The inferred ejecta mass points to a surprisingly massive white dwarf, challenging models of CaRT progenitors.Comment: 33 pages, 17 figures, 5 tables, Submitted to Ap

SN 2019ehk: A Double-peaked Ca-rich Transient with Luminous X-Ray Emission and Shock-ionized Spectral Features

We present panchromatic observations and modeling of the Calcium-rich supernova (SN) 2019ehk in the star-forming galaxy M100 (d approximate to 16.2 Mpc) starting 10 hr after explosion and continuing for similar to 300 days. SN 2019ehk shows a double-peaked optical light curve peaking at t = 3 and 15 days. The first peak is coincident with luminous, rapidly decaying Swift-XRT-discovered X-ray emission (L-x approximate to 10(41) erg s(-1) at 3 days; L-x proportional to t(-3)), and a Shane/Kast spectral detection of narrow Ha and He II emission lines (nu approximate to 500 km s(-1)) originating from pre-existent circumstellar material (CSM). We attribute this phenomenology to radiation from shock interaction with extended, dense material surrounding the progenitor star at r (0.1-1) x 10(17) cm. The photometric and spectroscopic properties during the second light-curve peak are consistent with those of Ca-rich transients (rise-time of t(r) = 13.4 +/- 0.210 days and a peak B-band magnitude of M-B = -15.1 +/- 0.200 mag). We find that SN 2019ehk synthesized (3.1 +/- 0.11) x 10(-2) M-circle dot of Ni-56 and ejected M-ej = (0.72 +/- 0.040) M-circle dot total with a kinetic energy E-k = (1.8 +/- 0.10) x 10(50) erg. Finally, deep HST pre-explosion imaging at the SN site constrains the parameter space of viable stellar progenitors to massive stars in the lowest mass bin (similar to 10 M-circle dot) in binaries that lost most of their He envelope or white dwarfs (WDs). The explosion and environment properties of SN 2019ehk further restrict the potential WD progenitor systems to low-mass hybrid HeCO WD+CO WD binaries

The Young Supernova Experiment Data Release 1 (YSE DR1) Light Curves

This is the official Zenodo data release of the Young Supernova Experiment Public Data Release 1 (YSE DR1) light curves associated with the paper, &quot;The Young Supernova Experiment Data Release 1 (YSE DR1): Light Curves and Photometric Classification of 1975 Supernovae&quot;. YSE DR1 is comprised of processed multi-color Pan-STARRS1 (PS1)-griz and Zwicky Transient Facility (ZTF)-gr photometry lightcurve files in the SNANA data format of 1975 transients with host galaxy associations, redshifts, spectroscopic/photometric classifications, and additional data products from November 24th, 2019 to December 20, 2021. See Aleo et al. (2022) for details. &quot;yse_dr1_zenodo.tar.gz&quot; -- All lightcurve data with no cut on signal to noise (S/N). &quot;yse_dr1_zenodo_snr_geq_4.tar.gz&quot; -- All lightcurve data with S/N &amp;gt;= 4. This can be used to recreate the analysis in Aleo et al. (2022). &quot;parsnip_results_for_ysedr1_table_A1_full_for_online&quot; -- The full version of Table~C2 in Aleo et al. (2022). The full ParSNIP (tertiary classification) results for YSE DR1. NOTE: An example tutorial on how to download the YSE DR1 data (full sample, spec sample, phot sample), grab metadata, and recreate a plot from the paper can be found on Github.</span